protection
automation
and control
magazine
Spring 2008
The Guru:
Shri Mata Prasad
page 60
$7 US
18 POWER SYSTEMS ANALYSIS
38 DOUBLE ENDED FAULT LOCATOR
46 IEC 61850 ENGINEERING
54 EMTP MODELING
Spring 2008
www.
.org
3
contents
PROTECTION, AUTOMATION & CONTROL WORLD SPRING 2008/VOLUME 04
10
4 editorial
38
10 letters
77
91
11 news
The latest news from the world of electric
power systems protection, automation
and control
53 legal issue
18 cover story
Class action lawsuits - are they possible after
a blackout occurs?
On the challenges faced by protection engineers today and how to overcome them
54 EMPT modeling
27 IEC 61850 update
The application of electromagnetic transient programs (EMPT) for power system
protection
The life cycle of an IEC standard and how it
relates to IEC 61850
28 lessons learned
94
11
18
60
Substation "horror stories" - manufacturer's
analysis and perspective on some events
Shri Mata Prasad shares with us the story
of his life and his thoughts about our
industry
34 blackout watch
70 history
Review of recent blackouts or disturbances
around the world
This is the second article on the developments of distance protection
36 utilities challenges
77 I think
Challenges and opportunities faced by the
utilities when using modern protection and
control systems
Do we really need Smart Grids? Marco Janssen shares his thoughts on that issue
38 fault locator
Precise distance to fault locator with twoend phasor measurement transmitted via
serial protection data interface
83
70
60 the guru: interview
46 61850 engineering
Review on designing IEC 61850 systems for
maintenance, retrofit and extension
79 industry reports
CIGRE B5 goals and activities, as well as an
IEEE PSRC guide on breaker failure protection are discussed
83 conference reports
Reports on conferences in the United
Kingdom and the United States
91 photos of the issue
A selection of photos submitted by PAC
World readers is presented
93 book review
PAC World Photo Gallery
presents Protection
in Digital Art
94 hobby
Benton Vandiver III shares with us some of
his BBQ experience and secrets
98 final thoughts
98 events calendar
Go to pages 8 and 68
COVER PAGE: SUBSTATION DETECTIVE, ILLUSTRATION BY Terry McCoy
PAC.SPRING.2008
by Alex Apostolov
Comment
from the editor
4
PAC World
is your forum
In this issue we continue our discussion of
topics important to protection professionals.
After discussing the concepts for protection of
transmission lines around the world, now we are
going to talk about electric power systems analysis
from the point of view of protection.
The work of a protection specialist
in many ways is similar to what a
detective needs to do. It actually goes
beyond that, because while Sherlock
Holmes needs just his magnifying
glass and pipe to solve a crime that
has already occurred, we need a
very different set of tools not only to
solve a system event after it happens,
but also to design and configure the
protection, automation and control
system in a way that will prevent
such an event.
Like detectives we first need to
collect the evidence. This requires
a trained eye that can recognize
something significant that may look
like garbage to everybody else. But a
trained eye is not sufficient. Powerful
tools can definitely help us to figure
out not only what happened, but
also when and where. If we keep the
detective analogy in mind, this is like
asking today’s investigators to use
only a magnifying glass instead of
DNA testing, microscopes, spectral
analysis and other available tools.
Understanding when an event
occurred is another important task
in our detective work. Modern
protection IEDs provide time
stamping of different events
based on relatively accurate time
synchronization. However, we
usually do not think about when
the time-stamp was actually put on
the event. For example, if the device
senses the change of state of a breaker
based on monitoring of its binary
inputs, the enabling of filtering and
PAC.SPRING.2008
the frequency of checking of the
inputs may have a significant impact
on the accuracy of the time stamp.
Fault locators are another
very powerful tool that helps us
answer the question of where a
fault occurred. Here again we need
to understand the limitations
of single-ended fault location
algorithms and the benefits of
double-ended methods. The
impact of mutual coupling and
unbalanced configurations should
be considered.
The task to prevent some
system events from happening
can also be achieved by using the
twenty first century technology
available to us. We already made the
transition from electromechanical
relays to microprocessor based
mult ifunc t ional protec t ion,
automation and control intelligent
electronic devices. However,
even though we have advanced
programs for fault analysis and
protection coordination, they are
predominantly based on sequence
components for modeling the
generators, transformers and power
lines. They were used for calculation
of fault currents and voltages when
the main tool available to us was a
slide-rule.
The problem is that sequence
components work well for a
balanced system. But in real life most
transmission lines are untransposed,
with unsymmetrical configuration
and running in parallel with other
lines with the same or different
voltage. Modeling such systems
with symmetrical components
introduces errors that may lead to
relay misoperation followed by local
or wide area disturbance.
It is important to also understand
that the model usually used is based
on the sub-transient impedance of
the generators. We know that this
model is valid only during the first
few cycles after a fault occurs in the
system. So we need to be aware of
what impact this may have on the
coordination of protection elements
that have longer time delays.
Modeling of the protection
relay characteristics as generic
mho or quadrilateral introduces
another level of uncertainty in the
performance of a protection device
under real system conditions.
The use of electromagnetic
transient programs can
significantly improve the accuracy
of the analysis of possible fault
condit ions in systems w ith
different configurations. Accurate
modeling not only of the distance
characteristic, but also all other
components of the dist ance
protection function can bring the
coordination and relay setting
process to a different level.
I hope that the articles in this
issue are going to trigger some
reaction from you and start a process
of change that will allow us to better
design, configure and operate
protection systems. It is clear that we
can change the way we do things. As
Leo Tolstoy said:
Everyone thinks of changing
the world, but no one thinks
of changing himself.
Job track - Experience - Hobby
contributors
6
Demetrios Tziouvaras
Demetrios Tziouvaras was born in Monahiti, Grevena, Greece. He holds a M. Sc. in Electrical
Engineering from Santa Clara University, CA, USA. He worked for 8 years with Pacific Gas
and Electric Co and joined the R&D Engineering Department of Schweitzer Engineering
Laboratories, Inc. in 1998. Mr. Tziouvaras is a senior IEEE member and member of the PSR
Committee. He is a member of CIGRE and the convenor of CIGRE SC B5.15 on “Modern
Distance Protection Functions and Applications.” He has taught many seminars and is the
author of more than 35 conference papers, and three patents. He served as chairman of an
IEEE PSRC working group that developed an IEEE PES tutorial on “EMTP Applications to
Power System Protection”. When he has free time on weekends he likes to cook some of his
favorite Greek dishes, take care of the Tziouvara’s ranch near San Francisco, CA, go camping
and ride his two beautiful horses with his wife Diana. Mr. Tziouvaras is married and
has a daughter and a son named Panagiota and Athanasios respectively.
Marco C. Janssen
Marco C. Janssen graduated the Polytechnic in Arnhem, The Netherlands and further
developed his professional skills through programs and training courses.
He is President and Chief Commercial Officer of UTInnovation LLC – a company that
provides consulting and training services in the areas of protection, control, substation
automation and data acquisition, and support on the new international standard IEC
61850, advanced metering and power quality. He is a member of WG 10, 17, 18, and 19
of IEC TC57, the IEEE-PES and the UCA International Users Group.
Marco coaches his son’s football team and enjoys watching
science fiction movies as well as traveling, good food and wine.
Ivan De Mesmaeker
Ivan De Mesmaeker received M.Sc. Engineering Degree from the University of Brussels in
1968. He joined BBC (later ABB) in Baden, Switzerland in 1969. He was Project leader of
the first steady-state distance protection of BBC and of the first numerical line protection,
as well as test set equipment. He is currently Senior Technical Manager for Protection and
Control Systems. He was member of CIGRE Working Group 34-04 (1980-1986) and
Swiss delegate in SC34 of CIGRE (till August 2000). He received the CIGRE Technical
Committee Award in January 2001 and has been Chairman of Study Committee B5 of
CIGRE since 2002. He has authored and co-authored several professional papers.
When not working, he enjoys skiing, hiking, camping and
editing of video films about holidays.
Wolfgang Wimmer
Wolfgang Wimmer works for ABB Switzerland in Baden. He is Principle Engineer in the
development of substation automation systems. He has a M. Sc. degree as well as a Ph.D. in
Computer Science from the University of Hamburg. After some years developing Computer
networks at the German Electron Synchroton DESY in Hamburg he changed to ABB for
development of train control systems, later Network Control Systems.
He has more than 20 years experience with development of substation automation systems.
He is a member of IEC TC57 WG 19 and WG 10, and editor of IEC 61850-6.
Wolfgang likes walking in the mountains as well as at rivers, reading popular books about
biology, especially neuroscience, as well as science fiction and fantasy books.
He also enjoys listening to country music.
PAC.SPRING.2008
All is Well
continued on page 68
GALLERY
Photography
Digital
Art byby
Harmeet
Terry McCoy,
Kang
HawkEye Communications,
Houston,
Texas.
Locus
of a swing
passing
harmlessly by a
moon-shaped like
distance characteristic
(load blinders cut out)
Harmeet Kang
UK
Harmeet is a
protection design engineer
at AREVA T&D
Automation, Stafford, UK
who believes that
protection is not just
science, but
art as well
PAC.SPRING.2008
PAC.SPRING.2008
10
letters
Don't hesitate.
Tell us what you like
and what we can
what you think
d o b e tt e r . S h a r e
your thoughts and
experiences.
One Sunday morning I was surprised at
the book my son Thomas had chosen to
pick up while I was cleaning. I admit the
book fell over and I had to stand it back
the way he originally had it before I turned
on the camera, but the pose is identical to
his natural interest a few seconds before­
hand and he still seems intrigued. Maybe
there is hope for the industry - unless I tell
him that law or finance pays more!
protection. Make him feel that it is COOL
and let us know if it is working, so we can
use your experience.
Simon Richards, UK
Luis Antonio Soto R., Mexico
PAC World: Dear Simon, yes, there is
hope. Please keep your son excited about
PAC World: Dear Luis Antonio , we plan
to have an issue next year dedicated to
testing. However, we would like to encou­
rage our readers to share their knowledge
of the subjects mentioned in Luis’ e-mail.
I would like to see a section on Tips and
Tricks: how to test faster, how to do some­
thing easier, suggestions by vendors, etc.
Also a section on how to quickly calculate
settings in the field for commissioning
would be useful.
pending on the fault, the current could be
higher than the interrupting rating so they
are blocked from operating in these cases.
This adds some complexity/sensitivity to
the relay coordination because the line
relays must see these faults and operate
quickly.
Thanks for the wonderful magazine. Fi­
nally, a magazine that I feel like carrying
with me wherever I go. Keep up the good
work!
Amitava Maity
In the article "A Pilot Protection system
Failure - An Investigation," Mr. Collin M.
Martin mentioned the term "FID rating" on
page 29 of the Winter 2008 issue. I've ne­
ver heard this term. What does it mean?
I found your magazine/web site very
interesting and useful. In order to inform
other specialists about it, an e-mail was
sent to hundreds of people who are active
in the Protection, Automation and
Control world. Your activities are very valu­
able and I want to thank everybody who
supports this idea.
João Ricardo da Mata Soares de Souza, Brazil
Mehdi Gerivani, Iran
PAC World: Dear Ricardo, the following is
the response we received from the author
of the article:
FID = Fault Interrupting Device. In this in­
stance FID is referring to circuit switchers
that are only rated to interrupt 20kA. De­
PAC World: Dear Mehdi , thank you for
spreading the word about PAC World.
Please also encourage your colleagues to
share their experiences through articles,
comments, photos and anything else they
think would be of interest.
pac world
address
Editor in chief: dr. Alexander Apostolov (USA)
Advisory Board: dr. Damir Novosel (USA),
PAC World (Email: editor@pacw.org)
Managing Editor: Izabela Bochenek (Poland)
prof. Peter Crossley (UK), prof. Paul Lee (Korea),
8 Greenway Plaza, Suite 1510
Editors: Clare Duffy (Ireland), Caroline Fricks-Wood
prof. Xinzhou Dong (China),
Houston, TX 77046, USA
Christoph Brunner (Switzerland)
prof. Mohindar Sachdev (Canada),
The PAC World magazine is published quarterly by PAC World. All rights
Design Layout: Marek Knap (Poland)
Jorge Miguel Ordacgi Filho (Brazil),
reserved. Reproduction in whole or in part of any material in this publication
Graphic Design: Terry McCoy (USA),
Rodney Hughes (Australia),
is allowed.
Iagoda Lazarova (USA), Dan-Andrei Serban (Romania)
Graeme Topham (South Africa)
Parent company: OMICRON electronics Corp. USA
PAC.SPRING.2008
industry
+tech
news
11
1
Franklin
Institute
Award
V i r g i n i a Te c h e n g i n e e r i n g
professors James Thorp and Arun
Phadke are recipients of the
2008 Benjamin Franklin Medal in
Electrical Engineering for their
combined contributions of more
than 60 years to the power
industry.
Specifically, they have collaborated
on many advances that strengthen
the electric utility industry’s ability
to prevent power grid blackouts,
or to make them less intense and
easier to recover from.
For this collaborative work, the
Franklin Institute has now included
Thorp and Phadke into its list of
the greatest men and women
of science, engineering, and
technology.
Competition for the Benjamin
Franklin Medals is international.
Participants from seven fields of
science are eligible: chemistry,
computer and cognitive science,
earth and environmental science,
electrical engineering, life
science, mechanical engineering
and physics. In the past, Albert
Einstein, Thomas Edison, Orville
Wright, Marie and Pierre Curie and
Jane Goodall have been among the
recipients.
“Professors Thorp and Phadke, both
members of the National Academy
of Engineering, are considered
to be preeminent trailblazers in
their fields of electric power,” said
Richard Benson, dean of Virginia
Tech’s College of Engineering.
“Their research has a direct impact
on the daily lives of everyone
around the world. In fact, both
are also members of a prestigious
Chinese funded research team
directed to improve the protection
and security of the worldwide,
interconnected electric power
grid.”
For more information go to: http://
www.fi.edu/franklinawards/
PAC.SPRING.2008
Virginia Tech
engineering
professors James
Thorp and Arun
Phadke , USA
you can't miss it
industry news
12
2
Toshiba’s
State-of-the-Art Line
Differential Relay –
Now with IEC 61850
Toshiba continues the roll-out of
its IEC 61850 product range, with its
world-beating current differential
protection GRL100 now supporting
the global standard for substation
communications. GRL100 follows the
GRZ100 distance protection, GRT100
transformer protection and GBU100
bay controller, all of which have been
certified IEC 61850 compliant by KEMA.
Toshiba’s GRL100 is an advanced line
differential protection relay which
combines sub-cycle performance with
a range of enhancements such as
integrated distance protection, GPS
synchronisation
with sophisticated
back-up modes,
multi-phase
reclosing for
double-circuit lines
and IEC 61850
capabilities.
4
3
2007 Karapetoff
Award
Outstanding Technical Achievement
The 2007 Vladimir
Karapetoff Award
was given to
Stanley H. Horowitz,
Consultant and
Arun G. Phadke of
Virginia Tech on
March 19, 2008
at Hyatt Regency
at Penn’s Landing,
Philadelphia, PA.
The award is given
for their technical
contributions to the
field of power system
protection and
control.
This major HKN
recognition for career
accomplish­­ment in
the field of electrical
and computer
engineering dates
from 1922, when the
Board of Governors
established the
award in honor of
Vladimir Karapetoff,
an IEEE Fellow and a
prominent member of
Eta Kappa Nu.
The award is given
annually to an
electrical practitioner
who is distinguished
himself/herself
through an invention, Stanley H. Horowitz
a development, or a
discovery in the field of of the invention,
electro technology.
develop­ment, or
Factors that are
discovery; its impact
considered in
on the public welfare
bestowing the
and standard of living,
award include the
and/or global stability;
impact and the
and the effective
scope of applicability lifetime of its impact.
GE Digital Energy's
breakthrough in networking
GE Digital Energy unveils a breakthrough in networking
hardware that can reduce up to 70% of your total communications
costs with the introduction of their new Multilin UR Switch
Module. A fully managed, embedded Ethernet switch for their
flagship Universal Relay (UR), this advanced, 6-port Ethernet
Switch eliminates the need for external, rack-mounted switches.
More importantly, it significantly reduces the total costs
associated with hardware, installation, wiring, and troubleshooting
required for today’s traditional substation communication
architectures. The Multilin UR Switch Module delivers full station
management, monitoring, and control functionality with complete
communications redundancy.
PAC.SPRING.2008
13
6
New Configuration
and Monitoring Tool
IEC 61850
5
SIPROTEC
Fast Bus Transfer scheme solution
Applications of Siemens SIPROTEC
Relays have revolutionized the
transfer scheme designs. Using only
two basic feeder protection relays
Siemens can realize for example a
Fast Motor Bus Transfer Scheme
per ANSI C50.41-2000. Motor Bus
systems are critical loads which can
not endure long separations from
the power supply. In both industrial
and utility power plant applications,
the consequences of an unplanned
motor bus outage can be costly,
time consuming and dangerous.
The load must be transferred to
a redundant source. The speed
7
of this transfer is critical for the
stress of the electrical system, the
continuity of plant operations and
the protection of the motors. The
High-Speed Motor Bus Transfer
Scheme is capable of providing
both close and open transition
transfers. Transfer schemes are
realized for most applications
per customer specifications. The
whole system is delivered fully
programmed, tested and ready for
installation. Optionally incorporating
IEC61850 communications makes
implementation fast, secure and
cost-effective.
AREVA T&D Automation launched
MiCOM S1 Studio – a new integrated
IED configuration and monitoring tool
that will make users’ life easier by
providing an intuitive and versatile
interface with built-in file management
facilities and IEC 61850 support.
The MiCOM S1 Studio interface
was designed with simplicity and
customization in mind. It has a
panel-based interface where elements
are resizable, dockable, movable and
removable. The software remembers
your layout when you exit, so that
the next time when you use it, you
start where you finished. MiCOM
S1 Studio has been developed with
the various needs of different users
in mind - protection
a n d c o m m i ss i o n i n g
engineers or system
integrator, who want to
configure devices offline
in the office or work
online communicating
directly with devices in
the substation.
IEC 61850 Tool
A new version of the IED Scout !
OMICRON electronics released
a new version of the IED Scout - an
IEC 61850 tool that can be used
both in the laboratory or in the
field for testing, troubleshooting,
commissioning and IED
development.
IED Scout allows the user to perform
different tasks, such as :
extract the data model from an
IED
check the extracted IED data
model
create an SCL file
subscribe and monitor GOOSE
messages
poll data
receive reports
In addition to the existing
capabilities, the new version
supports:
GOOSE Sniffer (capturing GOOSE
messages online on the network)
Drag & Drop / Copy & Paste of
discovered GOOSE information to
the GOOSE Configuration Module
Improved user interface
A free demo version with some
restricted functionality is available
at:
http://www.omicron.at/en/
products/substation/iec-61850/
iedscout/
PAC.SPRING.2008
you can't miss it
industry news
14
8
Non-Operational
Data Access
Enterprise
Accessing breaker wear, fault records and
oscillography from relays is now easier through
the use of a set of software tools for the Orion
Automation Platform. NovaTech's Orion Software
Suite includes tools to:
Access relays remotely, through Orion
Make Breaker Wear, History and Short Event
Summaries available to SCADA
Automatically retrieve, parse and disseminate
Full-Length Event Report to enterprise PCs
Display relay data on pre-formatted web pages
served from Orion.
Traditional automation function, such as
accessing SCADA data, retrieving time stamps
and sending down IRIG-B, are also supported in
the Software Suite.
For more information, please visit our site.
9
Substation
Terminal Block and Switch
– All In One
SecuControl, Inc.
is known for their
testblock / testplug
system ITS.
Now, the company
from Alexandria,
VA o f f e r s a n e w
terminal block with an
integrated test access
point called Secu
Access.
Secu Access (SAX)
is built for relay testing,
meter testing and CT
current measurement.
It can be mounted on
PAC.SPRING.2008
DIN-rail or with screws,
making it exceptionally
versatile.
Secu Access
performs both
functions of a terminal
block and switch, and
therefore reduces
wiring and panel space
needs.
The terminal block/
switch has a modular
buildup and attaches
to many wire terminal
types (ring/spade/solid
wire). Testing is easily
done by inserting
a testplug into the
access point. Just like
the Interface Test
System, SAX features
a finger-safe front and
keyed entry system.
Current shorting
t e s t p l u g s p r ov i d e
additional user safety.
With an internal
resistance of only ca.
2mΩ, SAX is an ideal
solution for the use
with highly sensitive
microprocessor relays.
15
1
280 MW Sun Power Plant in
Arizona, USA
The Spanish company Abengoa Solar, one
of the leaders in developing and building large
solar plants, has signed a contract with Arizona
Public Service Co. (APS) – the largest energy utility
in the state of Arizona (USA), to build a 280 MW
solar power plant, scheduled to go into operation
by 2011.
The solar plant will be located about 100 km
west of Phoenix, near Gila Bend, Arizona. It has
been named Solana, meaning “a sunny place”
in Spanish. The plant will employ a proprietary
Concentrating Solar Power (CSP) trough
technology developed by Abengoa Solar. It will
cover a surface of around 1,900 acres.
The solar trough technology uses trackers with
high precision parabolic mirrors that follow the
sun’s path and concentrate its energy, heating a
fluid to over 700 degrees Fahrenheit and using that
heat to turn steam turbines. The solar plant will
also include a thermal energy storage system that
allows for electricity to be produced as required,
If only 2%
of the solar
from East
Steam at 100 bar
and 390 o C
to West
Sunpath
Parabolic
mirror
radiation from
the world’s
even after the sun has set.
The operational scheme is similar to that of
Solnova 1 (Spain), with the addition of storage
capacity as shown in the diagram below.
Parabolic trough systems use an absorber tube as
the collector. Solar radiation is reflected from the
parabolic trough to the focal point of the parabola.
The absorber tube is located at the focal point
and it transfers the solar radiation energy to the
working fluid. This energy is then used to run a
conventional power cycle.
A large benefit of parabolic trough systems
compared to other solar technologies is its
maturity as a technology for being installed at a
commercial level. The first trough plants were
installed in the US in the 1980’s and have since
undergone vast improvement both in cost and
efficiency.
For more information on Abengoa Solar’s solar
trough technology, please visit their website at:
www.abengoasolar.com
Heat collecting
element
technology plant
Steam
turbine
G
Oil
at 395 o C
Direct normal
radiation
Solar through
Recalentador
Superheater
deserts were
used it would
Drive
motor
Condensator
Boiler
Condensator
be enough to
Oil
at 302 o C
supply the
world's power
demands.
Sun tracking principle
Preheater
Power plant scheme
The benefit of
Air picture of CSP
this technology
is that it is a
conventional
thermal power
plant with a solar
energy source.
PAC.SPRING.2008
consider future applications
technology news
16
The "KIZUNA" is a
2
Japan Launches
High-speed Communications Satellite
Mitsubishi Heavy
Industries, Ltd. and the
Japan Aerospace Exploration
Agency (JAXA) launched the
super high-speed Internet
satellite "KIZUNA" (WINDS)
by the H-IIA Launch Vehicle
No. 14 (H-IIA F14) at 5:55 p.m.
on February 23, 2008 (Japan
Standard Time, JST) from the
Tanegashima Space Center.
The launch vehicle flew
smoothly and, at about 28
minutes and 3 seconds after
liftoff, the separation of the
KIZUNA was confirmed.
We would like to express our
profound appreciation for
the cooperation and support
of all related personnel and
organizations that helped
contribute to the successful
launch of the KIZUNA aboard
the H-IIA F14.
At the time of the launch, the
weather was cloudy, wind
speed was 15.2 m/second
from the northeast and the
temperature was 9.7 degrees
Celsius.
The "KIZUNA" is a
communications satellite that
enables super high-speed
data communications of up to
1.2 Gbps to develop a society
without any information
availability disparity, in which
everybody can equally enjoy
high-speed communications
wherever they live.
Using an antenna for South
East Asian countries, we
are aiming to achieve super
high-speed communications
with nations in the Asia/
Pacific region with which
Japan has close ties.
Large-volume and high-speed
communications provided
by the KIZUNA (WINDS) are
expected to be useful in
various areas. For example,
we will be able to contribute
to "remote medicine" that
enables everybody to receive
sophisticated medical
treatment regardless of time
and location by transmitting
Artist Interpretation of GPS satelite
communications
satellite that
enables super
high-speed data
communications
Ka-band Multi-based Antenna
for Southeast Asia
Solar Array Paddle
(Sout Side)
Ka-band Multi-based Antenna
for Japan and vicinity
of up to 1.2 Gbps
Solar Array Paddle
(North Side)
Ka-band Active Phased Array
Antenna (APAA)
clear images of the
conditions of a patient
to a doctor in an
urban area from a
remote area or island
where few doctors are
available. In academic
and educational fields,
schools and researchers
in remote areas can
exchange information
easily. To help cope with
With a larger
antenna of about
5 meters in
diameter, super
high-speed data
communications
of up to 1.2 Gbps
will be available.
(Such a service is
mainly for
organizations and
companies.)
All Composite Images: courtesy of JAXA
disasters, information can
be swiftly provided through
space.
The Internet is now an
integral part of our lives; but
its infrastructure levels vary.
In general, urban
areas with a
large population
have a better
Internet
environment,
whereas
some
mountainous
regions
and remote
islands are not
well-equipped
with Internet
infrastructure due to
its costs.
The KIZUNA (WINDS)
does not require costly
ground equipment. If you
install a small antenna (about
45 cm in diameter) at your
house, you can receive data
at up to 155 Mbps and
transmit data at up to 6 Mbps.
Therefore, even in some areas
where major ground
infrastructure for the Internet
is difficult to establish, people
can enjoy the same level of
Artist's View:
KIZUNA (WINDS)
mission logo.
Internet service as that in
urban areas.
See: http://www.jaxa.jp/countdown/f14/index_e.html.
PAC.SPRING.2008
17
3
Mind Control
of Computers
Emotiv Systems, the pioneer in brain
computer interface technology, has revealed the
Emotiv EPOC™, a neuroheadset that allows
players to control game play with their thoughts,
expressions and emotions. The Emotiv EPOC is
the first high-fidelity brain computer interface
(BCI) device for the video gaming market and will
be available to consumers via Emotiv's web site
and through selected retailers in late 2008.
The neuroheadset is a lightweight, sleek and
easy-to-use wireless device, featuring sensors
that detect conscious thoughts, expressions and
non-conscious emotions based on electrical
signals around the brain. Emotiv's technology
processes these signals, enabling players to control
their in-game character's expressions or actions
and influence game play using their thoughts,
expressions and emotions.
“Being able to control a computer with your
mind is the ultimate quest of human-machine
interaction,” said Nam Do, CEO of Emotiv
Systems. “When integrated into games, virtual
worlds and other simulated environments, this
technology will have a profound impact on the
user's experience.”
The Emotiv EPOC detects over 30 different
expressions, emotions and actions. As a result
of these detections, players will enjoy a more
immersive, lifelike experience. Games will be
able to respond dynamically to player emotions,
enabling, for example, more sophisticated
dynamic difficulty adjustment. Players can
more easily simulate the aspects of gaming by
controlling certain actions and expressions and
manipulating objects in the game using their
brains instead of a keyboard or controller.
In addition to these detections, the Emotiv
EPOC incorporates a gyroscope, which enables
the camera or cursor to be controlled by head
motions. Emotiv and IBM announced that they
intend to explore the potential of Emotiv's BCI
The neuroheadset is a light­
weight, sleek and easy-to-use
wireless device.
Human thoughts,
expressions and
emotions are
captured by the
neuroheadset.
To share your
ideas about what
we can do with
"mind control of
computers",
please send an
e-mail to:
editor@pacw.org
technology beyond the gaming market, into
more strategic enterprise business markets
and virtual worlds. IBM and Emotiv plan to
explore how to make these environments more
personal, intuitive, immersive and ultimately
more lifelike. IBM also intends to explore how
the Emotiv headset may be used for researching
other possible applications of Emotiv's BCI
technology, including virtual training and
learning, collaboration, development, design and
sophisticated simulation platforms for industries
such as enterprise and government.
“The use of BCI technology represents a potential
breakthrough in human-machine interfaces,
changing the realm of possibilities not only for
games, but in the way that humans and computers
interact,” said Paul Ledak, vice president, IBM
Digital Convergence. “As interactions in virtual
environments become more complex, mice and
keyboards alone may soon be inadequate. BCI is an
important component of the 3D Internet and the
future of virtual communication.”
The brain is made up of approximately 100
billion nerve cells, which are called neurons.
When these neurons interact, an electrical
impulse is emitted, which can be observed using
non-invasive electroencephalography (EEG).
PAC.SPRING.2008
Brain computer
interface
technology
works by
observing an
individual's
electrical brain
activity and
processing
it so that
computers can
take inputs
from the
human brain.
by Paul F. McGuire, Ashok Gopalakrishnan,Electrocon International, Inc.,
Anthony T. Giuliante, ATG Consulting Inc.,
Power Systems Analysis
cover story
20
Paul McGuire
joined Electrocon
after receiving his
MSc (EE) and EE
Professional degree
from The University
of Michigan in 1974.
He has participated
in every phase
of the work of
Electrocon, and is
currently involved
in software project
management and
licensing, managing
and recruiting staff,
customer relations
and customer technical training.
A registered professional engineer in
the State of Michigan since 1984, Paul
is a member of IEEE,
CIGRE, Tau Beta Pi
engineering honor
society, Sigma Pi
Sigma physics honor
society, and
Phi Kappa Phi.
Downsizing is already a fact.
New technologies must be
provided to the remaining
engineers.
Our views are shaped by our direct experience
in the field, which for some of us goes back almost as far
as Dylan’s lyrics! Electrocon started developing tools for
computer-aided protection engineering in 1985, working
with an advisory committee of working protection engineers
from ten leading North American power utilities. The goal
then was a combined network and protection system model
to support automated relay setting and coordination checking.
Underlying the model would be a true database management
system to manage the massive data. Today, network models
of 2,000 to 10,000 buses with protection system models of
5,000 to 50,000 relays are common. A master library of over
5,500 manufacturer-specific relay styles supports model
development, and more relays are requested and developed
all the time. (Figure 3)
The advisory committee's wisdom has become more
apparent and their objectives even more relevant now, when
we look at the challenges our protection community is facing
twenty-five years later. We'll look at a few of the problems
faced by our ever-changing electric power industry, and will
propose solutions from our unique perspective as software
developers and consultants who have worked with protection
groups around the world.
Key issues
Organizational isolation. This one might surprise you,
in this age of communication, but organizational isolation
is an increasingly important problem. Most utilities are
interconnected with their neighbors and are interdependent
with them by virtue of the energy they buy, sell, or transport,
but evidence of isolation is everywhere you look. Planning,
protection, and operations are separate departments within
companies. Generation, transmission, and distribution
functions are all served by different entities. Business people
have business goals and ask questions like, “How can we
make the company more profitable?" and "How can we do
our work with a smaller, more efficient staff?” Engineers
have engineering goals and ask questions like, “How can we
provide energy more reliably?" and "How can we design our
systems the right way?”
A very important effect of organizational isolation is
the failure, reluctance, or inability to share data among the
stakeholders who could do a better job if they had access
to it. Within a given company, for example, planning,
protection, and operations are separately modeling the same
network. Historically, this came about because the different
objectives of each group required different models of the same
equipment. Whatever the reasons, the need now is for real
cooperation among these groups. For example, few protection
engineers have access to power flow data that would enable
them to routinely account for load current extremes in their
1 Proportion of miscoordinated conditions, 2 Protection functions requiring
before and after Wide-Area Review
recalculation
Before
After
Coordinated operation
Transmission
miscoordination
PAC.SPRING.2008
Distribution or general
miscoordination
Miscoordination
cannot be solved
50 50N Recalculated
Z1 Recalculated
51 51N Recalculated
Z2 Recalculated
k0 Recalculated
67N Recalculated
21
fault calculations, which would give them better settings.
Planners run electromechanical transient stability simulations
without the benefit of a realistic model of the protection
system, which would give more reliable warnings that the
actions of protective devices may affect the scenarios being
studied. Operations personnel would benefit from a timely
warning if credible contingencies will overload lines to the
extent of risking protective device operation. Likewise, why
shouldn't SCADA systems warn the protection group about
relay loading and CT rating infractions?
Companies experience parallel data sharing failures,
as well. For many companies, the biggest shortcoming in
the protection group’s network model is the absence of an
up-to-date model of their neighbors’ systems. National
security issues and competitive concerns play a role, but in
many cases there are simply not enough people around to
do the necessary communicating. Some utilities' security
rules prevent vendors from examining and trouble-shooting
their data, requiring the vendor instead to use guesswork
and trial-and-error to find the cause of reported problems.
And in a recent case, a company experienced measurable
delays in restoring power after a blackout, because they were
not allowed to know what generation was available to their
system - this in the name of fair competition!
Experience Base. A second area of change and challenge
for our profession is the diminishing experience base. We
see several reasons for this. Utility reorganization (read
downsizing) has been underway around the world since the
early 1990’s and has never led to increases in engineering
3 R-X display of ABB, Siemens and SEL
relays
staffs. Retirements among engineers in the baby boomer
generation in North America and Europe is another
well-recognized cause. These losses combine with the
diminished appeal to younger generations of careers in power
engineering, particularly in countries with an affluent middle
class and higher-paid alternatives.
Inadequate staffing contributes to another quality issue: in
a surprising number of utilities the adequacy of the network
model is marginal and the protection system model is absent
or nearly so. We often see incorrect or incomplete transformer
models, mutual couplings with reversed signs, and, on
occasion, the absence of zero-sequence branch data.
Prot ec t ion en gineer s are le ar nin g more by
on-the-job-training and starting out with less depth of
underlying theory and concepts. And that's even more of a
problem because fewer protection groups today have resident
experts or “gurus” to call on. Then, if engineers call the relay
manufacturers, they find the vendors themselves have lost
expertise in their old electromechanical relay products, many
of which are still in service, although their builders are long
gone.
Apar t from these phenomena , there is the
thought-provoking observation made to us by the late Dr.
Mark Enns, an IEEE Fellow and founder of Electrocon, at the
end of his career: “You just don’t see the towering intellects
anymore who used to dominate our technical meetings.”
We would like to think that this is more a reflection of the
stage of development of power system theory and solution
methods than the numbers and mental prowess of the present
generation of engineers.
Imposed Solutions. A third component of change
and challenge is the effect of government-imposed
requirements and solutions. The issue of energy demand
vs. the environment is properly one for the public arena,
but that arena can only be expected to yield more restrictive
government regulations. The present light precipitation
may well become a blizzard. Barring a long prayed-for
breakthrough in fusion power, our civilization has two sources
of new baseload energy: coal and nuclear. A heavy focus will
remain on alternative energy sources and conservation, as the
environmental debate heats up (pun intended). This situation
can only mean great turmoil in the power industry, not to
mention our society. What has it meant so far for protection engineering?
We can all appreciate that sustained blackouts lead to public
outcry, which in turn leads to regulations and controls
intended to avert the next one. The famous blackout in North
America of August 14, 2003 led to NERC Recommendation
8a which now restricts zone 3 distance element reaches and
other backup protection on operationally significant lines.
Protection review deadlines were mandated on every utility.
Combinations of government regulation and the NIMBY
(“not in my back yard”) effect have long influenced the type
and placement of large baseload plants. This has encouraged
the proliferation of independent power producer plants,
which are harder to accommodate and protect. Clearly this
PAC.SPRING.2008
Ashok Gopalakrishnan has a
B.E. in Electrical
Engineering with
Honors from Birla
Institute of Technology and Science
in Pilani, India, M.S.
and Ph.D. degrees in
EE from Texas A&M.
He joined Electrocon in May 1999,
and is involved in
CAPE development,
special coordination
studies, mathematical modeling of
protective relays,
macro development, system
simulation and relay
checking studies,
and applying automation techniques
to labor-intensive
projects. He also
worked as an Application Engineer in
the English Electric
Co. of India Ltd. (ALSTOM), in Chennai.
He is a member of
the IEEE.
Increasing
complexity
and additional
governmental
regulations
are today's
reality
by Paul F. McGuire, Ashok Gopalakrishnan,Electrocon International, Inc.,
Anthony T. Giuliante, ATG Consulting Inc.,
Power Systems Analysis
cover story
22
Overcurrent
relay ratcheting
has caused
more than one
misoperation.
combination has yielded boom times for the wind generation
industry. How to model and protect wind farms is a hot topic
in our business. The power of public opinion is exemplified
by a very recent news report from the state of Virginia in
the USA. The state corporation commission overrode the
local utility’s $14 million proposal for a five-mile overhead
transmission line in favor of a $82 million underground
version. The protection engineers involved will now have
the opportunity to develop their expertise in working with
high-voltage cables.
Protection Complexity. We’d like to address one last
force for change that certainly has brought challenge with
it – the increasing technical requirements placed on power
systems have led to a greater complexity of the power
system in general and the protection system in particular.
As population and demand grow, the electrical network
becomes denser and is operated closer to design limits. As
people around the world depend more on electrical energy,
the societal cost of network failure motivates the design of
more robust protection schemes and more of them.
How do we translate this to our experience? It’s easy to
answer this with another question. Back in the early days of
Bob Dylan, who would have dreamed that the half dozen or
so electromechanical relays in a scheme with perhaps three to
four settings each would one day be replaced by one digital
relay offering 100 functions and as many as 9,000 settings?
Who could have imagined setting and testing one of them?
Add to this the many relay manufacturers around the globe,
the fact that each one offers its own software environment
to manage the settings (Vendor software), and the fact that
most of today’s relays require special training to use. Keep in
mind, too, that most utilities purchase relays from at least two
manufacturers. Moreover, the protection schemes themselves
have become more complex. Some form of teleprotection is
often employed, and not just once but twice, as primary and
backup. At this point, one may easily feel compassion for the
dilemma faced by modern protection engineers. What can you
do? Before suggesting solutions, we should mention some
4 Overcurrent relay ratcheting
PAC.SPRING.2008
Vendor Software
mitigating factors to the complexity issue. No utility uses all
the available functions and most settings either don’t apply
to the protection functions directly, or at least do not change
from installation to installation. Those that do are critical, of
course, and must be computed by the protection engineer.
Certainly the cost per function has dropped significantly. Also,
the evolution of digital relay complexity was driven in part by
a demand to solve many different protection issues associated
with various governmental and engineering requirements.
It seems that increasing technical feasibility and competitive
one-upmanship played a role, too. With proper care, these
forces can foster creativity and efficiency.
Possible Solutions
The challenges discussed above are complex. There is
no single, simple solution. In fact, we expect a multitude of
component solutions to become prevalent in the years to
come, and these will affect multiple issues at once. The drain
of experience and personnel continues and is not likely to be
reversed any time soon. The solutions we are able to offer are
aimed at making the best use of the engineers we have.
They may be classified into three broad categories:
Apply new technologies to get the right answers
Use the new technologies to counter the challenge of
diminishing staff and experience
Implement changes in data administration
Apply new technologies to get the right answers
It is often said that protective relaying is both an art and
a science – a science because the engineer can apply precise
rules and techniques in developing relay settings; an art
because, sometimes application of these precise rules does
not quite work. The engineer has to use his or her experience,
judgment, and knowledge of the power system to tweak or
modify the relay settings to meet the desired objective.
23
The changing electric power industry has made these ideas
formulated 25 years ago all the more relevant.
Views of relay
vendor setting
software: Every
relay vendor
offers its own
tools for settings
management.
Therefore, we propose that engineering management
focus on tools and methods that give the relay engineer
confidence that the protection system he or she has designed
will perform as intended. Consider going outside your
departmental staff resources when your workload cannot be
accomplished by existing staff.
Correct your network and protective device models.
The first step in designing a protection system is to ensure that
the power system network is modeled correctly. Most utilities
already have a phasor-based model of their network. It makes
a lot of sense to use this data, verify its accuracy, improve it
where necessary, and develop or evaluate protection schemes
based on it.
Transient network models are very useful in performing
special studies, but require specialized modeling knowledge.
While this expertise is becoming increasingly available at
utilities, familiarity with phasor-based models is widespread.
With phasor-based models, the following issues need to be
addressed:
Modeling of transformers and neutral circuits
Audits on the accuracy of zero-sequence mutual
coupling: Inaccurate modeling of zero-sequence mutual
coupling can lead to incorrect relay settings for ground-fault
protection. Many utilities have performed audits of their
mutual coupling data and uncovered coordination problems
due to missing couplings, reversed signs, and improper
modeling of partial couplings.
Accurate modeling of the network of the neighboring
utilities. This also relates to “Data Administration,” below.
Accuracy of the protection system model: In our
experience, to be able to develop relay settings for the power
system, the engineer must have dependable software models
of relays to work with. That is, the software model of the relay
must be able to capture the behavior of the actual relay, within
the framework of a phasor-based analysis.
This means that realistic comparator equations, polarization
methods, internal supervision, phase selection, tripping and
reclosing rules, and actual settings must be used to simulate
the relay in the network model. When actual setting names are
used, one has a way to share settings with the manufacturer’s
setting software. Traditional analysis techniques might use a
few generic methods for modeling protective devices. This
works well enough for electromechanical and possibly some
static relays, but the multifunction digital relays require more
sophisticated modeling.
Protection engineers are increasingly recognizing the
value of having such detailed relay models for analysis, and
are pushing vendors of analysis tools like us to develop and
supply them. Another advantage of detailed models is their
usefulness in allowing evaluation of a protective device before
actually purchasing it.
Automate relay setting calculations. Once the network
and protection models have been verified as accurate, it is
possible to perform fault studies and develop protective
device settings for the power system network.
The process of developing relay settings can be automated
to a large extent. The computer can be used to perform
large-scale fault studies. The results of these fault studies can
be used to set relays based on specific company-approved
rules and parameters. Where settings of one relay depend on
the settings of a neighboring relay, the algorithm can attempt
to coordinate the two.
Automated setting algorithms should not be expected to
replace the human protection engineer. Instead, they provide
a convenient way of performing routine fault studies and
“first-pass” settings calculations, or can serve as a second set
of eyes reviewing settings calculated manually. However, a
protection engineer may be required to review special cases.
Further, the initial settings computed by the setting
algorithms will need to be tested by performing automated
coordination studies. This could easily necessitate adjustments
in the settings.
Interactive simulations to find miscoordinations.
After verifying the network and protection models and
developing initial relay settings, the engineer will normally
perform interactive coordination studies to ensure that
adequate coordination time interval margins are maintained
between primary and backup devices.
PAC.SPRING.2008
A. Giuliante
"Tony" is the President and founder
of ATG Consulting,
which provides specialized protection
engineering consulting services to
the power industry.
Prior to forming his
company in 1995,
Tony was Executive
Vice President of
GEC ALSTHOM T&D
Inc. - Protection and
Control Division.
From 1967 to 1983,
he was employed by
General Electric and
ASEA. He is a Fellow
of IEEE and has
authored over 50
technical papers. He
is a frequent lecturer on all aspects of
protective relaying,
including electromechanical, solid
state, and digital
based equipment.
Giuliante is a past
Chairman of the
IEEE Power System
Relaying Committee
1993-1994, and
past Chairman of
the Relay Practices
Subcommittee. He
holds degrees of
BSEE and MSEE from
Drexel University.
Power Systems Analysis
cover story
24
Plot of dynamic expansion
of digital
mho element
predicting
operation for
fault near
balance point,
where the
actual selfpolarized
electromechanical relay
operated too
slowly.
Engineers must have tools to
cope with their increasingly
complex environment.
Conduct wide-area coordination reviews. Protective
system reliability can be measurably improved by combining
the unified network and protection system model, detailed
protective device models, and the power of modern computer
technology to evaluate protection system performance to
uncover conditions of miscoordination and, on occasion,
relay design problems. Where such reviews were formerly
considered a worthy but impractical goal, they are now
Interactive simulations may be performed to identify possible and of demonstrable benefit. In one documented
problem areas using the following methods:
case, a wide-area coordination study revealed that 16% of the
Graphically plotting overcurrent and/or distance relay applied faults resulted in a miscoordinated condition. (Figures
characteristics and studying their response to applied faults. 1 and 2) The miscoordinations were mostly due to incorrect
(Figure 6)
settings in the neutral directional overcurrent (67N) and
Looking at device operating times on a one-line diagram zone 2 distance elements. By identifying these conditions,
of the network.
the utility was able to adjust the relay settings and reduce the
It is important to consider faults that test the coordination miscoordination percentage to around 2%.
intervals between protective devices:
One of the interesting results of this study was the
uncovering of a design problem in a distance relay, later
Faults at overcurrent and distance element reach points
verified by an actual misoperation in the field of the same
Faults at mutual coupling separation points
Faults that must be cleared by sequential breaker relay. The cause was unexpected behavior of the polarizing
quantity used by a ground distance element, which only a
operations
Faults in the presence of contingencies like minimum detailed relay model could uncover. This led the utility to
infeed conditions, outaged and grounded mutually coupled temporarily disable the offending element in all the relays of
lines, etc.
that type until a fix was obtained from the manufacturer.
An interactive study with faults applied by hand will give
Use computer tools to respond more efficiently
engineers a very good idea of the coordination problems that to government regulations. In the USA and Canada,
they might face. But the number of conditions to be tested can the aftermath of the August 14, 2003 Northeast blackout
quickly become quite large and impractical to study manually. brought new regulations that utilities had to comply with.
Such simulations may not be adequate and should be repeated One was directed at protection engineers – namely, NERC
Recommendation 8a for zone 3 (backup protection) relays.
over a wide-area of the network, if not the entire network.
Utilities with existing network and protection system models
could easily automate a system-wide review to comply with
Dynamic expansion of digital Mho element the recommendation.
Use computer tools to conduct post mortem
analyses. An accurate, combined network/protection
system model can be a valuable tool for studying questionable
relay operations. In one case we studied, an existing zone 1
relay (an electromechanical design, with a mho-supervised
reactance characteristic) was slow to operate for a resistive
fault. The fault was at the reach limit of the mho supervisor,
which was not designed to use the prefault memory voltage
for polarization. This was verified by subsequent simulation.
Simulations also showed that using a digital relay with
memory polarization would result in fast operation for
the same fault (Figure 5). So proper representation of the
equations behind the relay’s operating characteristics is
necessary.
Use new technologies to address the challenge of
diminishing staff and experience
The methods and tools described above are also valuable
as training tools.
1. Detailed models of protective relays in a master library
can help counter the burden of learning relay details the hard
way, particularly when the model is documented. This serves
as a knowledge base when consulting an expert is not an
option.
5
PAC.SPRING.2008
25
2. Simulating the whole protection system is analogous to
using a flight simulator – a safe environment for engineering
training, and for studying the effect of relay settings on
wide-area coordination.
3. Stored and properly documented setting techniques
can speed the setting and documenting processes, and also
serve as a teaching tool for younger engineers. We aren’t
advocating this training technique as a replacement for the
resident expert but as a supplement and a backup for when
there is no expert.
4. A common database environment can unify and
coordinate the management of settings to a useful degree
without needing to replace the multi-vendor setting software
communication environments - an unrealistic objective in a
competitive world.
5. The application of advanced computer methods, not
only to protection but throughout power system engineering,
can attract prospective engineers to our profession from a
generation already enamored of computer technology.
Implement changes in data administration
Software can’t provide the incentive for organizations
to cooperate, but it can make the mechanics of cooperation
easier. We discuss here some of the advantages that might be
gained by sharing both network and protection data within
different groups in a company and among companies.
1. Data must be maintained by those who use it and who
know the system best, but data could be stored, shared, and
kept secure at a higher level than the individual groups or
their companies. Multi-user database management systems
are common and must not be viewed as a constraint.
Techniques are in use now that support a nearly unlimited
mixture of construction scenarios, generation levels, and
alternative network configurations. Database merge facilities
exist. What is lacking is centralized data storage and sharing.
Formalizing higher level storage and sharing won’t lead to
fewer personnel; in fact, there may be more of a need for
engineering specialists, but it should lessen user tolerance for
marginally adequate network models and overcome the poor
quality neighbor models that are common today. It would
also provide one path for sharing power flow data with the
protection engineers. To the credit of the utilities involved,
there are a number of less formal initiatives now underway to
share short-circuit network models among the participants.
(Planning groups have done this for years.)
2. Share protection system models with planning groups
whose transient stability (TS) and electromagnetic transient
studies would benefit from realistic representation of that
system. Existing TS programs have only rudimentary models
of a few relays, whereas direct links between the protection
system model and the TS time-domain model could lead to
important insights. We also think this would be a positive
step toward increasing awareness of likely protection system
response in operations centers, the lack of which has played a
role in some blackouts.
3. Share protection models with Operations departments
using a link from the SCADA system to obtain actual network
conditions and a link to the SCADA interface to warn of the
threat of load-induced misoperations, to monitor protection
system performance, and to facilitate rapid fault locating
thereby minimizing repair and down time.
6 Dynamic display of primary/backup TOC element coordination
A computer
display can
quickly
present
response
time
changes
as a fault
is dragged
about the
network.
PAC.SPRING.2008
by Christoph Brunner
IEC 61850 update
27
The Life Cycle
of a Standard
An international standard is the
result of the efforts of many experts in
the problem domain that it addresses.
The IEC standardization process is
briefly described bellow. It follows
steps that ensure the coverage of different aspects and the points of view
of participating countries around the
world.
In the last column I
addressed a specific technical
topic related to IEC 61850 – the
modelling of functional hierarchies
as it is currently under discussion
for Edition 2 of the standard. This
time, I will focus on an update
of major activities related to IEC
61850. But in order to understand
the terminology, it might be a good
idea to explain the life cycle of IEC
documents.
An IEC standard is initiated by
an approved new work item. Note
that in IEC, the votes are done by
the national committees that are
member of a technical committee
(TC) – in the case of IEC 61850, the
technical committee is TC 57. Every
national committee has one vote.
Once a work is approved, it is
assigned to an existing working
group, or a new working group is
created to prepare the standard. The
drafts are first circulated internal
to the working group and when a
certain level of maturity is reached,
a committee draft for comment
(CD) is circulated to the national
committees.
A CD is not necessarily yet the
complete and final document. The
purpose of the CD is to show the
direction of the future standard and
to get feedback from a broader range
of experts.
The next step is the CDV –
Committee Draft for Voting.
That is already a mature draft,
the countries have to give a vote
within five month, and the vote can
include comments. If the CDV is
approved, only changes requested
in the comments are allowed and
the next step is the FDIS (Final
Draft International Standard). Here
no technical changes are possible
anymore unless the FDIS is refused
and the document is sent back to
the CDV stage. Shortly after the
approval of the FDIS, the standard
will be published.
Every standard has a
maintenance date. At that time,
the standard can be reconfirmed as
is, withdrawn or a new Edition can
be prepared.Most of the parts that
have been published in IEC 61850
will be issued as Edition 2. With the
Edition 2 we will solve technical
issues (TISSUES) identified during
the first implementations of IEC
61850, but we will address as well
requirements concerning the use of
IEC 61850 in domains other than
substation automation. Edition 2
of part 6 has already been circulated
as CDV, we are currently finalizing
the part 7 (7-1 to 7-4). Part 5, 8-1
and 9-2 shall follow as CDV a few
weeks later. For the other parts we
will prepare CDs.
There will as well some new
parts be added to IEC 61850. I will
report on that in a later issue. For
this time, I would like to point your
attention to the CIGRE conference
hold every second year in Paris.
This summer, the study committee
B5 has selected as preferential
topic 1 "Impact of process-bus
(IEC61850-9-2) on protection and
substation automation systems".
Six interesting papers have
been submitted that are discussing
different approaches for system
architectures when using IEC
61850-9-2 as serial connection
between bay level devices and
current and voltage sensors. If you
plan to visit the CIGRE conference,
this session on Wednesday, August
27, will certainly include many
interesting discussions. And if you
attend the CIGRE conference, do
not forget to visit in the exhibition
the booth of the UCA International
users’ group – the users group for
IEC 61850, CIM and open AMI.
I look forward to seeing you
there!
PAC.SPRING.2008
by Janusz W. Dzieduszko, Quanta Technology, USA
28
Protection Failure
lesson learned
Substation
"Horror
Stories" - a
Manufacturer's
Perspective
Modern Intelligent Electronic Devices, encountered at a substation,
conform to a common architecture:
A processor directs Analog and Binary
Input subsystems to acquire data from
the power system; a Binary Output
provides system control and Communication Subsystem interfaces
to Substation Automation, SCADA
and Energy Management Systems.
The rigid, real time performance demands placed on Protective Relays, Remote Terminal Units, Communication links, SCADA and EMS systems, coupled with harsh
operating environment, make these systems complex to design, install and operate.
This article describes real life episodes as seen through the eye of equipment provider.
1 IED architecture
OPERATOR
INTERFACE
COMMUNICATION
SUBSYSTEM
SUBSTATION
AUTOMATION
PROCESSOR
SCADA, EMS
ANALOG
INTPUT
SUBSYSTEM
PAC.SPRING.2008
BINARY
INTPUT
SUBSYSTEM
Power system
BINARY
OUTPUT
SUBSYSTEM
29
False Breaker Trip Reporting
A Supervisory Control (early
1970’s predecessor of SCADA)
system at a major Electric Utility
reported circuit breaker operations
at several substations occurring at
random, over the span of several
weeks.
Subsequent inspection of the
breaker control equipment at
those substations revealed that no
breaker operations took place and
a Supervisory Control equipment
was providing false information.
Several dozens of these systems
were purchased and installed by
that Utility. Naturally, the reliability of the equipment and the qualifications of the personnel involved in
its design and manufacturing were
seriously challenged by the Utility
management.
It has been mildly suggested during the meeting preceding field investigations that the equipment be
put in perfect operating condition
by the “end of the week” or replaced
with similar product made by those
“who know what they are doing”.
The diagram in Figure 5 depicts a
typical system configuration.
The rest of the day was spent
at the Master Station ( a 90” tall
cabinet full of PC cards with mostly
discrete transistors and indicating
lights). The oscilloscope measurements indicated proper signal levels
suggesting that the problem was
on the RTU level. It is worth mentioning here that the understanding
of the substation noise was rather
sketchy in those days and the equipment tended to be overdesigned.
Similar investigations were performed at the Remote Terminal
Units in question. Oscilloscope
measurements provided no clues.
An MG-6 relay connected in “buzzer” mode was used to generate a
substantial amount of noise; again
no false operations were observed.
As the week came to a close, the
52a wiring (see above) check was
done in desperation. The RTU terminals looked fine; however, a walk
to the breaker control box in the
One of the most
commonly
used methods
of system
troubleshooting is
“board swapping”
yard was very fruitful; the corresponding terminals had loose screw
connections! It was discovered later
that the same problem existed at all
suspected RTU locations. End result: happy Customer !
Lesson #1: Pay attention to the
simplest element of your system
Continuous alarm
The equipment and location
were the same as in the previous
episode. Under normal operating
conditions the alarm or change of
contact status was reported by an
RTU and acknowledged by a Master Station to reset the alarm. The
communication links to the RTUs
were 60mA loops operating at 50
bps (sic!) connected as shown in Fig
ure 2. The transmit TX and receive
RX devices were identical mercury
wetted contact relays with plug-in
octal bases.
One of the RTUs reported an
alarm but the Master Station acknowledgement failed to reset
it, and thus an alarm condition
persisted at the RTU. The system
operator would dispatch a technician to the RTU who subsequently
swapped TX and RX relays, thereby eliminating the problem.
Several days or so later the same
problem would occur, so the same
approach was used and the problem cured again. Note that TX and
RX relays were now in their original position!
During the field trip to the substation, the real problem was determined to be a solder whisker on a
printed circuit board extending to
the adjacent trace, as shown in Figure 4.
During abnormal system behavior with the RTU enclosure sealed,
the internal temperature caused the
solder whisker to expand, touching the adjacent PCB trace and
disabling the alarm acknowledge
circuit. Opening the enclosure to
swap TX and RX relays lowered
the temperature sufficiently to contract the whisker, thereby “fixing”
the problem.
Lesson #2: The “repair” you
just made, may not have anything
to do with the problem!
Printed circuit board
swapping
One of the most commonly
used methods of system troubleshooting is “board swapping”; here
is another real life story.
A second generation SCADA
system, with computer based Master and integrated circuit CMOS
RTUs, was being installed at a medium sized municipal utility. The
system configuration was similar
to Figure 5 with four RTUs on each
communication link. The RTU
conformed to Figure 1, with the
processor section consisting of 3
printed circuit boards: A, B and C.
A portable Master simulator
was used to commission the RTUs.
(Figure 3) Here is the approximate
sequence of events used in initial
troubleshooting:
RTU #1 was verified to perform
properly.
2
Janusz Dzieduszko
is M.S.E.E. graduate
of the Academy of
Mining and Metallurgy in Cracow.
He has over 40
years of experience
in engineering
management and
design in Substation
Automation. Janusz
is currently Consultant with USA
in Raleigh, NC. He
worked with: ABB,
Westinghouse,GE
and BBC. He holds
five patents and is
authored several
papers in Substation
Automation. His biography is included
in Marquis’ “Who is
who in the World”
and “Who is Who in
America”.
60 mA Loop
RX
TX
TX
To Master
RX
To RTU
PAC.SPRING.2008
Protection Failure
lesson learned
30
Be aware
of variables
introduced
during
board swapping.
3 Master simulator
A B C
RTU #1
A B C
RTU #2
RTU#2 intermittently did not
respond to the simulator.
The known reference set of
boards(A,B,C)was inserted in
RTU#2; causing the problem as in
step 2.
The set of boards from RTU#1
was transferred to RTU#2; causing
the problem as in step 2.
The set of boards from RTU#2
was t ransfer red to RT U#1;
RTU#1 checked out OK!
The backplane (motherboard) of
RTU#2 was replaced and the problem still existed as in steps 2,3, 4!
Similar situations were repeated
at other RTU locations.
The careful reader at this moment agrees that some mysterious
events occur at those substations!
Utility engineers reported later
that the manufacturer’s field engineer had five sets of boards and
backplanes in his automobile, and
was driving at 70 mph across town
(from one RTU to another) with a
wild expression on his face!
Here is the real problem as found
many days later:
To operate on a shared communication channel, the RTUs needed
unique addresses. The addressing
was accomplished using a compo-
PAC.SPRING.2008
nent platform with vertical pins inserted in the IC socket. The top pins
were jumpered with the bare wire
and hand soldered. The unused
connections, as determined by address decoding, were clipped off.
It was found that the jumpers
described above had cold solder
connections causing intermittent
problems. Furthermore, these
innocent jumpers were subconsciously removed from the “bad”
boards and transferred to the
“good” boards, always remaining
with RTU#2.
Lesson #3: Be aware of variables introduced during board
swapping.
Intermittent data
communication
A large process control system
as shown on the diagram in Figure
6 was installed. A major computer
manufacturer provided main control processors, SYSTEM 370 and
SYSTEM 7 and software; COMM
INTFCE and RTUs were supplied
by (then) a Major SCADA Company. RTU communication was
via copper shielded twisted pairs
with a maximum distance of 5
km. Asynchronous frequency shift
(FSK) modems operating at 1800
bps, with mark and space frequencies of 1200 and 2200 Hz respectively, were used. Connection was
4 wire with separate pairs for data
transmit and receive. RTU communication used popular 32-bit protocol with 2 start, 24 data, 5 CRC and
1 stop bits. SYSTEM 7 to COMM
INTFCE data link was parallel with
12 bit data lines and several control
lines.
During final system start-up,
a vicious communication problem
was uncovered.
Several (2 to 4) times per day
COMM INTFCE reported CRC
(cyclic redundancy check) errors
on data acquisition; this condition
existed in short bursts of 120 to
180 msec.
System software invoked error
recovery initiating 3 data retrieval
retries and after failure, declared
RTU or communication line “out
of service”. This performance (even
with 99.9992% availability!) was
unacceptable to the user. Considerable time was invested in analysis of
data communication channels. No
obvious sources of suspected interference were found; all vital parameters were well within limits. The
communication FSK modem was
blamed, as 1800 bps operation in
those days was at the cutting edge
of technology. Many adjustments
to compromise delay equalizer
failed to improve the performance.
A legal action with $6 million
liability was suggested at various
management levels.
At that time the author was volunteered to take a look at the problem. From the very beginning he
suspected factors other than those
outlined above.
How do you “catch” the instant
of 120 msec occurring once or twice
in a 24-hour period with sufficient
resolution to decode 555 msec (1
bit time at 1800 bps)? (Remember,
those were the days before logic
analyzers, and storage oscilloscope
was the best tool available.)
Here is the brief description
of a rather lengthy investigation
process:
During a trip to a local audio
equipment rental facility, a stereo
tape recorder and stereo earphones
were obtained and connected to the
communication lines:
After some practice, a rhythm of
“good” and “bad” communication
exchanges was determined. A human ear is an excellent integrator!
Occurrences of communication problems were correlated to
4 Solder whisker
31
5 Typical SCADA configuration
MASTER
STATION
RTU
RTU
RTU
RTU
52a
6
Process control system
SYSREM 370
7
SYSREM 7
COMM INTCE
RTUs
Error sections of tape playback
AUDIO OUT
AUDIO OUT
TAPE RECORDER
RCVR
INPUT
DATA
OUT
FSK MODEM
A
B
OSCILLOSCOPE
PAC.SPRING.2008
Protection Failure
lesson learned
32
the tape counter on tape recorder.
Known sections of tape were
played back as in Figure 7. Normal
data retrieval sequence consisted of
one 32 bit request sent to RTU, followed by up to 8 32 bit responses
from RTU.
Data Request
RTU Response
It was determined that during the
communication problems one
32-bit data request was repeated as
shown:
Data Request
RTU Response
The “phantom” request, shown as
shaded area, was later attributed to
the race condition on the COMM
INTFCE parallel to serial converter
when “write” signal exceeded maximum allowable duration.
As a result the receiver clock
recovery mechanism was disabled
and the incoming RTU response
was received using transmit clock!
No wonder massive CRC errors
were encountered. It was later
determined that the duration of
8
“write” signal was affected by SYSTEM 7 loading. To make COMM
INTFCE immune to variations of
this signal, a monostable multivibrator (one shot) was added, thus
eliminating the entire problem.
The author fondly recalls having
to work 14 hours on the Bicentennial Fourth of July 1976!
Lesson #4: Design your interfaces with care, protect yourself! Do
not be afraid to use unconventional
tools.
Fiber optic noise immunity
Industry’s first Integrated Substation Protection and Control
system was designed as an EPRI
project in early to mid 1980s using
the then state of the art microprocessor 8086 16-bit technology. Due
to processing limitations, (8086
operating at 6MHz and memory
of 128 kbytes) multiple processors
(up to 6) shared the computational
loads and were configured in shared
memory clusters.Figure 8 shows a
simplified diagram of the system.
The Station Computer provided
operator interface for substation
management and was connected to
Protection Clusters via coaxial cable
When things do not
make sense,
you have made
a wrong
assumption!
Data Highway communicating at
1Mbps. Protection Clusters’ function was protection and control;
Data Acquisition Units interfaced
to the power system and were connected via fiber optic Data Links
operating at 1Mbps to Protection
Clusters.
Fiber optic Clock and Arbitration Bus synchronized the system
and allowed for intercluster communication for time critical control operations.The system was
designed with interoperability in
mind 20 years before IEC 61850;
the elements shown in dotted lines
were provided by another manufacturer and were successfully integrated into the system during final
installation at a major 500 kV sub-
Simplified diagram of the system
XFMR
Protection clusters
BUS
LINE
data highway
Station Computer
data links
Clock & arbitration bus
500 kV
Yard
DAU
Data acquisiton units
PAC.SPRING.2008
33
station.In the final phase of testing
at the factory, the system suddenly
started to “crash” several times per
day.Extensive use of fiber optics
assured very high degree of noise
immunity, thus exonerating system hardware.The interaction of
multiple processors in clusters was
suspected and analyzed over the
period of days; no obvious reasons
were found.
It was observed later that the
crashes occurred during late morning, and were later correlated to the
passing of a Mail Robot vehicle near
the system. The vehicle has a motor
that generates EM interference; the
system hardware became a prime
suspect. Very soon the problem was
solved:
A robot (in addition to motor)
had a safety strobe light that was
penetrating one of the Protection
Clusters via partially open enclosure rear door. These light pulses
were “read” as spurious interrupts
by a fiber optic receiver left open
for the integration of other manufacturer’s cluster into the system. A
strategically placed piece of electrical tape cured the problem.
Lesson #5: Do not take anything for granted.
False system operations
Some time following successful
installation and integration at the
substation, the system described in
the previous chapter began to issue
false breaker trip commands.
These occurrences were rare
(2 to 3 weeks apart), random, and
were traced down to all protection
clusters. Obviously, much energy,
time, and money was invested in
attempts to eliminate this unpleasant phenomenon. The complexity
of the system opened the door to
various theories in two basic areas:
Substation noise
System software bug
The system passed extensive
factory type testing including
SWC, Fast Transient, RFI and temperature limits.
Massive utilization of fiber op-
tics for system interfaces eliminated
a wide area of suspicion. The system was designed by software and
hardware engineers with vast experience in substation requirements.
Software “traps” were added to
the system, logic analyzers initialized to trigger on suspected events
were installed, and additional filtering and shielding were tried; no
answers were obtained. The last element analyzed by the author was
Analog Input card in Data Acquisition Unit. (Figure 9)
The microprocessor controlled
the A/D conversion process, and
using precision REF inputs, provided continuous A/D calibration
for temperature and component
tolerance drifts.
The calibration was in the form
of: Where y – A/D output; a – gain;
x – Analog input; b – offset.The
A/D had 16-bit output, while the
microprocessor was 8049 family 8-bit machine. All arithmetic
operations were, therefore, using
double precision arithmetic (low
byte, high byte).
15
7 High byte 0 7 Low byte
And a quote from the
past:
“Omnia autem probate
quod bonum est
tenete.”
“Prove all things;
hold fast that which is
good.”
I Thessalonians 5:21
A rms) for analog inputs. It is easy
to compute that the input of approximately 20 mV (0.585 A rms)
sets bit 7 of LOW BYTE to a “1”,
thus causing the false assumption
of a huge fault current (equal or
greater then 30 p.u.) and subsequent system trip.
Lesson #6: Pay attention to
processor architecture. Avoid fixedpoint arithmetic.
0
0
The assembly language programming was used.Taking the
program listings and processor reference manual home, away from
the day to day distractions, after
several hours of careful instruction
by instruction study, the resounding EUREKA! followed.
It was found that doing ax + b
addition, the processor checked
for possible register overflow (i.e.
the result possibly exceeding 15 bit
number).
Bit 7 of HIGH BYTE set to “1”
indicated that fact, and should result in setting the register to full
scale (7FFFhex).
Instead of testing that bit, bit
7 of LOW BYTE was tested in error (otherwise known as software
“bug”).
Full scale input to the A/D was
5 V corresponding to 30 p.u. (150
9
Analog Input
FIELD
INPUTS
A/D
MUX
REF
µP
PAC.SPRING.2008
system
power
outages
by Clare Duffy, ESBI, Ireland
34
Florida, USA
26 February,
2008
Watch
blackout
St. Andrew,
Jamaica
6 April,
2008
Analysis of system power outages can help us learn
and avoid similar events in the future. If you have
information on any blackouts, please e-mail to:
http://editor@pacw.org
PAC.SPRING.2008
A blackout that struck Carcar City
and 16 towns in southern Cebu was
caused by the torching of a 69 kV
wooden electric pole that created a
“domino effect” and brought down
with it two other nearby poles. The
power outage lasted nearly 14 h.
A blackout hit Cape Town at 8.45
PM on Friday and lasted until the
early hours of Saturday. Eskom
apologized to its customers for the
technical fault involving a conductor
at the major subst at ion of
Muldersvlei-Acacia, plunging most
of the city into darkness.
Human error was the cause of a
state-wide blackout that started at
1:09 PM and affected about 584,000
FP&L customers and an additional
half-million across three other
utilities. It began with a field
engineer diagnosing a switch that
had malfunctioned at a substation
in West Miami. Against company
rules he had disabled both the
primary and backup protection. The
fault affected 26 transmission lines
and 38 substations. One of the
substations affected serves three of
the generation units at Turkey
Point, including a natural gas unit,
as well as both nuclear units, which
Karachi,
Pakistan
26 February,
2008
South Africa
Cape Town,31 March,
South Africa 2008
1 February,
2008
shut down automatically. Two other
generation plants were affected and
the system lost a total of 3,400 MW
of generating capacity.
A row over unpaid bills sparked
a huge power blackout in Pakistan's
biggest city, Karachi, leaving most
of its 12 million residents without
electricity. The outage came after
Pakistan's main power utility
New Delhi,
India
16 March,
2008
accused the electricity company
supplying the southern port of
refusing to settle debts of more than
half a million dollars.
Following a blackout that lasted
several hours on 14 March, Delhi
and its satellite towns were
subjected to another power
shutdown on the morning of 16
March, as more than thirty seven
400 kV transmission lines tripped.
Most parts of West, East and North
Delhi experienced prolonged
power cuts. The tripping of lines
was blamed on flash-over on the
insulators in the presence of fog and
pollutants in the atmosphere.
Residents in Kingston and St
Andrew were left w ithout
electricity for close to four hours
after a fault with one of the
company's transformers triggered
the outage. A zonal strategy saved
Jamaica from another island wide
power outage.
South African power utility
Eskom will start nationwide
planned blackouts from March 31
Manila
Philippinies Carcar City,
11 April, Philippinies
2008
30 January,
2008
to reduce demand, as Africa's biggest
economy st r ug gles w ith an
electricity crisis. The utility said it
would implement rolling blackouts
- known as load shedding in South
Africa - for at least three months to
reduce electricity demand to
manageable levels.
Shortly after 9 AM a falling
construction crane cut an electricity
transmission line and plunged most
of the Philippine capital into a
three-hour blackout Friday, affecting
about 70 percent of metropolitan
Manila and triggering an automatic
shutdown at several power plants.
The outage halted trains and
disrupted traffic, leaving commuters
stranded throughout the city.
Thieves apparently looking for
scrap metal triggered a blackout
across most of Sabah state in eastern
Malaysia when they removed iron
beams from a 132 kV tower, causing
it to collapse and triggering a
domino effect that left 300 thousand
customers in the entire state of
Borneo Island without power.
PAC.SPRING.2008
Kuala Lampur,
Malaysia
21 April ,
2008
Time and
location of the
System & Power
Disturbances in
2008
by Javier Amantegui, Iberdrola Distribution, Spain
Challenges
System Protection
36
I believe
that the only
solution to
the problems
is a black-box
approach.
Challenges
and
Opportunities
utilities face by using modern
protection and control systems
Before considering the application of relays, we should
answer a basic question:
What is the main requirement for protection from the
utilities’ point of view? In my opinion, there is no doubt that
reliability is the main requirement.
When there is a fault in the grid, everybody expects relays
to trip quickly and with selectivity no matter the kind of fault
or the initial cost of protection.
According to a survey carried out in eight utilities by
the CIGRE Task Force 34.06 (2002), reliability indexes
were between 92% and 97.5%. The three utilities with
the best indexes, above 97%, had carried out an extensive
refurbishment program of their protection system.
Although this may seem obvious, it must be emphasized
that refurbishment is the easiest way to achieve protection
reliability improvement.
There are two main drivers for refurbishment:.
Measurement Equipment
The measurement equipment used is as follows:
Increasing protection requirements are coming from
the grid. For example, in the case of Spain there has been an
1 Human Machine Interface
PAC.SPRING.2008
pictures courtesy to :
Iberdrola
increase in load of 32% in the last seven years. This increase
has resulted in a reduction of critical clearing times and new
requirements for protection.
Protection assets are becoming older. According
to aforementioned CIGRE Task Force, 40 to 50% of the
protection relays of some utilities were electromechanical
and more than 30 years old.
Taking these two facts into account, we must think of
protection as a strategic asset that should be able to cope
with more and more demanding requirements from the grid
now and in the future. In order to achieve this, state of the
art protection systems will need to be installed in the grid.
But let’s go even further -- improvements in reliability
that can be obtained from new digital relays. According to
Iberdrola’s experience with causes of protection failure in
new substations, only around 15% of the failures are internal
to the relays. However, 40% of the failures are outside the
relays, mainly due to wiring. and 45% of the failures are
caused by setting errors. The good news is that 85% of these
failures could be eliminated by the utility.
Consider the three main ways to achieve reliability
improvement:
Standardization: in order to reduce engineering and
construction errors.
Commissioning testing: in order to identify and correct
these errors.
2 IED Panels - 1/2
37
Fault analysis: in order to detect any faulty operation
Modern protection and control systems offer new
opportunities for improvement in these three approaches.
Here are examples of best practices:
Standardization
Red Eléctrica de España (REE), which is the TSO in Spain,
is carrying out a very ambitious protection refurbishment
campaign in the whole transmission system. The key to
achieving their goal is standardization and wiring reduction.
This standardization has allowed REE to increase the
reliability of their protection system and to fulfill deadlines
with their refurbishment program.
Commissioning testing
New devices based on IEC 61850 allow for new
functionality. Therefore testing can be carried out directly
from the configuration files of the substation and completed
automatically. This opens new opportunities to reduce
testing time and more efficient identification of failures.
Fault analysis
These days, with new digital protection, the problem is
not having the information, but how to deal with it.
In this respect, we think that protection management
systems are crucial. The system we are using in Iberdrola
covers the functions of communication with relays, fault
analysis tools, setting database and fault database. This
system is the heart of our protection organization and helps
us to achieve our goal of attending and correcting significant
protection failures in 24 hours.
A second step would be to develop analysis tools to
automatically help the engineer with a diagnosis. However,
in order to do this, standardization is essential
It’s clear that digital technology offers new opportunities
for improvement; there are also several drawbacks, related
with people. Protection engineers have difficulties with the
new protection constraints such as:
Complexity. A modern relay usually has 200 or more
parameters to be adjusted.
3 Substation Mercedes
Relays become obsolete quite rapidly. And within the
life span of each relay, versions are changed several times.
Version control is probably the main problem with digital
technology.
Protection people need new skills to deal with
Information Technology. For example, in the past it was
quite easy to change a wired signal connected to a relay.
Now, to change the configuration of a multi-vendor SAS
could be a really complex task.
Of course, there are also the well-known constraints
of less commissioning time, fewer resources and difficulties
to recruit new staff; but these are not only related to digital
technology.
How can we solve all these problems? I believe that the
only solution is a black-box approach. Protection engineers
should be able to work with different models of relays in a
conceptual way. We should be able to work using the same
tools and with the same functional models. This will allow
us to gain experience and give added value to our work.
Please try to focus on this basic knowledge and try to avoid
spending time with details that will be useless in the short
term.
Going back to the improvement based on standardization,
in Iberdrola we think that the key to this approach is
standardization based on IEC 61850. That is the reason why
we have developed a multivendor IEC 61850 based SAS.
The first substation was commissioned last year and this
year we have three new IEC 61850 substations projects.
In conclusion, my opinion regarding the application of
digital protection and control by utilities could be summed
up in two ideas:
Protection is the strategic asset to support the new
requirements and constraints on the grid, now and in the
future.
Protection engineers have never before had so many
and such challenging opportunities to improve reliability.
4 Wind farm
PAC.SPRING.2008
Biography
Javier Amantegui
Javier Amantegui
graduated as an
electrical engineer
from the Escuela
Superior de Ingeni­
eros de Bilbao. He
joined Iberdrola in
1997 and worked in
the areas of SCADA
hardware mainte­
nance, protection,
power quality and
metering. At pre­
sent he is manager
of the Protection
and Technical Assis­
tance Department
in Iberdrola Distri­
bution in Spain. He
has been involved
in CIGRE activities
since 1988 and he
will be the new
SC B5 Chairman
from August 2008
onwards.
Precise
by Dr. Juergen Holbach and Michael Claus, Siemens PT&D, USA
38 39
Fault Locator
with two-end
phasor measurements
EAF
Transformers
Fault locator functionality is a standard feature in modern numerical feeder
protection devices for transmission systems. It is common practice to calculate the
fault location via an impedance measurement separately at each line end. All
calculation techniques used to date in this “single ended” fault location approach
exhibit limited accuracy.
Hereafter, the fundamental improvement provided by
the “two ended” fault locator,
which in addition uses the
measured values from the
opposite line end, are described.
Single-ended fault locators are normally based on an impedance
measurement. Only the fault reactance is used to determine the
distance to the fault. The distance protection is based on the same
principle. All protection engineers know about the limitations of this
measurement and use only 80-90% of the line impedance for a zone
1 setting. Even more difficult for the fault locator is, that an accurate
measurement is expected along the whole line and not only on one
PAC.SPRING.2008
by Dr. Juergen Holbach and Michael Claus, Siemens PT&D, USA
setting point like on the distance protection function.
This is especially a challenge for lines with a non linear
impedance distribution along the line.
In the diagrams of figure 1 is an evolving fault shown
on a 50 miles long line. The fault was at 5 miles from the
shown location. The figure shows the signals of a C-G
fault on the parallel line with a BC evolving fault on the
actual line after approx 2.5 cycles.
The fault locator result from the single ended fault
location from both ends (red) and the double ended fault
locator (blue/green) are presented in Figure 2.
The common factors that influence the accuracy are
described below. Hereafter, the fundamental improvement
provided by the “two ended” fault locator, which in
addition uses the measured values from the opposite line
end, are described.
Factors that influence accuracy of “single-ended”
fault locator
In the following the most important error sources for
the result of a fault locators are listed.
1. Residual Compensation (ZG/ZL, k0)
The majority of the short circuits that occur in the
transmission system are ground faults. The accuracy of the
“single ended” fault location largely depends on the zero
sequence compensation setting for the ground impedance
when the short circuit involves ground. The exact value of
this compensation factor is often not known. Even if the
ground impedance of the line is determined by measuring
the zero sequence impedance prior to commissioning –
which is usually not done due to time and cost constraints
– the actual effect of ground impedance during the short
circuit may be severely dependent on the actual fault
Dr. Juergen
Holbach
was born in
Germany in 1961.
He graduated from
the University of
Berlin with a PhD
in Electrical Engineering. He joint
the Siemens AG in
1992 as a development engineer in
Berlin Germany. In
1994 he moved to
the product management group for
protection relays
in Nuernberg
Germany. Since
2000 he works
for Siemens in the
US out of Raleigh
North Carolina.
1
location. The effective ground impedance is often not
proportionally distributed along the line length, as it
may vary significantly depending on the consistency of
the ground (sand, rocks, water, snow) and the type of
grounding applied (tower grounding, parallel cable screens,
metal pipes).
2. Parallel lines
In the case of parallel lines, inductive coupling of the
current circuits is present. On transposed lines, only the
zero sequence system is negatively influenced by this
coupling. For load and faults that do not involve ground,
the influence of the parallel line may be neglected. With
ground faults in the other hand, this coupling may cause
substantial errors in the measurement. On a 400 kV double
circuit overhead line measuring errors at the end of the
line may for example be as large as 35% /1/ Some devices
with distance protection functionality have a measuring
input that may be applied to measure the ground current
of the parallel line. With this measured ground current of
the parallel line the impedance calculation may be adapted
such that the parallel line coupling is compensated. This
parallel line compensation can however frequently not be
implemented.
The reasons for this are that only a section of the line
is in parallel to another line, two or more parallel lines
exist or the connection of current transformer circuit
between individual feeder bays is not desired by the user
for operational reasons.
While the selective distance protection function
can still be implemented by appropriate zone setting in
combination with teleprotection systems, the results of
the fault locator without parallel line compensation is
often not satisfactory.
2
Currents and voltages
signals of a C-G fault on the parallel line and
BC evolving fault on the actual line after 2.5 cycles
Fault locator results
from single ended fault location from both ends and
double ended fault locator
I/A
20
0
-20
-40
double-sided: Type=L2L3, Location=5.0 miles, If=19.6 kA, Rf=0.1 Ohm
single-sided (K2): Type=L2L3, Location=4.4 miles, If=19.6 kA, Rf=0.4 Ohm
single-sided (K1): Type=L2L3E, Location=5.4 miles
20
0
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
t/s
-20
I/A
-40
20
Current IA
U/V
Current IB
Current IC
K1:Strom iL1
0
50
K1:Strom iL2
K1:Strom iL3
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
-0.02
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
t/s
-20
0
-40
-50
Current IA
Current IB
t/s
Current IC
-100
U/V
20
0
-20
-40
50
Voltage VA
Voltage VB
Voltage VC
0
-0.06
-0.05
-0.04
-0.03
t/s
-50
-100
Voltage VA
Voltage VB
Voltage VC
K1:Spannung uL1
PAC.SPRING.2008
K1:Spannung uL2
K1:Spannung uL3
10
9
8
7
6
5
4
3
2
1
0
Evaluation
Fault Locator
analysis
40
I
1
I
2
K1: double-ended
I
3
I
4
I
5
I
6
I
7
I
8
miles
K1/K2: single ended from both ends
by Dr. Juergen Holbach and Michael Claus, Siemens PT&D, USA
41
A new approach for fault
locator is developed
for relays with
a communication link
between each other.
3. Tower geometry and transposition of the
conductors
The geometry of the overhead line towers as well as the
phase conductor transposition technique may introduce
impedance measuring errors of up to 10% /1/. Extra
high voltage lines in transmission networks are often
symmetrically transposed with 3 sections. In total, the
same impedance for each phase is then approximately
achieved for the whole line length. This influencing factor
on the accuracy is in this case kept within an acceptable
range. In HV systems however, non-transposed lines may
be found on short line lengths due to cost constraints.
4. Fault resistance in conjunction with two ended
in-feed and load flow
Transmission of load across long transmission lines
results in a phase displacement between the voltages V1
and V2 at the two line ends (Figure 5).
In the event of a short circuit, the EMFs (Figure 5)
feeding onto the fault will therefore have different phase
angles. In a first approximation, the short circuit currents
from the two ends are also displaced by this angle. The
short circuit current flowing from the two line ends
through the ohmig fault resistance RF causes that the
relays will see the fault resistor as resistive and inductive
impedance due to this phase displacement.
At the line end that is exporting the load, the measured
reactance is reduced, the phasor (I2/I1) RF is rotated
downwards (Figure 5). At the line end that is importing
load, the measured reactance is increased, the phasor
(I2/I1) RF is rotated upwards. The smaller the phase
displacement between the currents I2 and I1 is, the
smaller the influence on the measured reactance will be. In
the case of an unloaded line, the EMFs and the currents at
both ends are in phase. This assumed that the angles of the
fault impedance loop are equal on both sides of the fault,
which is on transmission lines normally fulfilled. On faults
without ground, the fault impedance will be measured
only with an additional resistive part what will not effect
the result of the fault locator.
On fault involving ground the method of the zero
sequence compensation can effect the reactance calculation,
and therefore the fault locator accuracy. By using zero
sequence compensation methods which compensate the
loop reactance and the loop resistance separately, a poorly
ohmic fault resistance on an unloaded line will not cause
a calculation error for the reactance. If a complex zero
sequence compensation factor is used, the fault resistance
is seen as a complex impedance and the reactance
calculation which is important for the fault location will
be influenced. The compensation using a complex zero
sequence compensation factor is only correct for metallic
faults.
The effect of the fixed resistance on the reactance
measurement may be compensated to a degree with the
single-ended fault locator based on certain assumptions.
23
24
Infeed from both ends
Double circuit transmission line
At the line end the measured reactance is reduced and
RF is rotated downwards
ILoad
ZLA
IA
ZLB
RF
IB
VA
VB
Line impedance
Faulr resistance
Voltage
PAC.SPRING.2008
Michael Claus
was born in Wuerzburg Germany in
1960. He graduated
from the University
of Hannover with a
master in Electrical
Engineering. He
joint the Siemens
AG in 1988 as a development engineer
in Berlin Germany.
In 1991 he moved
to the product
management group
for protection
relays in Nuernberg
Germany. He is the
product manager
for the world wide
Siemens distance
relay business.
Fault Locator
analysis
42
The financial
returns for
the company
are optimised
The fault location
becomes calculated with
the processing of the
synchronised current and
voltage vectors from both
sides.
Some solutions require setting the source impedance
parameter. This can however not be considered as a
constant in most cases, so that this technique is not
recommendable. Other principles are based on delta
quantities; these utilise the load conditions prior to the
short circuit. The results are however only correct if the
system topology and the load current do not change
during the short circuit condition. This also does not
always apply. Other solutions include a load compensation
for single phase to ground faults. This technique assumes
that the ratio of X0/R0 – and therefore the angle of the
zero sequence impedance- to the left of the fault location
is the same as the ratio X0/R0 to the right of the fault
location. In EHV systems this is often the case. Close to
transformers this assumption will however also result in
inaccurate result from the fault locator.
Fault locator using measured values from both
line ends
Direct digital communication between relays not only
facilitates the exchange of protection data, but can also
introduce a significant improvement of the fault location.
The advantages of the “two ended” fault locator are:
The fault location of resistive fault is, independent of
the load current and line length accurate.
The algorithm only utilises the positive and negative
sequence impedance. The zero sequence impedance is no
longer required for the fault location calculation in the
event of ground faults.
The influence of inductive coupling from parallel
feeders may be neglected.
Non-symmetries due to the absence of line
transposition and the combination of different tower
geometries may be compensated for.
Selection of the measuring data window
For accurate fault location computation the currents
and voltages must exhibit as steady a state as possible. The
selected data window may therefore not contain any abrupt
changes due to fault condition changes or switching. For
the fault location computation, a data window containing
at least one but not more than three cycles of sampled
values is used. The data window selection is carried out
automatically by the algorithm. In the event of system
disturbances that cause tripping by the device, the data
window is positioned around the instant of the trip
command. It ends shortly after the circuit breaker opens,
immediately prior to interruption of the current. The start
of the current and voltage data window is positioned such
that the length of the data window is preferably three
cycles without any abrupt changes of the current wave
form. In the event of very short system faults, or short
intervals until the fault condition changes, the measured
window may be as short as one system, cycle for the
by the higher
availability of
the overhead
15
Phase shift between the sources voltages and fault currents
line due to
a = IA + IB - IA
shorter down
times and
X
VA
VB
VARC / ISC1
1 + K0
consequently
the improved
ZL1
IA
transfer
capacity of the
R
network.
PAC.SPRING.2008
IB
43
computation. (Figure 6) Sometimes it is also desirable to
indicate impedance measured value and fault locator data
when there is only a fault detection by the protection
and no trip command. In this case the data window is
positioned at the end of the first fault detection data
window. The end of the first fault detection data window
is either determined by the re-set of the protection fault
detection or by a change of the fault type.
Synchronisation of the phasors
The “two ended” fault locator uses current and voltage
phasors of all three phases from both line ends. The
numerical filters are designed so that the fault location
calculation is done based on the fundamental component.
The current and voltage phasors are provided with a time
stamp, the actual system frequency and data window
length information is added and then transmitted via the
digital communication link to the corresponding device
at the other line terminal. Protection device A therefore
receives the values from protection device B and vice versa.
With the time stamp, system frequency and data window
length the phasors can then be synchronised to a common
reference. Using the time stamp, the phasors are then
checked to see if they belong to the same condition during
the system disturbance.
Only if they both refer to an identical interval of the
fault will the computation based on the “two ended”
method be done.
Two ended fault locator computation with
positive and negative sequence values
The here presented two ended fault location is based on
the principle that the voltage decays along the line up to
26
Positioning of the data window
after trip by protection
Relay pickup
I/A
the fault location. By means of the currents and voltages
measured at one line end, the voltage along the line may
be calculated using an RLC line model. If the cause of
the voltage is now calculated from both line ends, a fault
location may be indicated at the location where both
voltages have the same value. In Figure 7 this is given by
the intersection of the two curves.
To achieve high accuracy also for long overhead lines
and cable sections, the voltage calculation is done based
on the homogenous line impedance. The relationship of
voltages and currents is given by the hyperbolic function
( )
( )
V (x ) = V m ⋅ cosh g ⋅ x − Z ⋅ I m sinh g ⋅ x
whereby:
voltage at the position x
measured value at the corresponding line end
distance from the beginning of the line
propagation constant of the line
V (x )
Vm, Im
x
g
The 4 decisive advantages of this
“two ended” method are:
Not influenced by inaccurate ground impedance
Relay trip
CB open
Prefault
condition
The location of the fault
can be found much faster due
to the increased
precision of the fault
location output.
The time that the feeder is
out of service is reduced.
compensation factors (XG/XL, RG/RL, k0)
Jump B
Not influenced by fault resistance on long
heavily loaded lines.
Fault inception
1.48
1.5
1.52
1.64
1.56
1.58
Jump A, C
1.60
1.62
Negligible influence by parallel lines.
1.64
t/s
Reduced influence due to non-symmetry of
Jump
Jump Data window extension
before trip command
Current waveform
Fault inception
non-transposed lines.
Breaker open
PAC.SPRING.2008
by Dr. Juergen Holbach and Michael Claus, Siemens PT&D, USA
44
Fault Locator
analysis
g=
Z
(R'+ jwL')⋅ jwC '
characteristic impedance of the line
Z=
R'+ jwL'
jwC '
At the fault location, the voltages calculated from both
ends of the line must be the same.
The set of non-linear equations is solved by determining
the smallest voltage difference:
whereby:
e (x ) = V ⋅ (x )− V (x )
e (x ) error voltage (ideally equals zero)
V l (x ) course of the voltage calculated from the left hand
line terminal
V r (x ) course of the voltage calculated from the right hand
line terminal
Using proven mathematical techniques the fault
location can be determined by means of the sum
of the least squares in the symmetrical component
system (least-square’ estimation according to ClarkeTransformation)/2/.
The measuring technique contains several plausibility
checks. They are:
Faulty or missing communication telegrams are
detected and eliminated
Measured values that deviate extensively from the
sinusoidal wave form are detected and not used for the
fault location computation. A CT saturation detector
additionally ensures that no gross errors in the fault
locator are indicated.
Short circuit locations outside the protected feeder
can by principle not be calculated by the two ended
technique.
Non-symmetrical overhead lines
In connection with the fault location calculation it is
often neglected to consider that the individual conductors
of the three phase system are not spaced equally with
respect to each other and ground. It is generally assumed
that the impedance in all three phases is the same. By
neglecting the existing physical non-symmetry of
the conductors, the fault locator result will in practice
vary, depending on the faulted phase. Ideally, the nonsymmetrical inductive coupling between the three phases
should be considered in the fault location algorithm.
Setting all six coupling impedances would however be
very complicated and not practical for the user.
In the two ended fault locator there is therefore
a function that allows for the non-symmetry of the
impedances of a non-transposed overhead line. When
commissioning the fault locator, the central conductor
must be defined.
Particularly good results are obtained with tower
geometries having horizontal or vertical conductor
spacing. In the following diagram the “central conductor is
Phase B. If the conductors are properly transposed (refer to
3) no central conductor is defined.
17
18
l
r
Conductor arrangement
on HV towers
Voltage along the line from
both sides
The fault
IA
R'
locator
provides the
user with
Multiple ground faults at different locations on the
protected feeder can by definition also not be calculated
with the two ended method.
Only when the measured results are plausible, will
the two ended fault locator indicate a result. To provide
the user with some assistance in locating the fault,
an indication based on the single ended impedance
measuring technique which is similar to the distance
protection measurement, is provided.
X'
R'
C'
C'
VA
X'
IB
A
B
d
C
VB
RF
B
C
d
B
C
dA
VA
A
A
d
dA
dA
VB
substantial
VA(x)
advantages.
VRF
x
Line impedance
PAC.SPRING.2008
VB(y)
y
Faulr resistance
Voltage
Non - symmetrical
Phase conductor
Symmetrical
by Dr. Wolfgang Wimmer, ABB, Switzerland
Designing IEC 61850 systems
for maintenance, retrofit and extension
The goal of IEC 61850 is to support arbitrary system configurations with
centralized or decentralized architecture. The choice of a specific system architecture
is beneath pure technical aspects determined by the existing products and proven
solutions. As technology advances, other kinds of architectures may become usable
and cost optimal, which lead to a different amount of IEDs and a different internal
structure of them, which is reflected in the IED related identification of data. On the
other hand, low effort long term maintenance needs identical names for identical
objects. But even at the replacement of an IED by a functional equivalent IED from
another manufacturer a different internal structuring and naming is most likely.
Engineering
IEC 61850
46
Usage of names
Names are used at system
engineering time to establish
relations between the different parts
of the system: Relations between
the switch yard (primary system)
and the IED signals (secondary
system), and data flow between IEDs
for communication engineering
respective online communication
association establishment. A name
change at a data source therefore
leads to reengineering of all IEDs
connected to the changed one
respective replaced one. In former
master slave architectures all data
flowed between the bay level IEDs
and one single central place, only
the IED to be replaced and the
central IED were concerned. For
IEC 61850 however already for
availability reasons several station
level IEDs might be connected to
the same bay level IEDs, and the new
Wolfgang Wimmer works for ABB Switzerland in Baden. He
is principle engineer in the development of substation automation systems. He has a M. Sc. degree as well as a Ph.D. in
Computer Science from the University of Hamburg. After some
years developing Computer networks at the German Electron
Synchroton DESY in Hamburg he changed to ABB (former BBC)
for development of train control systems, later Network Control Systems. He has more than 20 years experience with development of substation automation systems. He is a member of
IEC TC57 WG 19 and WG 10, and editor of IEC 61850-6.
PAC.SPRING.2008
communication services GOOSE
and SMV (Sampled Values) allow
new substation functionality or
existing functionality with less
engineering effort and higher
reliability, however introduce
multiple sinks for certain signals,
which might be concerned by
a change at the signal source, as
illustrated in Figure 1.
IEC 61850 object types and
data identification
IEC 61850-7 introduces IED and
communication modelling concepts,
and standardized data semantics
by standardized names. However,
the concrete instance names are
additionally dependent on the
physical and logical structuring of the
data and therefore not a priori stable
when replacing IEDs or changing
the architecture. What is long term
stable (as least as long as the switch
yard itself), is the functional meaning
of the data in relation to the switch
yard respective the power delivery
process. Further the substation
automation functionality related
to the switchyard is normally long
term stable, although extensions
are not excluded. Therefore IEC
61850-6 introduces a second way of
identifying the same data, namely by
functional designations as defined in
IEC 61346.
IED related objects and
their identifications
IEC 61850 as a communication
standard in first line addresses data
identification at communication
level, i.e. at interface level between a
server or publisher IED and the data
receivers (clients, subscribers). To
make this naming independent from
the physical structure, the concept of
a logical device (LD) is introduced as
a management unit for functional
parts. Figure 2 shows the resulting
internal structure of an IED. The communication function
uses IED access points to connect
clients with servers. In principle
each logical node can be a client to
other logical nodes on some server.
IEDs which only receive data, like
the OPC server AA1KA1 in Figure
1, can also be pure clients without a
server.
To reach the goal of having
standardized semantics, the DATA
names as well as the names of
DATA attributes are completely
standardized. Also the semantic of
the logical nodes is standardized by
means of a logical node class, which
is part of the logical node instance
name. A real system needs instances
of logical node classes, which are
associated to different parts of the
switch gear; therefore the LN instance
47
identification has non standardized
parts. The logical device name as
a manufacturer / organisation
related structuring is completely
free within some syntactical limits.
This is illustrated in table 1 with an
example designation for a switch
position value within the switch
control function:
MyControl LD1/Q0CSWI3.Pos.
stVal
A product manufacturer typically
provides IEDs as products with
some predefined functionality,
however with no context to the
project specific usage. Therefore the
LD relative name and some parts of
the LN instance identification need
to be given by the manufacturer
independent of the unknown
project, and might be needed after
project engineering to associate the
project specific data to the project
independent preconfiguration of
the IED. Therefore it is manufacturer
dependent, which parts of the
LN instance identification can be
adapted specifically for a project.
Although this designation is
mainly used for communication
establishment, we might call it a
‘product related’ designation in the
sense of IEC 61346-1, especially if
the IED designation is used as part of
the LD name.
From this discussion we see
how the physical architecture
influences the communication
level naming. Table 2 illustrates
this with two logical nodes for
the control function: the CSWI
handling control commands
from the operators and the XCBR
executing these commands at the
circuit breaker. The architectures
referenced in the table are illustrated
in Figure 5.
Consequence: different physical
architectures by grouping on IEDs
as well as different organisational
structures by means of logical
devices lead to different names, even
if an IED and its tool supports free
naming for the non standardized
parts. And the free naming is not
mandatory according to IEC 61850,
and naturally introduces additional
engineering and testing effort –
especially at LN instance level.
Function related objects
and identifications
According to IEC 61346 the
functional designation is at least as
important for operation of a process
as the product related naming for
maintenance. IEC 61850-6 therefore
introduces application related
names of data by typically following
the functions of the switch yard,
however allowing additionally (with
Usage of application
oriented functional
names in parallel to
maintenance
related IED names
with automatic
translation via
SCL files, enhances
long term system
maintainability
Edition 2 practically at all places)
functions which are not directly
switch yard related, like protection,
control and automation functions,
but also supervision functions
outside the substation function itself
like fire supervision, or functions
belonging to power generation. The
functional names are completely
project / customer specific within
the structural restrictions given by
IEC 61346-1. The transition object,
i.e. the place where product related
name and function / application
related name matches the same
Figure 1
of a small
StatUrg
StatUrgC1
Color code:
GOOSE
interlocking
system
reasons, the
controllers
exchange
GOOSE
messages.
The
replacement
1 Data
flow between IEDs in the substation
Example of a small system with an OPC server & a gateway as station level IEDs
AA1KA1
OPC Server
P2WA1
For
an example
of IED P2KA1,
Unbuffered
influences
3 other IEDs.
P2Y1
COM581
***GW***
StatUrgC1 P2KA1
REC 670
StatUrgM1 P2WA1
MeasFlt
The four
Interlock
P2KA2
C264
P2WA1
controllers in
different bays
are sending
P2KA3
Siprotec-7SJ6xx
P2WA1
StatUrg
Positions
Positions
reports to the
P2FA1
REL 670
P2WA1
StatUrg
Interlock
Interlock
Interlock
station level
P2KA4
RED 670
P2WA1
IEDs.
PAC.SPRING.2008
Engineering
IEC 61850
48
IEC 61850
object, is the logical node instance.
From here on all DATA and attribute
names are completely semantically
defined in IEC 61850. If we look
into the functional names of figure
3 for the same control function
handled by the IED related names of
table 2, these are:
AA1E1Q3QA1CSWI.Pos
AA1E1Q3QA1XCBR.Pos
The protection related name of
the operation of distance protection
for Zone 1 is:
AA1E1Q3F1Z1PDIS.Op
All these names are completely
independent from the distribution
of logical nodes and logical devices
to IEDs, and also from the LD and
LN instance names.
A complete SCL file for a
substation automation system,
called an SCD file, includes the
functional name, the IED related
name, the communication related
(LD) name, and the relations
between them – thus serving as a
data base for translation between
the different designations for the
same LN respective DATA object.
This is shown in Figure 4 for the
above example, illustrating the
independence of the functional name
from the IED related name up to the
point where IEC 61850 provides
complete semantic standardization.
Communication engineering
IEC 61850 MMS based services
allow an interactive browsing of
the IED data model to retrieve all
communication related names. Due
to the unique LD name these can be
translated into IED related names as
well as functional names by means
of the SCD file. However, normally
operational traffic is based on
preconfigured data flow for services
allowing spontaneous sending.
These are typically:
Reporting service for status
update and time stamped events to
station level IEDs like HMI, or
gateways to network control
centres.
GOOSE real time service for
real time functions typically between
bay level IEDs, or down to process
level IEDs, e.g. interlocking related
data or protection trips and
blockings.
SMV services, if analogue
samples are needed directly from the
process, e.g. for protect ion,
synchrocheck and measurement
functions.
To evaluate the importance of
the DATA names for these services,
we have to look a bit into their
definition:
All services are configured by
means of a data set, defining the
hierarchy
Substation AA1
Voltage level E1 at 110kV



Bay Q3
Equipment QB1 : DIS
XSWI, Name /XSWI of Type m_XSWI
CSWI, Name /CSWI of Type E3_CSWI
CILO, Name /CILO of Type m_CILO
Equipment QA1 : CBR
XCBR, Name /XCBR of Type E_XCBR
CSWI, Name Q3QA1/CSWI of Type E3_CSWI
CILO, Name Q3QA1/CILO of Type m_CILO
Equipment BE5 : VTR
Function F1 : Protection
PTRC, Name /PTRC of Type E3_PTRC
PSCH, Name /PSCH of Type E3_PSCH
PTEF, Name /PTEF of Type m_PTEF
Subfunction Z1 : Distance zone 1
PDIS, Name /PDIS1 of Type E3_PDIS
Subfunction Z2 : Distance zone 2
PDIS, Name /PDIS2 of Type E3_PDIS
Subfunction Z3 : Distance zone 3
PDIS, Name /PDIS3 of Type E3_PDIS
Subfunction Z1B :
PDIS, Name /BPDIS1 of Type E3_PDIS
Function R1 : ProtRelated
RREC, Name /RREC of Type E3_RREC
RFLO, Name /RFLO of Type E_RFLO
Function M1 : Measurement
MMXU, Name /MMXU of Type E3_MMXU
2 IED related object model structure
Client association
Inter bay bus Access point
1 logical, several physical
MMS based
services allow
3 Example of a function
The server access point allows
access to data structured as
IED
interactive
follows: logical devices contain
Server
Logical Device
LN
browsing of
DO DO
the IED data
LN
DO
Logical Device
LN
DO
LN
DO
logical nodes (LN) containing
DATA respective data objects
(DO). Logical nodes on other IEDs
model.
Client associations
I/O
Process bus access point (can be same as above)
PAC.SPRING.2008
can access the data as clients
49
data to be spontaneously sent, and
a control block, defining when and
how it shall be sent, as illustrated in
Figure 6.
The reporting service only
sends the changed data values. A bit
pattern in each report identifies the
place of the data set to which the sent
data values belong.
For GOOSE and SMV services
always all values of the whole data
set are sent. The order of values in the
message corresponds to the order of
the data items in the data set
definition.
This means, that essentially
the values sent on the wire do not
contain any of the names considered
earlier, just the relation between the
sent values and their place in the data
set definition. For correct message
interpretation the receivers only
have to know, to which data set the
message belongs, and how this data
set looks like. For reports this can be
established dynamically by means
of the browsing services or data set
creation services, however also by
static configuration with a common
SCD file as base. The relation
between the online message and the
data set definition then is established
as follows:
Reports are MMS based and
MMS a ssociat ions must be
dynamically established. A report
client either builds its own data sets
dynamically (if the servers support
this), or uses preconfigured data sets.
If he relies on preconfigured data
sets, he can check at start-up the
control block revision number on
any discrepancies between static
definition and actual definition on
the IED.
GOOSE and SMV messages
work according to the subscription
principle and are permanently sent.
The message contains Ethernet level
identifications like Multicast address
and application identification
(AP P ID), and the d at a set
identification in the form <LD
name>/<LN Name>.<Data set
name>, which allows the subscribers
to identify and filter the correct
message fitting to the DATA they
want to use from their static
configuration based on the SCD file.
A control block revision number,
always sent in the message, allows
receivers to detect any discrepancies
in data set layout configuration
between sender and receivers.
This interpretation of messages
relative to a data set definition allows
to replace e.g. a GOOSE publisher
by any other IED without having to
reconfigure the receivers, as long as
the new IED.
Different physical
structures enforce
different IED related
data identifications at
IED/LD/LN level
Contains the data of the old
GOOSE message with same data
types and same semantics (functional
equivalence).
Contains or allows configuring
a data set with the same type of data
values in the same order and same
semantics related to the project as
the old IED.
Uses the same Ethernet level
addressing (Multicast address,
APPID, VLAN).
Has the same full data set name:
same LD name (if freely configurable
on the IED), same LN name (LLN0
for all GOOSE and SMV messages),
the same data set name (mostly
configurable at the IED for GOOSE
and SMV data sets), and the same
configuration revision number
(needs free setting by the tool
creating the data set, or some tool
support for the replacement).
4 Connection of functional and product related naming–example
Substation: AA1
IED: Ctrl9
Voltage level: E1
LD: LD1
Bay: Q3
Switch: QA1
of the functional identifi-
LN (class) : CSWI
LN: QA1CSWI 1
cation (left) down to the
LN class are completely
DATA: Pos
independent from the IED
Attribute: stVal
Functional name:
AA1E1Q3QA1CSWI.Pos.stVal
The structuring and naming
IED related name:
Ctrl9LD1/QA1CSWI 1.Pos.stVal
related name (right)
PAC.SPRING.2008
IEC 61850
50
Table 1 Degree of name standardization
IED structure
level
Degree of standardization
Example
designation
Stan- Predefined nadardized me semantic
Logical device LD
Syntactical (61850-7-2)
MyControlLD1
---
---
100 Kb/S
Partly: LN class (61850-7-4)
Q0CSWI3
CSWI
Switch control
200 Kb/S
Full: DATA name (61850-7-4)
Pos
Pos
Switch position
Attribute
Full: Attribute name (61850-7-3)
stVal
stVal
Status value
Engineering
For maintenance it is recommended to choose an IED related logical device name,
structured as IED name - LD relative name
Table 2
Name differences caused by architecture
Architecture
LD Name
DATA
LN Name Name
Single bay
controller
Process bus from
bay controller to
circuit breaker
interface
Central controller
with process bus
to circuit breaker
interface
Ctr19LD1
Ctr19LD1
Q0CSWI1
Q0XCBR1
Pos
Pos
LNs located in same LD
Ctr19LD1
SWg8LD1
Q0CSWI1
QA1XCBR4
Pos
Pos
LD (IED) name at switch interface IED must
be different to name in bay controller; LN
instance names are manufacturer specific.
Ctrl11LD9 Q0CSWI1
SWg8LD1 QA1XCBR4
Pos
Pos
Free LD naming would allow using centrally
the same LD names as de-centrally – if the
central LD structure is the same.
This means that the replacing IED has
beneath the requirements on compatible
semantics and data types to fulfil some
engineering related requirements, which
are not mandatory according to IEC 61850.
Further it should be considered that errors
at the reconfiguration of the data set when
keeping the old revision number and data
set identification can be safety critical,
because the receivers do not demand to be
newly configured. So, a good tool support
or testing in a simulated environment is
recommended.
Remark
The problem of binding GOOSE or
SMV receivers to the data set layout does
not appear for reporting clients, because
they can perform this binding dynamically.
However, if the names have changed,
the binding to the functional semantics,
especially binding of LN instances to
instances of switch yard equipment and
functions, is still a problem. One means
to solve this binding to the application
function is to re-establishing the link
between functional names and IED related
names also for the new IED(s). This is
Use functional
names as a key
between old
and new
configurations
supported in IEC 61850 better than
in other protocols in so far, as this
binding is done on the level of logical
nodes instead of signals, and will in
all cases, where application specific
LNs are used (e.g. no GAPC and no
GGIO), reduce to a selection of LN
instances with the same LN class,
thus minimizing the amount of
work as well as that of errors.
For good implementations of
station level clients, which internally
work with the functional names as
defined above, it is then sufficient
to reload them at driver level with
the SCD file resulting from this
re-mapping of LN instances.
Even better client
implementations allow to do
this reload per IED e.g. when
communication with the (new)
IED is (re-) established. In any case,
the probability of errors is restricted
to the remapped IED, and this
5 Different architectures
IEC 61850 offers solutions to
Ctrl 1
Ctrl 9
Station level
minimize the influence of maintenance activities at application
Ctrl 9
Bay level
level, by introducing in parallel
to the IED related identification
Swg 8
Bay controller
PAC.SPRING.2008
SWg 9
Bay controller
+ Process bus
Swg 8
SWg 9
Central controller
+ Process bus
Process level
a function oriented identification of data according to the
concepts of IEC 61346.
51
probability is quite low, because
the remapping is performed on the
relatively high level of LN instances,
supported in most cases by the
needed LN class. It should however
be considered that the new IED
should contain at least the same
DATA per remapped LN instance as
needed by the application.
Impact on engineering and
used products
The follow ing point s are
important to minimize the efforts in
case of SA system retrofit:
Use functional naming for
system engineering and the IED
related names, so that the SCD file
provides a translation between them
in a standardized format.
Use functional naming at
application level, i.e. within
application functions. Let the (MMS
based) communication drivers
translate the IED names into
functional names by means of SCD
file(s). In case of (station level) clients
which do not support this, use a tool
to create the new configuration from
the SCD file, by using the functional
name as common key between old
and new configuration.
The safety of this approach can
be supported by a system tool which
supports the IED replacement at the
functional structure on LN level,
with a check of the same respective
correct LN classes.
As we have seen, the replacement
of GOOSE servers without having
to reconfigure all GOOSE receivers
needs some optional features from
the IED respective its tool:
Support free LD naming
Support free data set naming, at
least for GOOSE and SMV data sets
Support free (guided) setting of
GOOSE confRev
To make this procedure safer,
the tool should support remapping
the new IED to the functional
names and, after this remapping,
automatically (re-)create the GOOSE
/ SMV data sets with identical layout
and name, set the LD name property
identical and take over all ‘old’
addresses.
Unfortunately, all these features
do not help for the GOOSE / SMV
case, if a changed architecture leads
to another logical device structure,
so that the requirement on
uniqueness of the LD name forbids
the proposed LD renaming, or if
due to a new physical structure the
GOOSE messages have to be split
onto different IEDs.
Some impact on system
modelling principles
A relatively safe tool-supported
binding of the LN instances of the
new IED to the functional names
by using the old IED’s binding as
template is only assured, if GGIO
and GAPC LN classes are avoided
as far as possible. This is also in the
sense of IEC 61850, which demands
using a fitting LN class wherever
one is defined. Here also some
improvements of manufacturer
IED tools might help, which
allow replacing a GGIO by a more
appropriate LN class at IED (pre-)
engineering time.
However, if the old structuring
into logical devices does not fit
to the new structuring, this does
not help. Therefore, already at the
initial system design, the logical
device structure in relation to the
used GOOSE and SMV messages
should be set up to support the
most distributed structure which
is intended to be used during the
switch yard life time. Further,
GOOSE and SMV data sets should
not reference data outside the LD in
which they are defined – else these
may later reside on different IEDs,
and therefore force a redefinition
of the data sets with appropriate
re-engineering of the receivers.
The general concept of a maximal
distributed system, even if it is
implemented centrally, also helps
in having a common behaviour of
distributed and central systems
concerning functionally connected
logical nodes, because it makes the
functional behaviour independent
from the fact if internal functional
connections between the LN
implementation are used or external
Designing systems
for the maximal
ever intended
physical distribution,
eases future
retrofit
explicit communication connections.
This has also been considered at the
more detailed definitions of IEC
61850 Edition 2 for the influence
of the test and block quality of
incoming signals, and should also be
used when implementing test and
block modes on internally connected
logical nodes.
If these additional system
structuring rules are considered,
then the consequent usage of
functional naming for application
related functions in parallel to the
usage of product related naming for
automation system maintenance, as
foreseen in IEC61850-6, supports
easy retrofit and system extension
with minimum engineering,
modification and (re-)testing effort
even if the underlying physical
architecture is changed or IEDs
of a different type or a different
manufacturer are used.
6 Communication model
GOOSE or Report messages
defined by data sets and control blocks (CB)
IED
Communi-
s
ger
trig
CB
Data
Set
Logical Device
LN
cation model
with data sets
and control
Logical Device
LN
LN
DO
DO
DO
PAC.SPRING.2008
blocks
Iana A. Apostolova J.D.
Legal Issues
53
Class Action Lawsuits
Possible
Legal
Concerns
A class act ion lawsuit is a
procedural device that permits the
litigation of multiple claims in a single
proceeding.
larger group.” Black’s Law Dictio­
nary, 7th Edition. Federal proce­
dure has several requirements for
maintaining a class action: (1) the
class must be so large that indivi­
dual suits would be impracticable,
(2) there must be legal or factual
questions common to the class, (3)
the claims or defenses of the repre­
sentative parties must be typical of
the class, and (4) the re­presentative
parties must adequately protect the
interests of the class.
As we will consistently reestablish
in these editorials, there are many
legal concerns which do, and will
continue to, have an increasingly
significant impact on the protec­
tion and control world. This issue
however, focuses on the manner
in which these legal matters are
brought to the forefront, the most
considerable of which, is the class
action lawsuit.
Whenever a blackout or other ma­
jor power disturbance occurs, mil­
lions of consumers are affected, to
varying levels on “inconvenience.”
While an individual consumer
may loose the ability to complete
his midterm paper, to a hospital,
an outage of even a couple of hours
can have devastating consequen­
ces. Clearly, in such circumstances
large institutions and corporation
possess the legal resources neces­
sary to assert their legal rights,
and demand answers and more
importantly, compensation, from
the relevant utility that they deem
at fault. However it is unlikely
that too many average consumers,
would regard themselves irked
enough to file an individual claim
versus a large, and well legally pro­
tected utility. At least so would be
the case, if not for the powerful le­
gal tool of the class action lawsuit.
In the words of the U.S. Supreme
Court, “the class action was an
invention of equity… mothered
by the practical necessity of pro­
viding a procedural device so that
mere numbers would not disable
large groups of individuals, united
in interest, from enforcing their
equitable rights nor grant them
immunity from their equitable
wrongs. Montgomery Ward & Co.
v. Langer, 168 F.2d 182, 187 (8th
Cir. 1948). It is this “procedural
device” that gives all consumers,
large and small alike, the ability to
bind together, and wage their own
personal battle, for accountability
and reparations.
A class action lawsuit is literally
defined as “a lawsuit in which a
single person or a small group of
people represents the interests of a
This definition sheds light on the
fact that the class action lawsuit
has become so popular in recent
years with power consumers. It
is evident that it would be im­
practicable for such a multitude of
customers to file individual suits,
when there are so many common
questions of both law and fact at
the core of their grievance.
The increasing phenomenon of
the class action lawsuit should be a
source of notable concern for utili­
ties, for it affords all its individual
members the ability to pool their
strength and assets together into a
lawsuit, which once resolved,
could require the affected utility to
pay compensations worth mil­
lions, versus the comparatively
modest number which an indivi­
dual suit would produce.
PAC.SPRING.2008
Biography
Iana graduated
from UCLA in
2001 with a
major in Political
Science. In 2005
she was awarded
the degree of
Juris Doctor,
from Loyolla Law
School.
During her
studies, Iana
worked for Soft
Power Int., where
she became well
aquainted with
the engineering
world. She
furthered
her business
knowledge
working for
Insurance
Marketing Inc.
Upon graduating
from Law School,
Iana joined the
Criminal Defence
field, where she
has devoted her
talents to fight
for her clients.
Iana is currently
working on her
MBA from Ashford
University.
Biographical Sketch
by Demetrios Tziouvaras, Schweitzer Engineering Laboratories, Inc.,USA
EMTP Applications
FOR POWER SYSTEM PROTECTION
The EMTP can supplement
conventional fault studies and
hand calculations to improve the
understanding of power system
phenomena and to assist in
proper protection applications.
A protection engineer may
determine extreme conditions
of steady state fundamental
frequency unbalances or
harmonic distortion that will be
faced by a protection system.
PAC.SPRING.2008
1 Comparison
Comparison of a laboratory and an EMTP simulated CT saturation test
80
80
60
60
40
40
Current [A]
STEADY-STATE APPLICATIONS
Power system operations can
cause unbalanced currents and
voltages in the network that could
impact the operation of protective
relays, e.g., during a single-phase
trip, unequal gap flashover of series
capacitors, or when a three-phase
transformer bank consists of different
single-phase units. These operating
conditions cannot be analyzed using
conventional load-flow programs
but can be easily studied using
steady-state EMTP simulations and
demonstrate the benefits of applying
EMTP for power system protection
applications.
Conventional short-circuit
and load-flow programs assume
Current [A]
Sysrem Analysis
EMTP
54
Demetrios Tziouvaras was born in Monahiti, Grevena, Greece. He holds a Masters
Degree in Electrical Engineering from
Santa Clara University, California, USA.
From 1980 to 1998 he worked for Pacific
Gas and Electric Co., where he held
various positions in the System Protection
Department including Principal Protection Engineer responsible for protection
design standards, application of new
technologies, substation automation,
relay settings, and analysis of relay operations and system disturbances. He joined
the Research Engineering Department
of Schweitzer Engineering Laboratories,
Inc. in 1998 where he is involved in digital
relay algorithm development and electromagnetic transient simulations.
Mr. Tziouvaras is a senior IEEE member and
member of the Power System Relaying
Committee. He is a member of CIGRE
and the convenor of CIGRE SC B5.15 on
“Modern Distance Protection Functions
and Applications.”
He is the author of more than 35 IEEE
and Protective Relay Conference papers,
holds three patents in the area of power
system protection and has more pending.
He has taught seminars in Protective Relaying, Digital Relaying, and EMTP at the
University of Illinois at Urbana-Champaign,
the California Polytechnic Institute in San
Luis Obispo, IEEE PES, and elsewhere. He
served as the chairman of an IEEE PSRC
working group that developed an IEEE PES
tutorial on “EMTP Applications to Power
System Protection”
20
20
00
-20
-20
-40
-40
-60
-60
-80
-80
0
25
I
25
50
I
50
75
I
75
Time [ms]
Time (ms)
100
I
100
55
a balanced power system. The
assumption of a balanced system
is usually adequate under normal
operating conditions. In cases where
network unbalances exist under
normal conditions, conventional
programs may not be able to
determine the magnitude of normal
unbalances. EMTP steady-state
solutions are performed in the
phase domain, not using sequence
components, thereby easily solving
networks with nonsymmetrical
phase impedances. The EMTP
steady-state solution may be used
to help quantify the extent of
normal unbalances to assist in relay
applications.
Open conductors create series
unbalances that are not normal
conditions, and relays may be
expected to protect against them.
However, the resulting system
unbalances may be significantly
less than unbalances resulting from
short circuits. In fact, the unbalance
currents and voltages are heavily
dependent on the magnitude of
load currents. EMTP steady-state
solutions can readily determine
voltages and current measured by
relays under such conditions. Cases
of interest are: single-phase tripping;
1 phase of a disconnect switch open.
Series capacitor gap flashing
during a fault is a special case of a
multiple unbalance. Unbalanced gap
flashover may occur as a result of a
short circuit, or unbalanced bypass
may occur as a result of control or
bypass equipment problems. EMTP
can calculate steady-state unbalance
currents and voltages resulting
from such unbalanced operation.
Knowledge of these quantities
can assist in proper protective
relay application and settings.
Simultaneous or cross-country
faults are difficult to analyze with
conventional short-circuit programs
that use sequence components for
analysis but are easily handled by
EMTP simulations.
Under some condit ions ,
unbalances are deliber ately
introduced into a network to address
special problems. For example, failure
of a large single-phase transformer
may necessitate its replacement with
another single-phase transformer
having different MVA capability
and different leakage reactances.
EMTP simulations can be used in
such a situation to determine the
steady-state unbalances resulting
from load flowing through the
unbalanced transformer impedances.
The simulations would reveal the
EMTP is a valuable tool
for analyzing
the transient and
dynamic behavior of
power systems.
level of system unbalance and the
circulating current in the transformer
bank tertiary winding. Relay
engineers can use the results of the
EMTP steady-state simulations to
determine the effect on transmission
line protection and the required
settings for transformer tertiary
overload protection.
In addition to unbalanced
analysis, steady-st ate EM T P
solutions help to study the effect
of non-fundamental frequencies
on relays. For instance, the system
response at a variety of frequencies
generated by a multifrequency
injection may be used to test for the
presence of system resonances. Such
information will help determine the
importance of harmonic rejection
in relays in particular applications.
2 Calculated distance values
Calculated distance m values with normal and saturated currents
1
The calculated distance to the fault m
value corresponding to a normal fault
0.75
Saturated
Saturated
current settles to 0.33 as expected. For
a saturated phase current (Fig. 2), the
2.5
0.5
Calculated m
Calculated m
5
0
calculated distance m value crosses the
-2.5
0.25
unity line with a half-cycle delay and
Nonsaturated
Nonsaturated
-5
0
0
0
0.05
I
0. 05
0.1
I
0.1
0.15
I
Time (s)
0.15
0.2
I
0.2
settles around 0.45 because the current
Time (s)
0.25
I
0.25
remains
0.3 in a saturated state.
PAC.SPRING.2008
Sysrem Analysis
EMTP
56
Effectively
using EMTP to
model complex
power system
operating
conditions can
improve the
protection
schemes
and provide
answers
to relay
operations
that otherwise
are difficult to
obtain.
Power line carrier frequencies
propagate in several modes on a
multiphase transmission system.
Study of these propagation modes
is complicated by discontinuities
in the transmission circuit, such as
transpositions and overhead-tounderground interfaces. At high
frequencies, such as those of power
line carrier, EMTP steady-state
solutions can be used to study
the effects of line transpositions
and discontinuities on wave
propagation.
Transient Applications
Several transient applications
are discussed here to demonstrate
the benefits of EMTP applications
in the field of system protection
engineering.
EMTP is a very powerful tool in
the study of transient conditions.
EM T P aids signific antly in
protective relay applications since
protective relays operate during
transient conditions. Traditional
relay application has considered
fault conditions to be temporary
steady-st ate condit ions that
can be studied by fundamental
frequenc y steady-st ate fault
studies. Conventional short-circuit
studies exclude some important
phenomena, and some conditions
are not even caused by short circuits.
Additionally, the duration of a
transient EMTP study is variable.
The period of signals of interest may
vary from microseconds to tens of
seconds.
Series capacitors in transmission
lines often present challenges to
protection systems. Depending on
the size and location of the capacitor
bank and the overvoltage protective
equipment such as spark gaps or
metal oxide varistors (MOVs), the
operating and polarizing signals
presented to transmission line
protection can be very unusual.
C o nve n t i o n a l s h o r t- c i rc u i t
programs often have difficulty in
calculating fault quantities because
of the non-linear performance of
the series capacitor overvoltage
protection gaps or MOVs. Further,
PAC.SPRING.2008
the interaction of the series
capacitors and power system
introduce off-nominal frequencies
that can affect protective relays.
When the capacitor is switched
into or out of the transmission line,
system oscillations arise that should
be considered for line protection
application and setting.
Relay response to evolving faults
is sometimes uncertain. This is
especially applicable to protection
systems, which must determine
the type of fault before measuring
the faulted loop impedance (such
as switched distance protection
schemes). The uncertainty arises
because of the wide variety of
rapidly changing conditions that
may potentially confuse a protection
system, which is trying to determine
the type of fault. EMTP provides
a convenient way to generate test
signals to physically test a relay's
response to such faults.
Traveling wave high-speed
transmission line protection
systems do not use the fundamental
frequency components. They
use higher frequency signals to
determine the direction or type of
fault. EMTP-generated signals are
essential for application studies,
testing and settings of such relays.
Some power system effects
simply cannot be investigated by
any other means than a transient
analysis program. Single-phase
switching is one area where EMTP
has been widely applied. An
important problem in such cases
is extinction of the secondary arc
after the faulted phase is opened at
the line terminals. This secondary
arc may be maintained by capacitive
and inductive coupling with
adjacent energized phases. Special
four-reactor bank applications have
been designed and widely applied to
minimize the duration of secondary
arc. The presence of these reactors
and the secondary arc can have
significant effects on transmission
line relaying. EMTP has been used to
study the secondary arc extinction
characteristics and protective relay
response to such transients. To
perform single-phase tripping,
transmission line protection relays
are required to determine the
faulted phase. Numerous faulted
phase selection schemes have been
designed. The effect of heavy load
and possible high fault resistance
during single line-to-ground faults
remain challenging applications.
EMTP has been widely used to test
relay response to such challenges.
High-speed automatic reclosing
is frequently applied to maintain the
integrity of a transmission system
after a short circuit. Voltage detectors
are sometimes used to supervise such
reclosing to ensure the remote line
terminal has opened before reclosing
occurs. The oscillatory decay of the
trapped charge remaining on the
line may cause problems to voltage
detectors used for such supervision.
EMTP offers a convenient way to
test voltage detector’s response to
such oscillatory decay. The dynamic
response of the power system to
faults and automatic reclosing
has an important effect on relay
performance. This is particularly
important on protection systems
designed to trip or block on OOS
conditions or to respond to rate
of change of certain parameters.
EMTP may be used to simulate such
conditions to determine protection
performance.
The time varying response of
rotating machines to changes in
system conditions has always caused
difficulties in protection application.
Induction motors can contribute
current to short circuits for a brief
time, but such contributions are
normally neglected in protection
applications. Synchronous motors
and generators cont r ibute a
varying amount of current to short
circuits, depending on the type of
Effectively using EMTP
can provide answers to
relay operations.
57
Protection engineers are
encouraged to apply the various
4a CVT Transients - wave
CVT transients reduce the fundamental voltage magnitude
capabilities of EMTP to help
them design more robust and
60
60
CVT
Transient
CVT
Transient
40
40
dependable power systems.
Figure 4 a/b:
shows a CVT
transient response
during a line-toground fault.
Wave
0
0
–20
-20
Ratio
Voltage
Ratio
Voltage
–40
-40
–60
-60
60
–1
40
10
20
Wave
-1
–0.5
0 CVT Transient
0.5
I
-0.5
I
0
80
–20
6
–40
1
1.5
I
I
0.5 Ratio Voltage
1.0
I
1.5
2
2.5
Time (cycle)
I
2.0
I
2.5
3
I
3.0
Magnitude
4b CVT Transients - magnitude
Ratio Voltage
4
–60
CVT transients reduce the fundamental voltage magnitude
2 –1
10
5
0
–1
8
2.5
Magnitude
Magnitude
excitation system and the duration
of the period of study. Protection
of synchronous motors is normally
applied considering response within
a cycle or two of the fault initiation,
or after a considerable period of time
when steady-state fault conditions
exist. This type of study leaves a
gap in simulation that is readily
covered by EMTP simulations of the
generator and its excitation system.
Synchronous machines could lose
synchronism (OOS) with the power
system, requiring prompt protective
relay action. These OOS conditions
are readily simulated by EMTP.
The results of such simulations aid
in the application of power swing
blocking, OOS tripping, or field
failure protection applications.
EM T P simulations are not
limit ed to elec t roma gnet ic
transients. EMTP can be used
to st udy elec t romechanic al
transients. For instance, large
thermal turbine-generators have
been damaged or destroyed by
electromechanical subsynchronous
oscillations caused by series
Wave
20
20
–0.5
0
0.5
1
1.5
2
2.5
3
CVT Output
–0.5
0
Ratio Voltage
Voltage
0.5 Ratio
1
1.5
2
2.5
3
Time (cycle)
06
-2.54
-52
0
Figure 4 a/b:
also shows the
fundamental
frequency mag­
nitude of a CVT
secondary voltage
as compared with
the ideal ratio
voltage.
Output
CVTCVT
Output
–1
0
–0.5
I
-0.05
0
I
0
0.5
I
0.5
1
Time (cycle)
I
1.0
1.5
2
2.5
Time (cycle)
I
1.5
I
2.0
I
2.5
3
I
3.0
3 Saturated and normal phase currents
Calculated m
Calculated m
55
Saturated
Saturated
2.5
2.5
00
Nonsaturated
Nonsaturated
-2.5
–2.5
–5
-5
Figure 3:
shows the
unsaturated and
saturated current
waveforms from
an EMTP simulation of a CT model
for a line fault at
a distance of 33
percent from the
relay location.
0
0
0.05
I
0.05
0.1
0.15
I
0.1
Time
I (s)
0.15
0.2
I
0.2
0.25
I
0.25
Time (s)
0.3
I
0.3
PAC.SPRING.2008
5 Overreach due to CVT transients
Two apparent impedance loci of an end-of-line fault, calculated from the
ideal2.5
ratio voltage and the CVT secondary voltage
2.02
Apparent
Impedance
Apparent
Impedance
From
fromRatio
Ratio
Voltage
Voltage
X-Ohm
1.5
1.5
X - Ohm
Sysrem Analysis
EMTP
58
1.01
0.5
0.5
Apparent
Impedance
Apparent
Impedance
From
CVTCVT
Output
from
Output
0
RelayProtection
Protection
Region
Relay
Region
0
-0.5
–0.5
00
0.5
0.5
1.0
1
1.5
1.5
R - Ohm
2.0
2
R-Ohm
capacitors on nearby transmission
lines. Subsynchronous electrical
oscillations can excite mechanical
resonances on large thermal
turbine generators with sometimes
c at a st rophic result s . EM T P
simulations have been used to
apply protection systems to prevent
unit damage by subsynchronous
oscillations.
Examples:
Simulation of Instrument
Transformer Transients
Current and voltage transducers
provide instrument-level signals
to protective relays. Protective
relay accuracy and performance is
directly related to the steady-state
and transient performance of the
instrument transformers. Protective
relays are designed to operate in a
shorter time period than that of the
transient disturbance during a system
fault. Large instrument transformer
transient errors may delay or prevent
relay operation. EMTP simulation of
instrument transformer transients
can be used to study their effect on
the performance of relay elements.
Simula t ion of Cur rent
Transformer Transients:
CTs can saturate due to large
symmetrical fault currents or
the prolonged presence of a DC
component in the primary fault
current. The fidelity of the CT
transformation is reasonably good
until saturation takes place. Upon
saturation, the CT current delivered
to the relays and other instruments
deviates in both magnitude and
phase angle from the current flowing
in the power system. Current
transformer transient performance
can be easily modeled by EMTP.
Transient saturation, steady-state
saturation and poor performance,
due to low-frequency effects,
(including geomagnetic induced
currents) can all be simulated.
Figure 1 shows a comparison of
recorded laboratory secondary CT
waveforms and EMTP simulated
secondary CT waveforms. The
simulation results are nearly identical
to the laboratory tests.
Figure 3 shows the current
w avefo r m s f ro m a n E M T P
simulation of a CT model for a line
fault at a distance of 33 % from the
relay location. Figure 2 shows the
response of a numerical distance
relay to the unsaturated and saturated
waveforms shown in Figure 3. The
calculated distance to the fault m
value corresponding to a normal fault
current, settles to 0.33 as expected.
For a saturated phase current
(Fig. 3), the calculated distance m
value crosses the unity line with a
half-cycle delay and settles around
0.45 because the current remains in
a saturated state.
Capacitive Voltage Transformer
(CVT) Transients:
Similar to poor CT performance,
CVTs can also cause unexpected
protection system performance.
6 EMTP simulation of out of step phenomena
the OOS condition resembles that of a two-machine system
2000
Magnitude (Mag)
Figure 6, 7:
The waveforms
shown in those
figures are from a
simulated
multi-machine
network.
0
-2000
0
PAC.SPRING.2008
500
1000
1500
Time (ms)
2000
2500
3000
59
One of the most common causes
is a subsidence transient that can
grossly distort the secondary signals
presented to a relay. (Fig.4a,b) EMTP
can simulate CVTs connected to the
power system and provide suitable
test signals for determining relay
performance. In addition to the
subsidence transient, CVT response
to non-fundamental frequency
signals can also be determined. CVT
transients reduce the fundamental
component of the fault voltage and
cause distance relays to calculate
a smaller than actual apparent
impedance to the fault. (Fig. 4 a,b)
Ferroresonance is possible in any
system composed of capacitors and
iron-core inductances. In a CVT, the
interaction of the source capacitance
with the tuning reactor inductance
and the step-down transformer
magnetizing inductance can lead to
a ferroresonance oscillation. CVT
manufacturers use ferroresonancesuppression circuits (FSCs) to
reduce or eliminate ferroresonance
conditions. EMTP can be used to
simulate ferroresonance conditions
in CVTs.
Relay Testing with EMTP
Generated Signals
Relay testing in the field has
generally involved steady-state tests
to determine the integrity of the
relay. These tests were performed in
the past using variacs, phase shifters,
and load boxes, or more recently with
modern electronic test equipment. In
recent years, more interest has arisen
in testing the relays under transient
fault conditions that they will likely
encounter while in service.
For many years, model power
systems were used for transient
tests. Because of the expense, such
systems were only available to
relay manufacturers and research
laboratories. Since digital system
analysis techniques are widely
available, EMTP or real-time digital
simulators are often the tools of
choice to generate transient test
signals for relay application tests. For
troubleshooting tests, digital fault
recorder (DFR) or relay-captured
event signals may be available to
replay using modern electronic test
equipment.
EMTP simulations are able to
represent a variety of power system
conditions in which protection
systems must operate reliably. The
simulations may include models
of the instrument transformers
used to convert the signals to
relay input levels. Since the EMTP
output consists of a file of numbers
representing instantaneous values
of signals "seen" by a protection
system, some hardware is required
to convert these numbers to an
analogue electrical signal that can
be injected into the relay. The
format of test files has recently been
standardized to simplify exchange
between interested parties. This
allows test files from actual DFR
records or EMTP simulations to be
used almost interchangeably.
EMTP is a valuable
tool for relay testing
and setting
optimization.
Test ing of Power-Swing
Protection Functions:
The most appropriate test method
to verify the relay behavior during
stable power swings or OOS (loss
of synchronism) conditions is to
generate a number of COMTRADE
test cases from EMTP simulations
and play them back into the relay
using modern test equipment.
Modern test sets are capable of
replaying COMTRADE waveforms
captured during power swings by
relays and DFRs or generated by
EMTP. Using this methodology, one
can verify if the relay will perform
satisfactorily during stable or
unstable power swings.
Figures 6 and 7 demonstrate
how different the waveforms are on
two transmission lines in the same
network during an OOS condition.
Testing of power-swing protection
functions with traditional relay
testing equipment can be very
difficult, if not impossible, to
perform. The difficulty arises from
the inability of older test sets to
reproduce the type of waveforms
present during power swings.
7 Out of step waveforms of multimachine power systems
The example shows how complex the OOS waveforms can be due to multi-machine mode excitation
Figure 7:
The waveforms
shown here
would be impossible
to generate using a
test set while trying
to ramp the voltages, currents, and/or
frequency.
Magnitude (Mag)
1000
0
-1000
Time (ms)
0
500
1000
1500
2000
2500
3000
PAC.SPRING.2008
p
mr
aa
ts
a
ad
the guru
60
60
More than
50 years in
protection.
shri
1991
1982
1998
All awards
have been
very enjoyable,
intoxicating and
encouraging.
Technical
innovation and
developments
are taking place
in a very high
pace.
PAC.SPRING.2008
2008
the guru
Biography
I like to read
and think
about all the
questions that
we have not
answered yet. .
Shri Mata Prasad
Shri Mata Prasad has more than 50
years of experience in the fields of
electric power systems protection,
extra high voltage and high voltage
DC systems, power plants and SVC.
He received his B. Sc. degree in
Electrical Engineering from BHU
Varanasi. He was responsible for
the development of the first 400 kV
system, as well as the first SVC, the
first HVDC bulk power transmission
and the first HVDC asynchronous
link in India.
He has also worked in Sweden, the
UK and France and has been an
active member of many professional
organizations, achieving the status
of Distinguished Member of CIGRE
and Senior Member of IEEE, and a
Fellow of the Indian Academy of
Engineering.
For his accomplishments and
contributions he has received
many national and international
awards, such as the CBIP Golden
Jubilee Award. the CIGRE Technical
Committee Award and the CEA
Silver Jubilee Celebrations Award.
He has authored and presented
more than 115 papers at many
conferences around the world.
PAC.SPRING.2008
62
My family
plays a very
important
PAC World: Would you tell us something about the
places where you were born and where you grew-up?
MP: I was born at Varanasi, UP on 3rd April 1932 and
completed High School (Commerce) from Sanatan Dharam
High School in 1948, Intermediate (Science) from Banaras
Hindu University 1950 and B.Sc., Electrical Engineering
from Banaras Hindu University in 1954, in Varanasi.
PAC World: Do you think there was something special
during your school years that affected your future?
MP: I was quite keen to study engineering, especially
mechanical engineering, since the day I started school due
to my special fascination for machines and mechanical
gadgets. Unfortunately, I had to continue my academic
education until high school with non-science subjects
like commerce, bookkeeping and accounting. However
this did not discourage me from pursuing an engineering
education.
PAC World: Did your family influence your career?
MP: I lost my father in 1948 just before my high school
examination. The inspirational support I received from my
creative mother gave me all the strength to complete
my engineering courses - securing first division in all the
PAC.SPRING.2008
four years of my engineering education.
I believe, it was God’s wish that none
of my close relatives came forward to
guide or support me in my efforts and
my life.
I surrendered to Almighty God to guide
me all the way. This proved to be a
blessing as I received all the help from
HIM and I never felt alone. The strength
of my mother and guidance from Above kept me fully
energized to realize my objectives.
PAC World: Did you have any special interests while in
school?
MP: I did have interest in pencil sketching, instrumental
music, drama and some games like volleyball, but my
special inclination was towards reading everything I
could lay my hands on, including novels, stories and
mythological/religious masterpieces like Ramayana,
Mahabharata and Bhagavad-Gita. The contribution and
direct influence from Shri Jaishankar Prasad, a great name
in Hindi literature who was a close friend of my father and
quite influential. I had time allotted to study my normal
course and general literature studies that did not leave me
role in
63
time for indoor or outdoor games. I always felt a shortage
of available time during my youth and even today I feel
that there isn’t enough time and so many things to do.
PAC World: How and when did you decide to study
electrical engineering?
MP: The four year engineering course at BHU consisted
of two years for combined study in civil, mechanical and
electrical engineering. In the third year, one has to select
whether to pursue a mechanical or electrical discipline.
As I said earlier, I had a blind infatuation for mechanical
engineering however a group of my Electrical Engineering
professors, especially Prof PC Dutt, Prof MC Pandey and
Principal M Sengupta advised me to choose electrical
engineering as they felt that I was more suited for it.
Today I must admit that my professors correctly judged
my aptitude and I owe everything to them.
PAC World: Did you study protection while in
university?
MP: Yes, I did study basics of Protection relaying covering
Generator, Transformer and Transmission Lines and this
particular topic fascinated me especially when I had gone
through some of the classic relaying schemes described by
Lewis and Tippet, Montieth and others published in AIEEE
Transactions . I was later exposed to protection philosophy
when I joined active service in UP Electricity Department
in 1957.
PAC World: Did you have any other interests while
studying? Sports? Music? Arts?
MP: As I said earlier, I did have great interest in music
and arts but I could never fulfill my desire to accomplish
anything further in this regard. I was very good in pencil
sketching of portraits and landscapes. I should have continued in these fields at least after retirement!
PAC World: Where did you start your career? Did you
work on power system protection from the beginning?
MP: From October 1954 to January 1955 I was under
training in Rihand Hydro project department and then
shifted to field duties - responsible for surveying and
construction of 33 kV double circuit lines. After joining
the Electricity Department as Assistant Project Engineer
in 1957, the first technical job allotted to me was to
study the Protection System for Rihand Power Plant and
draw specifications for protection of 132 kV lines and
substations. Thus, I started my career with Protection and
that became my first love.
PAC World: Would you describe the most challenging
project that you have been involved in?
MP: There were scores of challenging jobs entrusted
to me and successfully delivered. For example, the
interconnection system of the Obra 1000 MW power plant
with nine 400 kV lines of length varying from 140 to 400
km. In 1984, I joined NTPC on deputation for the HVDC
Projects and also for handling the associated 400 kV lines
from power plants and interconnected network. I had the
privilege to be actively associated with the first 400 kV
Static Var Compensators at Kanpur, the first 2*250 MW
Asynchronous Back-to-Back HVDC Link between Northern
and Western Regions, the first 810 KM Long +/- 500 kV
Bulk Power HVDC Transmission from the Rihand Power
plant to the Dadri HVDC Receiving Station.
PAC World: You received several awards for science and
technology in your country. Would you describe some
of them and why you did receive them?
MP: God was very kind to me that I received the following
prestigious awards:
CBIP Golden Jubilee award in 1982 for my contribution
for successful execution of field tests on 400 KV system
NPSC Award in 1991 for Excellence in Power System
Management
“Distinguished Member” of CIGRE (France) Award in
1996 for my contribution in CIGRE Activities in India and
abroad
CIGRE Technical Committee Award in 1997 for
Outstanding Contribution in SC 14 HVDC & Power
Electronics
Scroll of Honour from Institution Of Engineers (I)
Calcutta in 1997 as Eminent Engineer
Fellowship of Indian National Academy of Engineering in
1998
CEA Silver Jubilee Celebrations Award for Excellence in
Design and Engineering of Power Sector in 2000
Life Time Achievement Award by IEEEMA in 2008 for my
contribution on Switchgear and Control Industry in India.
PAC World: Which of your awards you consider the
most important and why?
MP: All of the awards are important to me but the following three awards are most precious to me: CBIP Golden
Jubilee Award in 1983; Silver Jubilee Celebrations Award
PAC.SPRING.2008
Shri Mata Prasad
the guru
64
I hope the full
IEC 61850 will
be applicable and
of CEA in 2000; and the Life Time
the design and
Achievement Award in 2008 from
IEEMA.
testing engineers
PAC World: How did you feel when
will be trained to
you received these awards?
MP: Oh! How do I express it?
Very enjoyable, intoxicating and handle all such
encouraging!
applications.
PAC World: What do you consider
your greatest achievement?
MP: Optimizing the design of EHV
Network and appreciation of impact
of Reactive Power Compensation in Indian Power Network
affecting the Security, Reliability and Efficiency of the
network.
PAC World: And what do you consider your greatest
personal achievement?
MP: Motivating and providing training to young engineers
to enrich themselves with the latest technology and bring
the country to a level even with any developed country.
PAC World: When and how did you get involved in
CIGRE activities?
MP: My association with CIGRE started when I was with
CEGB Bristol. Dr. John Rushton and Mr. L Annanin of Plant
Design Department of CEGB had virtually indoctrinated
me with CIGRE philosophy.
PAC World: How did you share your knowledge and
experience? Did you write papers or books, or did you
teach directly to your younger colleagues?
MP: I believe that technical knowledge acquired must be
distributed to younger engineers in order to motivate and
inspire them to rise further in their profession through the
PAC.SPRING.2008
use of acquired technology. There is an old saying that
every word is a Mantra, every plant and herb is a medicine
and no man can be deemed as unfit. What is scarce is the
teacher, with spirit and desire to teach and pass along
knowledge.
I have not written any books on my preferred subjects
but have contributed more than 115 technical papers to
various national and international conferences in various
countries: North and South Americas, Europe, Australia,
China, etc. I have had extensive discussions with the de­
legates from utilities and private sector industries and I am
satisfied that my papers have created interest.
PAC World: Do you still participate in conferences? Do
you still present papers?
MP: Yes, I do, but my contributions have reduced and that
is quite natural. I am also promoting and supporting the
need for experienced young engineers to come forward
and take part in international and national conferences.
PAC World: What do you think about the difference in
the technology that we use for protection today and
when you started?
MP: There is a marked difference due to the onset of solidstate electronics and now the digital techniques. However,
the philosophy remains the same. The fantastic journey
from four-pole induction cup relays with polarization from
healthy or faulty phases to the use of replica impedance
using phase or amplitude comparators has been quite
rewarding to study and apply.
The complex multi-level digital electronics have made the
protection relaying much more versatile with multiple be­
nefits. The era of Computer relaying has now arrived; Phasor and wide-area measurements with GPS appear to be
65
We need to think
more about what
we can do with
our abilities
quite complex and dynamic. The relays seem to transform
into a universal type of protection and measurements fully
fitting into SCADA and remote integration. “One Substation and One Computer” as a part of a complete SCADA
and Substation Automation appears to be the real target.
PAC World: What is the difference in the workplace
between when you started work and today?
MP: The difference is too great to describe. For some time
now we have wondered how the whole protection application, testing and coordination were done in olden days
completely on a manual basis; the application gave us very
good insight. We are now required to handle the black-box
with computer assisted testing. However, the present day
technique is versatile and efficient.
PAC World: What do you think of the impact of IEC
61850 on the future of protection?
MP: How much did we struggle to coordinate the systems
provided by different manufacturers for SCADA Load
dispatch and integrating various control functions of
various equipment? Now with one common platform
the coordination becomes very smooth and rewarding. I
hope within a couple of years the full IEC 61850 would be
applicable and the design and testing engineers would be
trained to handle all such applications.
PAC World: What is your definition of retirement?
MP: For me the word retirement does not exist. You may
be working in one arena and stage and after exiting your
role, you go to other areas. The superannuation at the
age of 60 is just a milestone to be celebrated to take off
to next stage of working with renewed spirit with new
tires on the wheel. I cannot forget the spirit of Dr. Charles
Concordia whom I had met several times during CIGRE
Conferences in Paris where he used to come every two
years. He had grown weak with a frail body but he still had
a strong will to learn and teach. Now he is no more - at the
ripe age of 93.
PAC World: What do you think about the Internet?
MP: Internet has revolutionized the entire world and
equally well the Power System in all the fields. You can
realize your dreams through integration of computer,
power electronics and Internet. The Internet has become
very addictive.
PAC World: What books do you like to read?
MP: I have an insatiable hunger for purchasing books of all
kinds including English and Hindi covering Fiction, History
and Region besides technical Handbooks and Classics and
above all International Conference Publications. I am a
very fast reader. I study different books and like to share
with my colleagues in CEA, PGCIL and NTPC who show
interests and believe in imparting and exchange of such
knowledge.
PAC World: What do you like to eat?
MP: I am strictly vegetarian, as I believe our human body is
designed for only such foods. I like spicy foods and mostly
drink tea – for example Darjeeling tea mixed with some
Tulsi leaves that I add to it.
PAC World: What music do you usually listen to?
MP: I like to listen to instrumental classics from known
maestros especially those who play sitar, flute shehnai and
percussion instruments. My interest in light music, Gazals
and good songs from films is always kept alive. When I was
younger I was very fond of films - both English and Hindi and I was a regular visitor to cinema halls. Of late, this has
reduced and I prefer watching the good ones on my TV
through a DVD player. I have my own collection of film and
music CD's
AC World: How do you spend your time when you are
not working?
MP: When I am not working, I remain at home. I like to
read and think about all the questions that we have not
answered – where do we come from, are there any other
civilizations out there and many others. If we look at
Stephen Hawkins and what he has achieved despite his
disability – we need to think more about what we all can
do with our abilities. I also visit friends for a chat. I wish to
provide more time to my family as I had deprived them of
the same when I was working full steam.
PAC World: What do you think are the biggest challenges for our industry?
MP: Technical innovation and new developments are taking place at a very fast pace and one must plan to with-
PAC.SPRING.2008
Shri Mata Prasad
the guru
66
The secret of being together is very simple - my
wife loves me and believes in me and I do the
same.
stand the impact of such a fast pace through deployment,
structured training and modernizing the course contents
in degree and post degree classes to create more avenues
in Power System Engineering education.
The way the young engineers of any discipline are being
pushed blindly towards IT must be handled discreetly.
Complete fusion of power electronics, information technology and computer application with special reference
to Power System Engineering must be examined by the
technical institutes.
PAC World: What do you think about the interest of
young engineers in power systems protection?
MP: Young engineers are like plastic clay and one can mold
them into any shape. They are swayed by the winds of
explosive development in electronics and feel that this is
their final goal. This misty notion has to be intelligently
clarified. These days young engineers feel that protection
relaying is too complicated, forgetting however that in
their own application and relaying, the algorithms are common and very easy to understand.
PAC World: You were married in 1954. What is the
secret of being together for so many years?
MP: IIt is very simple. My wife loves me and believes in me
and I do the same.
PAC World: If you were standing in front of an audience
of young engineers, what would you tell them?
PAC.SPRING.2008
MP: The whole universe is based on electrons and neurons.
Power system engineering is one discipline that throws
the real challenge. It is a different path and power system
engineers become rather introvert, just as they have to
think and act. However, the challenges that come up in
delivering the objectives of the system engineering and
protection is really intoxicating and once you have fallen
in love, you will remain faithful forever. I always give an example of doctors and lawyers who have to study on a daily
basis, consult the latest developments in their profession
and then they achieve their goal of eminence. This is true
for power system engineers, as they will always have to
keep themselves fully aware of the developments through
regular study and interaction.
PAC World: How do you think we can attract younger
engineers to our field?
MP: By providing a better working atmosphere with all the
necessary tools, better training and prompting them to
participate in interactive conferences for exposure to the
latest technology.
Good technical documentation with immediate access
for references, when required.
Recognition of their talent, experience and occasional
pat on their back.
Better payment as specialists, corresponding to their
expertise and contribution.
A Very Close Look
continued on page 8
GALLERY
Digital Art by Harmeet Kang
A slightly colorful look
at signal processing
inside a relay
Harmeet Kang
UK
Harmeet is a
protection design engineer
at AREVA T&D
Automation, Stafford, UK
who believes that
protection is not just
science, but
art as well
PAC.SPRING.2008
PAC.SPRING.2008
PAC history
70
Distance Relay R1 Z23bg
History is the tutor of life
Distance protection became the
most important protection techno­
logy in the twentieth century.
by Walter Schossig
Protection
71
This article discussees the next phase in distance protection development
History
Biography
Distance
Protection
From Protection Relays to Multifunctional
From continuous to multi-zone characteristics
First publications and first relays for distance protection
were covered in the last issue. The requirement of the
utilities was a decrease of the tripping time to a value less
than 2 s. To achieve this they skipped the distance-to-fault
depending continuous tripping characteristic and changed to
cascaded (multi-step) or mixed characteristics. The distance
relays provided by BBC and Siemens in 1928 still used the
continuous characteristic. Stoecklin J. proposed and BBC
developed a Relay that used the crossed-coil-ohmmeter
(known from measuring devices). It was patented for selective
protection. The base time of this relay was 0.5 to 1 second,
which increases with the distance to the fault up to five second.
The device consisted of three mechanically united main parts.
The impedance startup started a timing mechanism, while
an ohmmeter limited the relay’s time. The timing element
-clockwork with manual winding - measured the time and
operated exactly. It disburdens the current system; the result
was a well working device with small power consumption,
even with low currents. The clockwork stored approximately
100 seconds operating time - equal to 50 operations of the
device. Only after this, a manual raise was necessary - an issue
that was welcomed by operating staff at this time because
it requires a systematic check of the relays. The Ohmmeter
functioned as the directional element as well, eliminating
the need for special reverse-power relays. A flag showed an
operation of the relay and a slave pointer the distance of the
fault. For resetting, a winding up of the clock up to a stop
position was necessary- pointer and clock came back into
normal position.
Impedance protection of Siemens was put into operation
with the 50-kV-ring Bleicherode-Huepstedt-MuehlhausenLangensalza (Germany) in 1929 . (Figure 6). In the same
year distance protection was used for the first time in the
28-kV-grid of Vienna (Austria). To prevent out-of-step
of generators and motors, a change from continuous to
multi-step time characteristics was observed in the next 10
years. A fast tripping time of less than 0,3 s was achieved with
balance beam electromechanical elements. Therefore, these
relays had their own name - "fast distance protection".
At the same time "express impedance relays" for use in
medium voltage grids were developed. Their advantage was
PAC.SPRING.2008
Walter Schossig
(VDE) was born
in Arnsdorf (now
Czech Republic) in
1941. He studied
electrical engineering in Zittau
(Germany), and
joined a utility in
the former Eastern
Germany. After the
German reunion
the utility was
renamed as TEAG,
now E.ON Thueringer Energie AG in
Erfurt. There he received his Masters
degree and worked as a protection
engineer until his
retirement. He was
a member of many
study groups and
associations. He is
an active member
of the working
group “Medium
Voltage Relaying”
at the German
VDE. He is the
author of several
papers, guidelines
and the book
“Netzschutztechnik (Power System
Protection)”He
works on a
chronicle about
the history of
electricity supply,
with emphasis on
protection and
control.
the use of a step time characteristics (Figure 3). They were able
to protect 70% of the length of line with an operating time
of 0,3 s . Neugebauer,H. and Geise,Fr., Siemens, proposed
an express impedance relay in 1932. It was the first distance
relay in an economical single plate housing per end of line. Fast
distance relays were used to achieve short tripping times in
the EHV-grid (solid earthed star point). Usually they had three
measuring elements (in the English-speaking countries up to
six). Single-pole autorecloser with definite 3-phase trip was
possible now.
In the medium voltage, the grids had an isolated star point.
Petersen,W. invented the earth-fault neutralization in 1917.
Since then, especially in the German-speaking countries,
compensated grids are quite common. The capacitive earth
fault current is compensated by the inductive current and
continuing operation of the grid is possible. Fast distance relays
with only one measuring element were sufficient to detect 2and 3-phase short circuit faults.
The distance protection in Europe was the most often
used protection technology on mashed or parallel-operated
high voltage grids. When the short-circuit power in the grid
became higher, the requirement for fast tripping on the whole
line length became important. Ackermann already showed
a proposal for a step protection in 1920/21. This was used
in Siemens reactance relays in 1930, in the Oerlikon-Mini­
mum-Impedance-Protection and the newer distance relays of
Westinghouse Co. and General Electric Co.
AEG developed their first fast distance relay in 1934 (SD1).
It uses pure three-step characteristics; fast tripping times of 0.3
up to 0.4 s were achieved. As an under-impedance protection
it uses two balanced beams, which were set up to different
lengths of the line. Additionally it consists of a 3-step timing
element and an iron-cored dynamometer as a directional
element. Startup was realized with built-in overcurrent
elements or - in a separate housing - with under-impedance
elements. The right housing consists of measuring elements
and the directional element with a tapped voltage-matching
transformer (for impedance setup). The other two devices
contained the startup, the choice of measuring values and
the three-step timing relay. For the detection of two-phase to
earth fault the SD1 used for the first time the sum current and
a change to the phase-earth voltage for the measurement of the
impedance. The one-system protection relay required the right
choice of measured values. Special auxiliary relays, with strong
contacts were necessary. The SD1 was already equipped with
HF-channel to realize a directional comparison protection. For
the medium voltage, the less complex SD2 was provided.
The Arrival of Rectifier Technology
In 1937 AEG presented as a first big vendor the use of
metal rectifiers in a distance relay with their SD4. Since then,
it was possible to reduce the measurement of the short-circuit
loop to a DC-measurement. Influenced by voltage and current,
a rectifier operates sensitive plunger coil relays. The power
consumption in the voltage circuit could be decreased ten
times - in the medium voltage it was possible now to supply
several distance relays with one busbar-voltage-transformer.
After the good experiences with rectifier technology in
Germany, a bridge connected rectifier was common at the end
of World War II. Two or three sets of rectifiers supply relays
with one moving coil (Figure 7). Voltages and currents were
provided with interposing transformers to the Graetz-Circuit.
A polarized moving coil relay was in the shunt arm of the
anti-parallel switched rectifiers. It closed the contacts at a
certain ratio of voltage and current.
Due to the very low power consumption of the rectifier
measuring systems it was not necessary to rectify the whole
transformer current - only a current proportional voltage
over a diverter resistor was necessary. In the first AEG SD4
relays (1934) this resistor was connected via a phase selection
contact to the affected current circuit.
The selection transfer, developed in the last two years
of World War II the resistance was realized as a 3-pole one.
in relays with doubled earth fault detection as 4-pole. The
secondary circuits of the current transformer in that case
did not need to be switched. The selection of current was
realized with normal contacts. In that case in the current as
in the voltage a correct selection of the measuring values was
realized.
1 Distance relay
3 Distance protection characteristic with
RAZOG, ASEA, 1970
2 Distance relay
LG1, BBC
express contact & maximum operating time
t [S]
PAC history
72
Z [Ω]
Distance characteristic
PAC.SPRING.2008
73
The impact of the electric arc
resistance on the distance
measurement was a main
issue for a long time.
When the corresponding phase selection contacts of
voltage and current were from the same auxiliary relays it was
simple to justify the contacts to open and close at the same
time or to open the current circuit a short time before the
voltage circuit and close one a short time after another.
A new measuring principle based on comparison of the
peak values with rectified values, was introduced with the
distance relays SD4. A bridged-connector rectifier allowed a
comparison of any combination of voltages and currents for
the estimation of a difference and the estimation of impedance
and power (direction). Mixed impedance characteristics
(blocking of the circle characteristic along the R-axis) were
available to eliminate the resistance of electric arc from the
estimation of the distance.
The Impact of Arc Resistance and Power Swing
The impact of the electric arc resistance on the distance
measurement was a main issue for a long time. Very early
the utilities performed extensive and systematic short circuit
tests (e.g. Bayernwerk AG in their 110-kV-transmissionline-grid (1926/27) and Preussenelektra (1929) - both in
cooperation with the vendors - AEG, BBC and Siemens.
Under impedance-startup in off-peak periods was tested
for suitability during these tests and new requirements for
further improvements were found. At first, they tried to
eliminate arc resistance with real reactance relays. BBC and
Siemens provided the first solutions in 1928. Maloperation
of relays was observed when power swing occurred between
power plants (seen as short circuits by the relays). This was
frustrating for the engineers. Power swing blocking and power
swing relays were developed. Gutmann,H., AEG patented the
4 Distance relay
RD7, 1958
modified impedance measurement in 1944. The measuring
value of the modified impedance element was:
Z =
U +ˆ k ⋅ I
I
An arcing reserve of 60% was possible with consideration of
line angle at the relay’s trigger point.
100 % of Line Length with no time delay
Starting in the 50's of the last century, fast distance relays
in connection with automatic reclosers were widely used for
the detection of lightning strike faults over the whole length
of the line with no time delay - the "overreach".
An auxiliary device was used to enlarge the zone of the first
stage up to 115% of the length of the protected line . After the
first trip, the value was decreased to the common 85…90% after an unsuccessful reclosing there was guaranteed selectivity
for the second trip. Use of a power line carrier (PLC) channel
for accelerating the trips on both sides of the line allowed
instantaneous protection of the whole length of the line
with the 15%-overreach. This approach was used where PCL
connections were available (remote control, phone, remote
measurement etc.). The first installation was realized in
Germany in the 220 kV grid of Preussenelektra in 1955.
At the end of the 60's distance protection was extended
with "distance dependent directional comparison protection
6
Observing the Siemens impedance protection when energizing a 50 kV line
5 Fast distance relay
SD36, AEG 1986
PAC.SPRING.2008
PAC history
74
7Circuit for measurememt of the impedance
Self-supervision plays an
important role in
improving the performance
of distance relays.
systems". In these devices the directional information and the
measured distance are evaluated. The comparison of distances
is performed in the first stage of distance protection only.
Several methods are used for tripping. In the United States it
was quite common to use "blocking" - the tripping command
of the own protection is blocked by the PLC-signal of the other
station. Another possibility is "permissive intertripping". If a
fault occurs and the device should trip, a permissive signal is
provided to the other end. Last, but not least, "inter-tripping
" should be mentioned. In that case the distance protection
trips its own circuit breaker without a signal from the opposite
station. This is also communicated to the other end –it
"inter-trips". This scheme realizes a backup protection - at the
opposite site neither a distance estimation nor an estimation of
direction is necessary.
In the relay SD14, developed by AEG in 1954, the
directional element was realized with a small moving coil
relay instead of a plunger coil system. The mode of operation
is comparison of absolute values of V + I and V – I (as in the
N-Relays with balanced-beam element 30 years before). Now
a higher sensitivity was reached - 1 % of nominal voltage at
nominal current. A special series element allowed an angle
of up to 30° (inductive) required when used in medium
voltage cable systems. Increasing the pressure of contacts for
high-sensitive distance relays allowed a further improvement
of reliability. A big advantage was the direct-CT-powered
operation - it was useable in stations without batteries. The
switch to the next stage was realized with " synchronous time
relays" (with synchronous motor).
In the USA in almost all cases three balanced-beam-relays
were used - permanently connected with voltage and current.
They were set up according to three stages with different time
settings. Thus, a stepped characteristics was available. German
Railways used a similar system.
„Self-Supervision"
Some of the first distance relays were equipped with voltage
transformer supervision. The N-relays (PAC World, Winter 08
issue, Figure 4) had a built-in voltmeter. Another possibility
was the use of external or internal glow-lamps. Aigner
developed a rotating -field discriminator for supervision of
interruptions of one or two phases and of the existence of a
right rotating field. A fault in the current circuit could be only
detected with the startup of sensitive zero-sequence relays.
The loss of auxiliary voltage could be visualized with a flag
relay. Development of microprocessor-based relays allowed
a further self-supervision (measuring values, CPU-failures,
trip-curcuit, circuit breaker supervision…).
Guidelines for Distance Protection - Further Steps
Lessons learned in the time before World War II show,
that a joined operation of adjasent protection systems was
8 Transmission line protection distance
9 D istance relay 7SA500,
I
Current circuit
relay LZ91 (BBC)
Withdrawable
boards allow
quick fix of
problems in
solid state
distance
relays.
PAC.SPRING.2008
U
Voltage circuit
Siemens, 1986
10
D
istance
relay DD2, EAW
75
not successful in any case and that the vendors did not allow
that. The same problem occurred when different vendors were
used in the same grid. That is why the utilities defined their
requirements to allow the usage of relays of different vendors
in one grid. The pre-condition to do that was to harmonize
the operation behavior of relays. The German VDEW
proposed an "Agreement of Utilities for Harmonization of
Distance Protection" in 1951. The paper describes relays
of the following vendors - AEG - SD4, BBC (L3, LG1- and
LG2-Relays, Figure 2) and Siemens RZ24-/ RK4-Relays.
The BBC relays were reactance protection, while AEG
and Siemens provided impedance relays (elimination of arc
resistance with a mixed-impedance add-on). The guideline
defines startup (2-and 3-pole, range of overcurrent or under
-impedance-startup); voltage; dead zone; first-zone-time;
smallest measuring impedance; maximum operating time,
detection of doubled earth faults; power consumption.
Other recommendations were regarding the mounting and
the usage of the DC measurement (shunt instead of interposing
transformers). The recommendation for timing elements was
motor drive instead of clockworks (higher moment of force
and improved resistance against contamination). Ulbricht,R.
und Kadner,G. publish a bulky guideline for time grading
coordination with distance protection in the GDR (Eastern
Germany) in 1958. The document considers the special
circumstances in the GDR after World War II - 13 different
types of relays with different characteristics were available.
Therefore, the document describes selective time interval
and impedance, single and parallel lines, impact of measuring
failures at transformers, arc resistance, detection of doubled
earth faults; maximum operating time and calculation of
short-circuit currents.
ASEA (Sweden) produces the distance RYZKC relays
since 1950. To decrease tripping time distance protection
was used as busbar protection in transformer infeeds. EAW
(GDR) introduced RD7 in 1952. Pushing the button (Figure
4) performed a functional test of the relays (only if the tripping
circuit was interrupted). Austrian Rail (ÖBB) used an auxiliary
distance relay in their 16 2/3 Hz grid since 1957. It was
developed by Gutmann,H, AEG, and was named SD4/
WZD0. It was a joint initiative with German Rail and AEG
and could be used for non-fading earth-faults as well (the other
phase was earthed in another station, and then a doubled earth
fault occurs and the faulty line could be tripped).
Backup Protection
Lively discussions regarding the use of backup protection
started in 1960. Norway, Russia and England preferred
doubling protection in the EHV grid. They used two similar
or equal relays. An expert from the United States reported the
„ breaker-and-a-half approach" - the reserve was the circuit
breaker, because failures of breakers and tripping circuits are
more likely than with relays and measuring transformers. The
EHV grid in Germany uses a backup relay per feeder ("main"
and "backup" or "system 1" and "system 2"). Both systems are
separated; up to today, it is quite common to merge different
type relays (e.g. distance and differential protection) of
11 Distance relay RAZOG, ASEA, 1970
Rb
Rb
Rb
X1
{
zone 3
zone 2
zone 1
R
Resistive reach setting
12
Reactive reach line
Distance relay PD531, AEG, 1991
This is one
of the examples
for the usage of
microprocessors
in distance
relays
13 Distance relay 316LZ (ABB,1990)
PAC.SPRING.2008
The first
distance relay
with polygonal
characteristic
was produced
by ASEA
in 1970
PAC history
76
14 Distance relays THR and OHMEGA
Terminal rack of type THR
from 1975
The 1999 OHMEGA version
different vendors. To avoid malfunction a "2 out of 3 circuit"
was discussed often but did not became established.
Introduction of Electronics
The first electronic distance protection was used in 1959.
The French EdF reported the commissioning of a transistor
based distance protection in the 200 kV grid. In its first year
it worked properly in 38 cases (of 40 faults). According to
vendor’s publications the relay needed only 2 VA (in current
and voltage) and the stepped characteristic should be nearly
perfect, not depending on the short-circuit current. Other
documents describe an English distance relay with Mho-circle,
based on transistors. It was developed for the South African
EHV grid and was proved of value. It should be mentioned
that the vendor at this time warned against big enthusiasm for
“transistor relays”.
The sophisticated electromechanical relays in
bridge-connected rectifier circuit were better and more
economic at this time. The first distance relay with polygonal
characteristic (Figure 11) was produced by ASEA in 1970 the three-phase static relay RAZOG (Figure 1) with a shortest
operating time of 21 ms.
Mann and Morrison, UNSW (Australia) developed
algorithms for the calculation of line impedances in the same
year. Rockefeller,G.D., Westinghouse; published an IEEE
paper one year before and patented a digital distance protection
15
Test distance relays PD551, AEG and
7SA5, Siemens in a 750 kV grid
Ukraine
750 kV
Hungary
in 1972. Before that he did together with Gilchrist,G.D.,
(PG&E) a field test with digital line protection PRODAR and
a computer in a 230 kV substation in 1971.
It is worth to mention the EHV directional comparison
protection RALDA (ASEA) from 1976. It is based on
superimposed components principle and achieved a time
for estimation of a fault of 2.4 ms. Cubicles for each feeder
with swing frame and plugs, introduced at this time, allowed
an easy change and combination of withdrawable boards
(Figure 9). Beginning in 1985, distance protection with digital
measurement was used in the medium voltage as well - AEG
introduced the fast distance relay SD36 (Figure 5).
Examples for the usage of microprocessors in distance
relays are: 7SA500 (Siemens, 1986 - Fig.9); 316LZ, (ABB,
1990 - Fig 13); PD531, (AEG, 1991 - Fig.12); DD2, (EAW,
1996 - Fig. 10) and OHMEGA, (Reyrolle, 1999 - Fig. 14).
These solutions were the quantum leap - from impedance
depending short circuit protection to multifunctional
feeder-relays. The development of the different generations of
numerical protection and their advantages will be covered in a
special article later.
Despite of comprehensive tests, type tests according to
international standards by the vendors, certifications and
commissioning tests with sophisticated test sets, staged
short circuit faults are still valuable. In these tests vendors,
utilities and universities contribute. A good example was the
international line 750 kV Zapadno-Ukrainskaja (Western
Ukraine)- Albertirscha (Hungary) with the distance relays
PD551 (AEG) and 7SA502/511 (Siemens) Figure 15.
A special challenge for protection engineers was the
commissioning of a six-phase transmission line 93-kVGoudey Station - Oakdale, NYSEG (US) in 1992. Sambasivan,
S and Apostolov,A.P. solved the protection problem with
digital differential relays LFCB, directional comparison relays
LFDC, distance relays LFZP and a high-speed programmable
logic device LFAA (all from GEC ALSTHOM) (Figure 16).
Any comments or questions please send to:
walter.schossig@pacw.org
www.walter-schossig.de
16 Protection of a six-phase line or distance
relays OPTIMHO LFZP, GEC ALSTHOM
GOUDEY
OAKDALE
750 kV
A-C-E
B-D-F
21 km
373.3 km (78.3%)
477km
103.7 km
LFCB
87
LFDC
78
21
LFZP
21
21G
62
MCTI
67G
10 kV
330 kV
PAC.SPRING.2008
Six-phase line protection, one end, three-phase group A-C-E or B-D-F
Marco C. Janssen
I think
77
Do we
really need
Smart Grids?
The buzz word of our time is
“Smart Grids”. It seems that suddenly
everything has to become “Smart”.
When I look at this it makes me start
to think…
way. On the other hand however I
get the feeling that we are making
things unnecessarily complex by
throwing technology at any pro­
blem we try to solve. So what is
the true answer?
Does our sudden interest for
“Smart Grids” mean that up to
now everything we did was stu­
pid? I don’t think so.
When I look back at my first years
as an engineer in the power indus­
try I have to say that I had some
extremely smart colleagues who
tried to teach me everything there
was to know about power systems
and their behavior. And I can say I
had to learn a lot!
Until recently smart engineers
handled the most complex issues
without grids being as “smart” as
we believe everything should be
today. Given the fact that electri­city
has become a reliable commodity
in our society and that we all hea­
vily rely on it, must mean that they
have done something right.
Why is it then that we believe that,
to solve the issues of our ages,
we have to throw technology at
e­verything? I was brought up with
the philosophy that simple was
better.
So why are we making things
more complex then? In some ca­
ses we make them so complicated
that even the smartest of engineers
have trouble following what is
going on. Are we trying to com­
pensate for the fact that we are no
longer smart enough ourselves or
is there some other, deeper, reason
why we are doing this?
When I try answering these ques­
tions myself I struggle to come up
with answers. On the one hand I
strongly believe that a combina­
tion of all the available information
existing today within so-called is­
lands of automation, can lead to
better and even simpler solutions.
Which allow utilities to deal with
today’s challenges when operating
a power system in a more efficient
As so often I believe the truth lies
in the middle. Yes, we can improve
the utility business by combining
information and using the newest
technologies. On the other hand I
also believe that it is wise to think
before we act. We should remem­
ber that automation for the sake
of automating has never led to
cost effective solutions. So pursu­
ing “Smart Grids” for the sake of
having “Smart Grids” will in my
opinion not lead to long-lasting,
feasible solutions.
So what should we do? We should
never forget to ask at least one
important question. “Why are
we doing this?” When we start
answering this question we will
most likely find the right answers
to what we really need to do and
when.
So I look forward to seeing many
new “Smart Solutions” that are be­
ing built for all the right reasons.
PAC.SPRING.2008
Biography
Marco C. Janssen
graduated the
Polytechnic in
Arnhem, The
Netherlands and
further developed
his professional
skills through
programs and
training courses.
He is President and
Chief Commercial
Officer of
UTInnovation LLC
– a company that
provides consulting
and training
services in the
areas of protection,
control, substation
automation and
data acquisition,
and support on the
new international
standard IEC 61850,
advanced metering
and power quality.
He is a member of
WG 10, 17, 18, and
19 of IEC TC57, the
IEEE-PES and the
UCA International
Users Group.
reports
industry
CIGRE SC B5
Protection
and
Automation
B5 is one of 16 Study
committees of CIGRE.
Its scope is to facilitate
and promote the pro­
gress of protection and
automation.
79
The business environment for utilities has changed drastically due to the
restructuring of the world electrical energy markets. The profitability pressure has demanded
reconsideration of the complete secondary system approaches, to identify and beneficially
utilise all possible synergies between the tasks of protection, control and monitoring. All
assets have to be used in more profitable ways, whilst the security of on-demand energy
supply is increasingly important, due to the increasing costs for energy not supplied and the
severe impacts that blackouts now have on communities, industry, commerce and nations.
SC B5 covers all the secondary equipment and systems installed within substations. This
includes power system protection, substation local and remote control, automation, metering,
monitoring and recording.
Priorities
Automation of substations, with integrated protection and control systems and the use
of the new IEC 61850 Standard are major industry trends. The application of IEC 61850
will be extended to further areas and its impact will demand continued review and study
to detect any general problems, so that they can be addressed before they become too
widespread. CIGRE SC B5 provides a unique channel of feedback to IEC in this respect.
PAC.SPRING.2008
by Ivan De Mesmaeker, ABB, Switzerland
Relevant issues related to the IEC
61850 standard are:
Functional testing of IEC 61850
based systems
Applicat ion of protect ion
schemes based on IEC 61850
Engineering Guidelines for IEC
61850 based systems
Maintenance strategies for
Substation Automation Systems
Impact of security requirements
on SAS
The introduction of digital
hardware and numerical protection
technology has greatly transformed
the planning, operation and
maintenance practices for protection
systems. Design engineers now
require appropriately adapted
guidelines to support their work.
Several working groups are preparing
reports about on-going trends
and offering recommendations
for the protection of generators,
transformers, shunt reactors,
overhead lines or cables and busbars.
Modern numerical relays are
highly integrated and contain a great
number of protection and additional
functions. Special attention is
given to the increasing trend for
functional integration. “Bay Units”
for combined protection and control
are now accepted at distribution
levels and this trend may migrate to
the transmission levels. Numerical
relays are widely self-monitored.
Regular routine testing will
therefore be increasingly replaced
by condition-based maintenance,
depending on how comprehensive
the self-monitoring is.
System-wide monitoring
and protection
Wide area disturbances due to
loss of stability or voltage collapse,
still occur and may become more
probable in the future, with higher
system loading and by regularly
operating plant and power systems
towards their design limits and
capabilities. On the other hand,
wide-band communication links,
adaptive digital protection and
GPS synchronized data acquisition
provide platforms for novel system
wide monitoring and protection
techniques. In many countries a
large part of the business is the
retrofitting of existing plants and
Communications
within substations are
covered by the new
and expanding
IEC 61850 standard.
1 Evolution of number of devices for a protection and
control system
Line
5
Feeder
3
4
4
3
8
8
4
39
39
39
1960
1970
Control
PAC.SPRING.2008
1980
3
4
32
3
2
1990
1
7
13 Cubicles, > 50 Devices
Busbar
4
6
47 Cubicles, > 100 Devices
4
6
56 Cubicles, > 140 Devices
Transformer
12
66 Cubicles, > 160 Devices
11
68 Cubicles, > 180 Devices
CIGRE B5
industry reports
80
2000
4
4 Cubicles,
"Soft" Devices
2010?
systems because of life-expiry, or
because of recommendations about
the need to change current practices.
The development of life-cycle
maintenance and risk management
strategies are therefore expected.
Software tools for dynamic
simulation, management of relay
settings, disturbance or fault
record analysis, or how to write
specifications are improving.
Emphasis on education is
a challenge, considering that
protection is generally not a topic
dealt with to any significant depth
by colleges and universities, and
that engineers entering in the power
engineering sector in general are
becoming rare.
Numerical technology combined
with advances in information
management contributes to the
more efficient management of
power networks, but it introduces
problems and issues in four
main areas: level of integration,
standardisation, information
management, wide area monitoring
and protection.
The integration of ever more
functions into fewer devices and
systems has been an increasing
trend – especially over the last 10
years or so. Figure 1 indicates the
evolution of the number of devices
for a protection and control system
covering a station with six 220 kV
lines and eight 16 kV feeders.
Protection function integration
is now the norm and combined
with high level of self-supervision
in numerical protection devices
actually supports a higher degree
of integration - a trend that will
continue in the future.
The moder n protect ion
technology facilitates new solutions
and functions to tackle several
fault management problems, such
as the protection of combined
cable-overhead lines (adaptive auto
reclosing with ability to distinguish
potentially transient overhead line
arcing faults from solid cable faults)
or the protection of parallel and/or
multi-terminal lines.
Standardization
Standardization covers two main
aspects: Typical Bay and Station
levels and Communication.
Independently of the applied
technology, it is possible to define
the required functionality and
performance of each protection and
control function (tripping times,
precision, etc) for each type of Bay,
in each type of substation. Users can
define additional requirements, such
as the permitted level of functional
integration, the physical scheme
architecture, the requirements
concerning DC auxiliary/tripping
supplies, test facilities, wiring and
inclusion of some specific devices.
Functional requirements can also be
listed at the Station level, covering
HMI (Human Machine Interface),
event and alarm lists, etc.
Specifications need only be
functionality based, with reference
to a single line diagram, rather than
detailing specific protection system
devices.
Communications
Communications in substations
should assure interoperability
between compliant Intelligent
Electronic Devices and functions
within the substation. They should
be future-proofed, i.e. able to
cope with the fast developments
in communication technology
compared to the more slowly
evolving application domain of
power systems.
These are very ambitious goals,
which demand that all secondary
substation devices and functions
must be examined with regard to
their communication performance
and requirements.
Guide for Breaker
Failure Protection
Published
by Roger Hedding, ABB, USA
How do u tilities handle
backup protection? What are the
advantages of using local backup
over remote backup? How is
breaker failure protection being
implemented by utilities? What
are the pitfalls in using the breaker
auxiliary contact for breaker
position? Where do you go to get
these answers? Prior to 2005 no
guide existed in applying breaker
failure protection to answer any of
these questions. The only previous
article written by the PSRC was
in 1982. An IEEE Power System
Relaying Committee Working
Group w rote a report t itled
“Summary Update of Practices
on Breaker Failure Protection”
and published it in the IEEE
Transactions on Power Apparatus
and Systems. Vol. PAS 101, no.3,
pp 555-563. March 1982.
To answer these questions and
provide a reference for engineers to
for future generations, the IEEE PES
PSRC Substation Subcommittee
formed a working group to write a
guide on this subject. This working
group was formed in 2000. 62
industry experts from utilities,
manufacturers, academia and
government agencies put in many
hours of effort in writing and
The Power System
Relaying Comettee is in
the Power Engineering
Society of IEEE.
reviewing the guide before it was
published in 2005. The result is
IEEE STD C37.119 Guide for
Breaker Failure Protection of
Power Circuit Breakers – 2005.
The following are excerpts from
the guide Remote versus Local
Backup.
If remote backup is employed,
then the time delayed overreaching
element (Z2) of the relay at a remote
substation operates for a fault on
line BC when local breaker fails to
clear the fault on a line. Operation
of remote breaker interrupts the
load connected downstream of it. If
local backup is used, when a breaker
fails, local breakers clear the fault.
The load is not interrupted in this
case on the line with the remote
substation. Local backup provides
faster clearing and less loss of load
than remote backup:
In the basic scheme for breaker
failure protection, as soon as the
relay issues a trip to its breaker, a
breaker failure timer is started. If
the fault still persists after the timer
times out, then a breaker failure
condition is declared, and the
breakers connected to the bus are
tripped.
Breaker Failure Initiate (BFI) is
the signal coming from the primary
PAC.SPRING.2008
by Roger Hedding, ABB, USA
IEEE PES PSRC
industry reports
82
protection to trip the breaker. An
overcurrent fault detector (50BF) is
employed to determine if the fault
is still present. 50BF will drop out
if the breaker clears the fault. The
guide discusses issues related to the
setting and drop out of the fault
detector (50BF). The timing for the
scheme is seen below. (Fig. 1)
In EHV transmission systems,
the total fault clearing time needs
to be less then the power system
critical clearing time plus some
margin. The power system critical
clearing time is a function of the
steady state stability limit for the
power system. Since the critical
clearing time to maintain system
stability is greater for single line
to ground faults than three phase
faults, some schemes employ dual
timers. (Fig. 3) The 62-2 timer can
be much longer than 62-1.
For lower voltage systems, the
total clearing time is chosen to limit
damage to equipment. Some faults
such as transformer or reactor faults
have such small currents that a fault
detector can not be used. In those
cases, a breaker 52b contact is used
for indication of breaker operation.
(Fig. 4) In some cases where there
is a known problem with a breaker
before it’s called to trip, a bypass
scheme can be employed. (Fig. 5)
In this scheme, if there is low gas
pressure and the primary relay calls
for a trip, the breaker failure scheme
is bypassed and the surrounding
breakers are tripped immediately.
Other schemes are also discussed.
A section of the guide deals with
design considerations for the
breaker failure scheme. Several
factors need to be considered.
Among them:
Scheme operation should only
occur when expected and desired.
Scheme operation should be
independent of the types of failures
detected in the breaker. For
example, the failure mode of the
breaker trip coil should not effect
the schemes ability to detect the
failed breaker and to properly
isolate it from the power system.
Scheme operation during loss of
dc power to the failed breaker.
Sufficient overlappin g of
protection and isolation switches
to allow maintenance and overall
testing of the scheme.
Proper application of auxiliary
tripping relays.
Selection of properly rated inputs
and outputs when the breaker
failure is integrated as part of the
equipment protection package and
when user selectivity in rating is
provided.
Proper application of dc circuits
and avoidance of mixing supply
sources.
Minimizing the impact of dc
transients.
Other sections of the Guide deal
with factors that influence settings,
communications based breaker
failure schemes, and end to end
testing.
The guide is available through the
IEEE Standards Department
IEEE C37.119 Guide
for Breaker Failure
Protection
2 Basic Breaker Failure
Protection scheme
62-1
50BF
BFI
Scheme Output
Protection scheme
50BF
A
B
C
62-1
2 of 3
AND
Timer
AND
Timer
Breaker Failure
Scheme Output
OR
OR
AND
62-2
BFI
4 Breaker contact use for breaker operation detection
62-1
BFI
52a
AND
OR
BFI
Timer
Breaker Failure
Scheme Output
50BF
5 BFP bypass scheme
Margin Time
Breaker Interrupt
Time
Breaker Failure
Timer
3 Dual-Timer Breaker Failure
1 Total fault clearing time
Protective
Relay Time
AND
Fault Cleared
50BF current
detector
Standard Breaker
Failure Scheme
BFI
OR
Breaker Failure
Scheme Output
62-1 BF Timer Time
BFI
Fault Occurs
Aux
Trip
Relay
Time
Local Backup Breaker
Interrupt Time
Transfer
Trip
Time
Remote Breaker
Interrupt Time
AND
50BF
Low gas
pressure
contact Timer
100msec
PAC.SPRING.2008
reports
conference
83
IEEE T&D
Conference
2008
Chicago,
Western Power
Delivery Automation
Illinois, USA
page 89
Spokane,
Washington, USA
page 88
Texas A&M
Conference for
Protective Relay
Engineers
The 9th International
ConferenceDevelopment in
PS Protection
Glasgow, UK
page 86
College Station,
Texas, USA
page 86
PAC conferences
around the world
2008 Power
System
Conference
Clemson,
South Carolina,
USA
Protection, Automation
and Control conferences
around the world provide
forums for discussions and
exchanging ideas that help
the participants resolve
the challenges that our
industry faces today.
page 85
DistribuTECH
2008
Tampa ,
Florida, USA
page 84
PAC.SPRING.2008
from around the world
conference reports
84
The Tampa
Convention Centerwas the conference
venue in Florida
DistribuTECH 2008
held in Tampa, Florida
The focus of the conference
was new technologies and
their impact on the future
of the industry.
Th e 1 8 t h D i s t r i b u T E C H
Conference & Exhibition was
held from January 22 to January
24, 2008 at the Tampa Convention
Center in Tampa, Florida. It is one
of the key events in North America
that gives the opportunity to many
electric power system specialists
to learn about the latest trends in
technology and exchange ideas
about the future of our industry.
The areas covered by the event
include automation and control
systems, information technology,
transmission and distribution
PAC.SPRING.2008
engineering, power deliver y
equipment and water utility
technology.
DictribuTECH was attended by
more than four thousand specialists
from around the world. They visited
and discussed the latest technology
with approximately three hundred
exhibitors, representing more than
fifty product groups and more than
twenty unique services.
The conference was preceded by
the Utility University that included
full and half-day tutorials on subjects
of great importance to the industry.
Industry
leading
manufacturers participated in the
exhibition
The full day tutorials of interest to
the PAC community covered:
Cost-effective distribution
reliability improvement
Distribution automation –
strategies for success
Substation automation projects:
design issues, alternative approaches
& cyber security considerations
Substation protection, controls
& communications in the new
century
Cyber security risk management
Using the IEC 61850 standard
for communication networks and
systems in substations
The conference started with
a keynote session that included
presentations by Spencer Abraham,
the tenth Secretary of Energy
in United States history, Don
Cortez - Division Vice President of
Regulated Operations Technology
for CenterPoint Energy, the nation’s
third largest combined electricity and
natural gas delivery company and Jeff
Sterba - Chairman, President and
CEO of PNM Resources.
The conference papers were
presented over three days in six
tracks, four of which included
subjects related to PAC. The
substation automation track had
sessions covering utilities experiences
in substation automation, IEC61850
85
DistribuTECH
provides more current
resources, new
industry technologies,
and
fast-track
networking
opportunities.
Clemson Power Systems
Conference 2008
An exhibit area allowed eight of
application and experiences,
making systems interoperable –
the standards evolution continues,
designing and deploying successful
substation automation and a look at
standards-based substation network
implementations designed for
extensibility, resiliency and security.
The distribution automation track
included sessions on pulling together
multiple technologies to become the
“utility of the future”, innovative
integration of protection and
automation for feeder restoration,
keeping up with communications
- the path to EZ automation and
extracting information out of the
automation data well.
The TransTECH track included
a session on wide area monitoring
systems and phasor measurements
and their impact on the reliable
operation of the grid.
PennEnergyJOBS Career Fair at
DistribuTECH provided a selection
of the top industry employers
looking to recruit skilled energy
professionals.
Several exhibiting companies
sponsored a Ford Mustang Giveaway
at the end of the show. Attendees that
visited the booths of all participating
vendors had to be present at the
drawing. The winner claimed his
prize within two minutes.
the leading industry companies
in the field to demonstrate the
latest solutions that they offer
to the market.
The 2008 Power S ys tems
Conference was hosted by
Clemson University at the Madren
Center, Clemson, South Carolina
from 11 March to 14 March
2008. The focus of the seventh
annual conference was system
issues associated with Advanced
Metering, Protection and Control,
Communication and Distributed
Resources.
The program included a number
of tutorials by leading power industry
companies. All tutorials were
available to all registered attendees
at no additional cost and covered the
following topics:
Practical Applications
Protective Relaying Seminar
Renewable Energy Challenges:
Present and Future Directions
Substation Automation IEC
61850
L eading indust r y expert s
were keynote speakers: Intelligent
Grid - The Road Ahead - Bogdan
Kasztenny, GE Multilin; Power
Engineering in a War Zone - Jim
Hicks, Shaw Engineering Service
Group; Future of the Smart Grid Matt Smith, Duke Energy; PHEV's:
Strategic Opportunities for Utilities James Poch, Plugin Hybrid Coalition
of the Carolinas; Innovations in
Technology Changing Power Systems
Today - Ed Schweitzer, SEL; Future
of Nuclear Energy - Stephen Byrne,
SCE&G
Four panel sessions gave an
opportunity to the interested
participants to discuss:
Integrating plug-in hybrid electric
vehicles with distribution systems
Integrating advanced metering
with distribution systems operation
Synchrophasors: principles,
application and implementation
Utility of the future
The seven paper sessions included
papers in the following groups:
Protection of distribution
systems with distributed generation;
Stability of distribution systems ;
Renewable energy in power systems;
Advances in digital protection;
Synchrophasors ; Wide area
monitoring & control; IEC 61850
applications.
PAC.SPRING.2008
from around the world
conference reports
86
Texas A&M Protective Relay
Conference, USA
Developments
in Power System
Protection
2008
The success of the conference
shows that at this time of
rapidly changing technology,
a period of four or even three
The Texas A&M 61st Annual
Conference for Protective Relay
Engineers was held from 31 March
to 3 April 2008 at College Station,
Texas. The conference was hosted by
Texas A&M University. As Prof. B.
Don Russell, Chair of the conference
said in his Welcome address “…the
conference has provided the best
available information on protective
relay applications and technology.
With the changes that have occurred
in the electric power industry and
with the business emphasis on
efficiency and cost savings, the relay
conference is even more important
than ever.”
Two pre-conference events were
offered to the participants:
A presentation on the new “Guide
for Protective Relaying Application
to Distribution Lines” produced by
a working group in the IEEE Power
Systems Relaying Committee.
Presentation on Ethics in Engineering Practice.
Manufacturers seminars discussing
latest advancements in protection
technology were also held at the
College Station Hilton before the
start of the conference.
The papers were presented in
several general sessions and tracks:
Power Engineering Track
Industrial Track
Communications Track
Real World Experience
Three Break-Out Sessions
discussed Phasor applications,
Commissioning and testing of relays
and Distance element challenge.
The papers presented during
the different sessions triggered
interesting discussions. This was to a
great extent due to the practical focus
of the presentations.
Demonstrations of the latest
technology and discussions of
their principles and applications
help the participants improve their
knowledge in the field of protection
and control.
years between the conferences
is too long.
Th e 9 t h I n t e r n a t i o n a l
Conference on Developments
in Power System Protection was
held from 17 - 20 March 2008
in Glasgow, Scotland, UK. This is
the largest specialized protection
conference in Europe that is held
at three or four years intervals at
different locations.
The conference venue was the
Crowne Plaza Hotel in Glasgow.
This is Scotland’s largest city with
a population of 600,000. It is the
commercial capital of Scotland and
one of Europe’s top 20 financial
centers. The hotel overlooks the
River Clyde and is located next to the
Scottish Exhibition and Conference
Centre (SECC) and opposite the
Glasgow Science Centre.
The conference
was hosted by
Texas A&M
University
The attendees enjoyed not only
their time together, but also an
art collection of international
significance which includes
works by Rembrandt, Botticelli,
Van Gogh and Lippi.
PAC.SPRING.2008
87
The conference was
held in
Glasgow, Scotland,
UK
Glasgow
is the
largest city in
Scotland
A one day tutorial on IEC 61850
and its application to protection
systems was presented by some of
the leading industry experts with
the idea to improve the attendees
understanding of the standard
and help them in its successful
implementation in different
projects.
The conference started with two
keynote addresses:
Trends in Protect ion and
Substation Automation Systems
and Feed-backs from CIGR E
activities was delivered by Ivan de
Mesmaeker, Chairman of Study
Committee B5 of CIGRE. He
addressed the main important
issues regarding protection and
substation automation systems:
the possible level of integration,
the standardization aspects and
the impact of IEC 61850, the
information technology and the
overall system protection scheme.
The second keynote speaker
was Javier Amantegui, Protection
Manager of Iberdrola and
talked about the challenges and
opportunities faced by utilities
using modern protection and
control systems.
The papers selected by the
conference organizing committee
ranged from research concepts
and ideas to technical issues and
industrial applications.
The papers belonged to the
following main categories:
Relay design and protection
principles
Impact of utility changes on
protection
Funct ional integrat ion of
protection and control
The papers were presented in
three forms:
Oral presentation sessions
Short presentations sessions
Poster sessions
A dedicated exhibition ran
in parallel to the DPSP 2008
conference, covering a range of
products and services.
The Conference Dinner was
held at the prestigious Kelvingrove
Art Gallery and Museum, one of
Scotland 's most popular tourist
attractions.
The conference
was held at the
Crowne Plaza
hotel next to the
SECC
PAC.SPRING.2008
88
from around the world
conference reports
Western
Power Delivery Automation
Conference 2008
John Tengdin delivered the keynote address at the opening of
the conference.
The tenth Western Power
Delivery Automation Conference
was held from 6 April to 10 April,
2008 at the recently renovated
Davenport hotel in the center of
Spokane, WA. The conference was
organized by Washington State
University and is an annual event
which focuses on the fast-changing
issues of automation and control
of electric power systems and
substations. This two-and-a-half
day conference is a gathering
place for automation specialists
interested in:
Net work Protocols and
Communications
Case Studies and Applications
Security
Control and Automation Logic
S C ADA and W ide Area
Measurements
Engineer ing and Project
Management
The conference started with
a keynote presentation by John
Tengdin, OPUS Publishing, Life
Fellow of IEEE. He talked about the
fact that this year’s program bears
little resemblance to that of 1999
or 2000. This is mainly because
during these few years Ethernet in
substations and with it IEC 61850
have come of age. This is proven by
the nine papers in the conference
program that include those topics
in their titles. The focus is on the
use of standards that are having
significant impact on the design of
new substation and power delivery
automation systems. This is very
timely, as five new or updated IEEE
substation related standards have
been approved in just the last year.
The changes to the “language” of
Paper session
during the
conference
The conference
was held at
the historical
Davenport
hotel
PAC.SPRING.2008
substation engineers (IEEE C37.2
Device Function Numbers and
Contact Designations), namely
the introduction of the use of
acronyms, were opposed by
some engineers, but survived the
working group ballot process.
The twenty papers selected
by the program committee were
presented during five sessions.
This is one of the few conferences
that give enough t ime for a
detailed presentation, followed by
questions and discussions between
the audience and the presenting
industry experts.
The papers presented at the
conference not only introduced
some new developments and
applications, but also delivered
valuable concepts and information
related to retrofitting substations,
selecting the right communications
topolog y and improving the
engineering process.
The location of the exhibition
area right next to the conference
sessions room allowed the
participants to use the coffee
breaks and the time after the
end of the paper sessions to see
demonstrations of the latest
hardware and software tools
exhibited by leading manufacturers
in the field of power delivery
automation and communication
networking technology.
89
One of the goals of
the conference was
to help the industry
with their
need to educate
young engineers.
The IEEE PES T & D Conference
and Exposition was held in Chicago,
Illinois from 21 to 24 April 2008.
It brings together power-delivery
professionals with many different
areas of specialization, including
transmission and distribution
planning, protect ion and
control, substation engineering,
dist r ibut ion automat ion,
communicat ions, renewable
e n e r g y, o p e r a t i o n s , a n d
maintenance. The McCormick
Place was the conference venue.
This conference provides a forum
for discussions of a wide range of
topics related to the present and
future of our industry.
The technical program was
designed to address the concerns of
the industry and the impact of new
technical and business solutions
that support the operation and
maintenance of the elec t r ic
transmission and distribution
system at peak levels, while
maintaining the required reliability
and security under maximum load
and dynamic system conditions.
One of the goals of the
conference was to help the industry
with their need to educate young
engineers in the fundamentals
of electric power technologies
and the applic at ion of new
communications based intelligent
devices and systems.
The conference program was
divided in several different types
of sessions, covering a wide
range of topics, many related to
IEEE PES
T&D Conference
2008
The theme of the 2008
conference was “Powering
Toward the Future”.
electric power systems protection,
automation and control:
Tutorial Sessions
Education Track
Super Session Panel Sessions
Poster Sessions
Exhibitor Info Sessions
In parallel with the conference
the at tendees v isited the
exhibition hall and discussed
with participating experts the
latest solutions available to meet
the requirements of utilities and
industrial facilities.
Technical tours to the Twin
Groves wind farm, Argonne
National Laboratory, ComEd’s
We st L oop sub st at ion and
Operations Control Center (OCC)
demonstrated real-life applications
of advances technology.
The Conference Reception was
held at the Museum of Science &
Industry and gave the participants
an opportunity not only to enjoy
the exhibits, but also to network
and exchange ideas about the future
of our industry with colleagues
from around the world.
The Conference
Reception was
held at the
Museum of
Science &
Industry
PAC.SPRING.2008
The McCormick Place
was the conference
venue.
Become a PAC World
correspondent:
Report on conferences, symposiums and
exhibitions
Conduct interviews with leading
industry experts
Send information about system
events
Capture with your camera the life of
our industry
Your
photo
To apply, send an e-mail to: editor@pacw.org
photos of the issue
91
Good Morning Spring Photo: Kervin-Peng Yu/ China / Nikon D40X
Photo Competition 2008
These photos were selected for the Spring 2008 issue.
They will be
considered for
the final Photo
of the Year
Competition.
Please, submit
your favorite
pictures for
Summer 2008.
Desert Mood
Photo: Alexander Dierks/ South Africa/ Pentax Optio S5i
PAC.SPRING.2008
Book review
93
Kilowatt
A Novel
You never know who you are
going to meet at a conference or
exhibition. One thing is for sure
– there will be many interesting
people from our industry. But
this time while I was attending
the Western Power Delivery
Automation Conference in Spokane,
Washington I met someone who
is not from our industry, but was
drawn to the exhibition area in the
Davenport hotel by his interest in
electric power and all the issues
related to it.
Upon meeting him, he held in his
hand a book, his book it turns out,
Kilowatt, which is the subject of this
review. It triggered an interesting
conversation and I decided right
then and there that I would find
the time to review this book – even
though it isn’t a technical book, but
fiction.
I think a quote from the web
site http://www.readkilowatt.
com/joe_mchugh.html describes
the author quite well as “… a
professional storyteller, public radio
producer, playwright, museum
director, festival organizer, old-time
fiddler, educational consultant
and home-grown philosopher.
He regularly lectures on the art
and practice of storytelling in the
electronic age and has written two
collections of folktales and humor
and an illustrated children’s book
about the early days of aviation.”
It
is
difficult to
define the category
of the book, because it is
multidimensional. On the surface
it looks like a thriller, because we
have a couple of ordinary people –
two journalists from a small town
radio station – trying to find the
truth about a mysterious power
plant in Texas that is making the
employees sick. They are standing
up against different villains –
ruthless corporate executives and
their cronies, corrupt politicians
and the Russian mafia.
At the same time the book is
philosophical. The subject of time
is directly related to the main plot,
but it is also discussed from the
point of view of our existence in
time and how it changes depending
on our state of mind. The book
raises a lot of other questions (e.g.
the meaning of “clean” power).
We define things based on what
we know, as well as our personal
experience. Something that does
not produce CO2 and radiation
may look clean, but if it caused the
sinking of a Soviet submarine – is
it?
This brings us to a different line in
the story – the moral responsibility
of the scientist while letting the
Genie out of the bottle.
Another difficulty with classifying
the book is due to the technology
used to generate the power in
the rural Texan plant. For us, as
protection engineers, it is clear that
such technology does not exist – so
maybe this will make Kilowatt a
science fiction book. Regardless of
the fact that everything is happening
here – on the planet Earth, and today
– not somewhere in the future.
It is impossible to talk about this
400 pages book in the limited space
we have available here. But what is
important to say, is that this is a very
well written story that keeps you
turning the pages trying to find the
answers to the many questions that
Joe McHugh raises:
How does the power plant work?
What is the energy source?
Who is going to win – Alice and
Reb or the villains?
What happens to the inventor
of the technology?
And many more...
Well, I am not going to tell you.
You will have to read the book.
Kilowatt by Joe McHugh
Published by Calling Crane Publishing
ISBN # 978-0-9619943-4-1
PAC.SPRING.2008
by Benton Vandiver III, OMICRON, USA
The Art of BBQ Cooking
hobby
94
A Tasty
Hobby for
Those with
Patience
I was asked by Alex
what hobbies I had, in
particular anything that
was out of the ordinary.
I related a few of them
Benton, the BBQ participant,
shares with us some of his famous barbeque recipes.
to him and he zeroed in
on the barbeque (BBQ)
team that my wife I
participated on in the
Houston area.
BBQ - a hobby?
First, it’s not that unusual in
Houston to cook BBQ (over 300
restaurants) and second it’s down
right popular as there are over 800
BBQ teams in the greater Houston
area. A BBQ team is usually made
up of a BBQ Pit, a ‘head cook”,
and three to a hundred helpers.
You might wonder how a hundred
could actually cook, well they don’t
actually but the logistics for a BBQ
Cook-off Competition for a corporate sponsored team needs a big
group.
Biography
Benton Vandiver III received his BSEE from the University of
Houston in 1979.
He was with Houston Lighting & Power for 15 years and Multilin
Corp. for 4 years before joining OMICRON electronics where
he is currently Technical Director in Houston, TX. A Professional
Engineer, IEEE Member, and an active Z Krewe member (Galveston
Mardi Gras krewe), he mainly enjoys spending time with his wife
Julia and 2 year old daughter Jaclyn at every opportunity.
PAC.SPRING.2008
A competition, you ask?
Yes, that is one of the driving
forces for the popularity of BBQ
in the state of Texas, plus the fun
of participation. One guy says he
can make the best tasting BBQ, and
then someone else throws down
the challenge. Next they each tell
two friends and well, you know
the rest. They set the time and place
and all of a sudden you have a BBQ
Cook-Off!
These have become so popular
over the years that they are used
most often for charity fund raisers
and there’s an official organization
that oversees the competitions, it’s
the International Barbeque Cookers
Association. (www.ibcabbq.org)
The Houston Livestock Show &
Rodeo, (www.hlsr.com or http://
www.hlsr.com/et/bbqc/bbqc_index.aspx) is where they also host
one the largest BBQ competitions
in the state.
In 2008 the over 400 BBQ
teams competed over two days and
fed over 190,000 people coming
to the cook-off & rodeo event. The
amount of beef, chicken, pork, ribs,
and other items that were cooked
and consumed was staggering.
95
So how did I end up on a
BBQ team?
A close friend of ours asked
for help about ten years ago when
two of his team members (his sister & her husband) could not help
out. Julia and I said, “sure we’d be
glad too, what time do you need us,
where, and do I need to bring my Hibachi?” (a very small grill)
He replied, ”Be at Sam’s Grill &
Bar parking lot on Friday at 3pm,
we’ll be finished about 2pm on Sunday. And here’s a picture of the ‘Pit’
we’ll use to cook on.” (see Figure 4)
BBQ organization:
I first thought "what have I committed too?" Turns out a traditional
BBQ Cook-Off requires a while to
organize and execute.
The BBQ pit has to come up
to temperature.
The fresh meats of each team
have to be inspected and tagged
by the judges to insure fairness in
the competition, and it often takes
twelve to fifteen hours to slow
smoke a typical ten pound beef
brisket till it’s done and ready to be
served. (Ribs take five to six hours,
chicken takes three to four hours.)
So the whole process becomes
a forty-eight hour project management effort to coordinate the cooking of the four typical categories
(sometimes as many as seven categories) and have them at their tasty
perfection precisely on the hour
each one is required for submission
to the judges.
And yes, this means all teams
that are in the competition are doing the same thing.
So the larger the BBQ Cook-Off,
the larger the logistics for the panel
of judges to taste each team’s submission and come to a decision on
who’s is the best!
Once we participated in the first
cook-off, we were hooked and enjoyed each opportunity to help the
team. It’s actually hot hard work
but you get used to it because it’s
focused. You have a specific goal
and known time to get it completed. But at the same time there’s
down time where you can visit and
socialize with a great group of people with whom you build lasting
relationships.
Over a few years our team deve­
loped into an efficient workgroup
where each person knew their tasks
2 Some of the Coyote Cookers' awards for the
four years of competitions
The
BBQ team sign!
and performed them like clockwork. Of course we had to have a
team name, and ours was “Coyote
Cookers”. (see CoyoteSign above)
And in short order we had a run of
success over a few years where we
scored First Place in each category.
(see awards in Figure 2)
We were lucky enough to pull
it all together in a couple of competitions and place high enough to
be the overall team winner twice.
But the most memorable thing was
our tag line, “We eat the best and
submit the rest!” It was our way
of saying that we couldn’t resist our
own cooking and just couldn’t give
it to the judges.
Many of the other teams agreed
and we’d often have a large group
over when the meats came off the
pit. Our seven foot long pit was by
no means large; some pits can be as
big as an entire eighteen wheeler
(over 38 feet long), but it’s enough
to cook 14 briskets, 24 whole chi­
ckens, 16 full slabs of ribs, and even
a few pork loins. That’s enough to
feed a group of 300 people when
you add in the sides, like cole slaw,
potato salad and ranch beans.
Later Developments
About 4 years ago the team retired, mainly because our “head
cook” took this all way too seriously and opened a very successful
PAC.SPRING.2008
The Art of BBQ Cooking
hobby
96
BBQ catering business in Houston.
So successful he “retired” from his
day job and within six months was
financially secure.
So there was something to our
tag line and many in the Houston
area benefited from the years of
practice in those BBQ cook-offs. Julia & I also came away with a lot of
knowledge about cooking this way
and what really made great BBQ.
Our favorite was and still is
the BBQ Baby Back Ribs. (see Pit_
wRibs in Figure 3) These were so
good we would often cook up extras to take home after the cook-off
and feast for days. Then it wouldn’t
be long before we were eagerly anticipating the next cook-off date.
We still see the old team from
time to time and fire up the pit to
relive those great weekends.
I learned that the old adage,
“Good things come to those who
wait” has a lot of truth to it.
For really good BBQ you have
to be patient. If you are really patient, you can learn a few cooking
secrets. Each team develops their
own style, but almost all do these as
a minimum.
The Secret!
Here’s THE cooking secret for
great BBQ anything.
Get a Pit with a separate fire
box.
Use real wood: oak for heat,
mesquite or hickory for its flavor,
and Sassafras (or Cinnamon wood)
for a great natural BBQ taste.
Keep the temperature between 275 F and 350 F, 300 F being optimum.
Make sure you’re producing
enough smoke and never let flame
touch the meat.
If you follow those guidelines,
you can “BBQ” anything. Meats,
fish, foul and even vegetables.
If you have a traditional BBQ
with charcoal or propane, then fire
up one side to 350 F and cook on
the no fire side.
Use water soaked hickory wood
chips if possible to help create some
smoke, but indirect heat is better
than you think.
Recipes for almost anything can
be found on the web nowadays.
Google “Texas BBQ Recipes” for
some great sites and tips on Texas
BBQ.
3 Famous "Coyote" barbeque ribs
My motive
for joining the
barbeque team was
mainly for
entertainment,
but the good food
could be a reason
for staying nine years
with the Coyote
Cookers.
The Final Secret:
"Rub" is the term for the spices
applied to the meats, it can be either wet or dry. Both can yield excellent results. But it takes patience
and experimentation to find that
magic mixture that makes for a 1st
Place Winner!
4 The Coyote Cooker when new
Barbeque pits use indirect heat & smoke for
BBQ - the Texas way.
Try one of the recipes,
you will enjoy it!
A Quality Pit of this type ranges from $3000 - $5000 USD.
PAC.SPRING.2008
97
Here’s one of my favorites:
BBQ Whole Chicken
Prepare a fresh whole chicken by cleaning it thoroughly removing
all internals, loose skin and loose fat, then washing it in cold water.
Pat it down with a paper towel but leave it moist.
Then dry season it the way you normally like.
As a suggestion: in a bowl, combine 3 tablespoons of black pepper, 1 teaspoon of garlic salt, 1 teaspoon of cayenne pepper and 2 tablespoons of any Italian seasoning. (Adjust ratios to taste if this is too strong
for your pallet.) Mix thoroughly and then pat over entire outside of
chicken. (we called this loving the chicken)
Take any remaining mix and shake inside the chicken to coat it.
Now you need a canned beer, (no glass) we used Miller Lite or Bud
Light because we really want the water content, but I’ve used dark beers
like a Guinness with good results too.
Open the beer and carefully shove it up the opening in the chicken
(yes that’s it’s a$$) so that the chicken will “stand up” with the aid of
the can.
Place it carefully on the grill and close the grill’s lid.
Check it after 15-20 minutes and make sure it stays standing, the
beer will come to a slow boil and keeps the chicken moist from the
inside.
Using indirect heat it will take about 2 hours to cook.
During the process you can “glaze” the chicken with a BBQ sauce
if you wish but it really isn’t necessary.
Practice a few times and you’ll find it makes a terrific entrée and a
conversation piece when entertaining your friends.
We eat the
best
and submit
the rest!
Coyote
Cookers
1996-2005
5 BBQ whole chicken - one of Benton's favorites
If you or one of your
colleagues has an interesting
hobby, please let us know.
Send an e-mail with a brief
description to:
editor@pacw.org
PAC.SPRING.2008
last word
98
Your Opinion
Every quarter we post a question on
the PAC World web site and ask you
to select an answer that will help your
colleagues from around the world understand the trends in our industry.
No clear preference
For three months we had on the PAC
World web site a simple question:
What redundant protection do you
use on transmission lines?
What redundant protection do you use on transmission lines?
The results from this non-scientific
poll are shown in the chart to the
right. As in the previous survey
the number of people that decided
to pick one of the four answers is
relatively small – 166. I would like
once again to say that it is not that
difficult to take part in it, while
by clicking on an answer that you
select you will make an important
contribution to our understanding
of industry practices.
If we analyze the result it is clear
that one thirds of the participants
prefer to use both relays of the same
type and same manufacturer. The
remaining three options are evenly
distributed – at about 20% each.
This is probably due to the fact
that the decision for selection
of redundant transmission line
protection relays are based on many
different factors, such as economics,
training, maintenance, protection
philosophy, etc.
The new question on the web site
is related to the main subject of the
Spring 2008 issue – power systems
analysis:
What type analysis tools do you use
related to protection and control?
The answers that you can choose
from are:
Short circuit and protection
coordination,
Electromagnetic transient
simulation,
Both ,
None.
Please take a minute, go to the web
site page and click on your choice.
— Alex Apostolov
calendar
The answers to the questions you can
choose from and the percentage of
responders that selected them are as
follows:
Same type and same manufacturer:
34.9%
S ame t ype and different
manufacturer: 23.5%
Different t ype and same
manufacturer: 21.1%
Different type and different
manufacturer: 20.5%
Poll Results:
IX Spanish-American
Electric Power Systems
Protection Symposium
20-23 May 2008
Monterrey, México,
http://www.uanl-die.net/
pages/sipsep.html
WINDPOWER 2008
Conference & Exhibition
1 - 4 June 2008
Houston, Texas
http://www.
windpowerexpo.org/
PAC.SPRING.2008
IX Technical Seminar on
Protection and Control
1 - 5 June 2008
Belo Horizonte-MG,
Brazil
http://www.ixstpc.com.br/
paginas/default.asp
8th West African mining
and power exhibition and
conference 2008
3-5 June 2008
Accra, Ghana
http://ems.mbendi.com/
events/e4zj.htm
POWERGRID Europe
3 - 5 June 2008
Milan, Italy
http://pgrid08.events.
pennnet.com/fl/home.
cfm?Language=Engl
EAA 2008
14–15 June 2008
Christchurch,
New-Zealand
SmartGrids for
Distribution seminar
23 - 24 June 2008
Frankfurt, Germany
http://conferences.theiet.
org/ciredsmartgrids/index.
htm
IEEE RVP AI
6 - 12 July 2008
Acapulco, Mexico
2008 IEEE PES General
Meeting
20-24 July 2008
Pittsburgh, PA, USA
http://ewh.ieee.org/cmte/
PESGM08/
ACS Applied Control
Systems Cyber Security
Conference
4-7 August 2008
Chicago, IL , USA
http://realtimeacs.
com/?page_id=18
T&D Latin America
13-15 August 2008
Bogota, Columbia
http://www.ieee.org.co/
tydla2008/
CIGRE Session 2008
24-29 August 2008
Paris, France
http://conferences.theiet.
org/ciredsmartgrids/index.
htm