Adding Intelligence to
Substations and Distribution Lines
Gerrit Dogger
Cybectec Product and Application Specialist
Cooper Power Systems
Gerrit.dogger@cybectec.com
HU
U
Canada
Summary
The emergence of new technologies allows utilities to
improve their electric networks’ reliability, handle
emergency situations and increase the value of
available data. This paper discusses the power industry
trend towards decentralized automation capabilities,
which is accomplished by merging available
equipment with new technologies without having to
change the substation control systems.
Most substations are now equipped with a data
concentrator, also known as a gateway. The gateway is
used to supply data to the control center, and to handle
commands received from the control center. The
gateway’s processing power and its advanced
communications capabilities increase efficiency and
reliability significantly, making decentralized
automation more and more widespread. This paper
presents three case studies that demonstrate how.
The first case study takes a look at the emergency load
restoration process in a substation of a petrochemical
plant. In this case, the gateway was installed in the
substation for data concentration, protocol translation
and remote control. By using the gateway, no
additional hardware was required to create the feeders’
and emergency generators’ complex control logic.
The second case shows how the gateway can increase
efficiency by using its embedded intelligence to
calculate statistics based on real-time data. In recently
built wind parks of the Quebec province, gateways
were deployed to meet Hydro Québec’s requirements
for data acquisition and processing. By performing
calculations locally rather than at the remote control
center, a large amount of the real-time data was no
longer required outside the wind parks, reducing the
bandwidth usage for data transmission to the control
center.
The final case is related to a stand-alone distribution
system that uses automatic power source control to
improve power reliability in a specific part of the
electric grid. An industrial client of a utility was
concerned with the duration of power outages, which
could result in the solidification of the plastics in their
production line. A small gateway was installed to
gather source availability information and to control
reclosers, switching from the main source of power to
an alternate one in case of outage.
Keywords
Automation
Gateway
Data concentrator
Distributed intelligence
Introduction
Modern substations and distribution installations use
data concentrators and gateways to create the link
between substation equipment and the control center.
Most of these gateways have the processing power and
capabilities to implement automation functions. This,
in combination with the availability of all substation
data in a single device, enables the possibility of
substation wide automation. It is not limited to control
automation: , The gateway’s available computing
power allows the generation and calculation of
Presented at GCC CIGRE Power 2008, 10-12 November, Manama - Bahrein
All these principles and advantages apply on a smaller
scale. Even if gateways are mostly used in medium or
large size installations, smaller gateways with
automation capabilities can be used to implement
standalone pole top applications.
additional data, such as statistical values like the
average and standard deviation of the running values.
The advantages of distributed intelligence using data
concentrators are multiple. As it allows some
intelligence to be implemented in the substation, a
gateway optimizes the architecture of the substation,
reducing the complexity of the remote control center
and its communications infrastructure. Moreover, the
required communications bandwidth usage can be
reduced considerably if only the locally processed and
calculated data is transferred to the control center. All
of this is achieved using the existing already installed
hardware. This leads to the indirect advantage that less
wiring is required, as the switch yard is already wired
to the IEDs that supply the information to the gateway.
This paper will discuss three real-world case studies to
highlight the different possibilities of automation:
• Emergency load restoration in a
petrochemical plant.
• Real-time statistical data calculations in a
wind farm.
• Pole top automation to improve reliability.
Incomer #1
Incomer #2
EDG #1
EDG #2
EDG #3
52R-2
52L-3
52L-2
52L-1
52R-1
52L-R
NO
F1
F2
F16
F17
Figure 1: Substation single-line diagram overview
An overview of the substation can be seen in Figure 1.
A total plant blackout is defined as an undervoltage
trip on both incomer lines.
X
Case Study 1: Emergency
Load Restoration
X
The substation architecture is shown in Figure 2. In
this figure, we see the redundant control centers, the
redundant gateways, the emergency diesel generator
(EDG) breaker IEDs, the incomer undervoltage PLCs,
an emergency diesel generator control unit, and the
feeder IEDs.
At the refinery of the CNOOC-Shell joint venture in
Nanhai (China), the intelligent gateway-IED
architecture is used to automatically re-establish the
refinery’s most important power loads (for example,
chemical cooling equipment) in case of a complete
plant blackout.
X
-2-
X
Redundant control center
Redundant gateways
EDG
CU
Incomer
undervoltage
PLCs
Generator
breaker IEDs
Feeder IEDs
Figure 2: Substation architecture
The following logic is handled by the intelligent
redundant gateways:
1.
2.
The two circuit breakers (52L-3 and 52R-2)
on corresponding incomer lines are tripped
open by the undervoltage relays.
On reception of the two undervoltage trip
signals, which are hardwired from 2x 6KV
incomers, the master controller of the
emergency generator starts the run-up
sequences of the three emergency diesel
generators.
3.
Still on reception of the two undervoltage trip
signals, the gateway’s automation component
starts to trip all seventeen transformers, and
the bus tie-breaker is closed by the EDG CU.
4.
When all outgoing feeders are open and the
load on the 6kV emergency bus is less then 1
MW, the gateway’s automation component
sets the “Permissive to sync and close EDG’s
CB” signal to 1.
5.
If the “Permissive to sync and close EDG’s
CB” does not reach the EDG MCP due to a
fault, either on on the gateway, the
automation function or the MODBUS RTU
link, then the EDG MCP closes EDG
generator breakers after a few seconds delay.
6.
Whichever emergency generator runs up first
has its corresponding breaker closed on the
dead bus.
7.
When the second generator runs up, its
corresponding breaker is closed via autosynchronization between the bus and the
generator.
8.
Similarly, when the third emergency
generator runs up, its corresponding breaker is
closed via auto-synchronization.
9.
The gateway receives the breaker`s closed
status from the available emergency generator
breaker IED. The gateway’s automation
component then initiates the closing of the
transformer feeders’ circuit breakers based on
control center operator-defined priority and
available generated power. The available
generated power is computed based on the
number of emergency generator breakers that
are in the closed position.
The implemented solution is a straightforward state
machine program that follows that logic, as depicted in
Figure 3.
X
-3-
reason and should not be closed
automatically.
Remarks:
D) No immediate check is performed to make
sure that a feeder closed correctly; rather,
there is a general retry mechanism for all
feeders that did not close due to whatever
error (communications problem, absence of
power on the close coil, etc.). This is done to
reduce the total restoration time.
A) If all feeders are opened, the state machine
bypasses the “Wait for feeders to open” state.
This way, in the case of a failover, the feeders
are not reopened again.
B) Power is not actually calculated: it is assumed
that each generator supplies 2 MW. The
whole system is designed such that only 2
generators are required for complete power
supply.
E) When the incomer lines are restored, the
operators can put the automation program into
“IDLE” state without closing the remaining
feeders.
C) The “Determine next feeder” action selects
the next feeder to close based on priority.
However, for operational safety, feeders that
were opened at the start of this process will
not be closed. The idea behind this is that
those feeders were surely opened for a good
The whole system was commissioned in November
2005 to the complete satisfaction of CNOOC-Shell.
Under normal conditions, it takes less than 1 minute to
execute the complete restoration process.
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Start state
C: Start of SMP
A: Initialize system
C: One or both incomers closed &
C: `Permissive to syn and close EDG`s CBs`
A: Reset `Permissive to syn and close EDG`s CBs
IDLE
C: Both incomers open &
C: NOT `Permissive to syn and close EDG`s CBs`
A: Open feeders
C: Both incomers open &
C: `Permissive to syn and close EDG`s CBs`
Wait for feeders to
open
C: One or both incomers closed
C: (Both incomers open &
C: All feeders open &
C: Bus load less than 1 MW) OR
C: FeederOpenTimer timout (10 sec)
A: Set `Permissive to syn and close EDG`s CBs
Wait for power
from generators
C: One or both incomers closed
C: 1 or more EDG`s CB s closed
A: Calculate power
A: Determine next feeder
C: All feeders Done &
C: Retrycounter < 3
A: Retrycounter := Retrycounter + 1
C: One or both incomers closed
Closing feeders
C: Power is available
A: Calculate power
A: Close selected feeder
Determine Close
Fail
C: (Feeder is closed || timeout (5sec)) &
C: Not all feeder are closed
A: Determine next feeder
Wait for close
confirmation
C: Feeders to retry deteminated
A: Determine next feeder
C: One or both incomers closed
Figure 3: Emergency load restoration process` state machine
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Case Study 2: Real-Time
Statistical Data Calculations
Wind parks are installed throughout the province and
can be located up to 1,000 kilometers from the central
data center. To reduce communications bandwidth
requirements, Hydro-Québec requires that wind farm
owners supply them statistical data on a 10 minute
basis. The data to be supplied is the 10 minute
minimum, maximum, average and standard deviation
of each turbine’s wind speed, wind direction, turbine
direction, blade position and produced power. As well
as statistical information of other park values such as
available turbines, total power production.
Integration of wind parks in an electric grid is not an
easy task, as the produced power is variable by nature.
As the development of wind farms in the province of
Québec is strongly growing, Hydro-Québec (a
production, transmission and distribution utility in the
province of Quebec, Canada) must be able to better
predict the power production per park. For that matter,
it must gathers all type of data from each turbine in the
wind park such as wind speed, wind direction, blade
and turbine orientation. Besides the individual turbine
information, some general park information is also
required, such as the park’s total power production.
Hydro–Québec’s production planning center uses wind
park data for correlation of the production with other
environmental information. In the future, the
combination of multiyear statistical production data
and weather forecasts would allow more precise
production prediction, thus allowing better production
planning for the whole province grid.
The following figure illustrates the simplified wind
park architecture. The data from the turbines is
gathered by the turbine`s data server, and is than made
available via OPC. Data from the meteorological
tower(s) is gathered by radio links using Modbus.
Switchgear interfacing is handled by the protection
relays and the substation RTU: this information is
made available via DNP3. All gathered information is
then concentrated into the SMP Gateway.
Fiber optic connections for data
communications to turbine server
Substation building
Meteorological
measurements
Substation
Substation RTU
protection relays
Radio
communications
Turbine data server
Substation network
Ethernet communications
link to Hydro-Québec
Figure 4: Simplified wind farm communication architecture
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Within the SMP Gateway, additional logic is executed,
using the available IEC 61131-3 Soft-PLC component.
It will determine the minimum and maximum values,
as well as the average values and standard deviations
for each 10-minute period. At the end of this period,
the gathered values are sent to Hydro-Québec for data
storage.
Case Study 3: Pole Top
Automation
The third case discusses the use of automation logic to
improve power distribution. In Fort Wayne, Indiana
(USA), part of a distribution line is located
underground. For several reasons, this part of the line
is prone to interruptions. These interruptions are
causing economic losses to the connected industrial
clients, especially a plastics plant where the production
line gets solidified when there is a power outage for
more than 10 minutes. These problems put pressure on
the utility to implement a solution to improve the
reliability of its distribution network. Figure 5 presents
an overview of the solution that was proposed by
Cooper Power Systems.
The first system was deployed in the summer of 2007,
followed by a second system in the autumn of 2007.
After these successful installations, Hydro Québec
adopted the Cooper Power Systems’ Cybectec SMP
Gateway as the standard gateway for wind farms’ data
calculations and communications. Therefore, all new
and existing wind farms need to implement the
SMP Gateway as the data bridge to the Hydro Québec
network. Other installations are already foreseen in
2008 and with recent announcements regarding new
wind farms being built, more installations will follow.
X
Alternate site
Normally Open
X
Main site
Normally Closed
Substation
S2
Underground
cables
Substation
S1
900MHZ
Radio
Serial link
to radio
Serial link to
Form6
Figure 5: Pole top automation overview
infrastructure. This survey identified two possible
problems:
1. There was no direct line of sight between the
two selected installation locations.
2. The location of the main site was 40 feet
lower than the alternate site
The solution was to install controllable reclosers at
strategic sites besides feeder lines, together with a data
concentrator. These sites are called the main site and
the alternate site. The data concentrator at the main site
will gather the information from the recloser
controllers, and implements logic to open and close the
reclosers based on the detection of the absence of
source voltage at the main site. The proposed solution
also planned an automatic switch of power back from
the alternate site to the main site, when power would
return to the main site.. After discussions with the
client and for safety reasons, this feature was replaced
by an option that let the operator initiate the return-tonormal situation using one of the available buttons on
the recloser controller.
To overcome these problems, the corresponding
measures were taken:
1. A radio repeater was installed between the
main site and the alternate site, at a location
called the repeater site. This site was located
to have direct lines of sight with both the
main and alternate sites.
2. A 60-feet pole was installed at the main site to
bring the antenna at the same level as the
repeater and alternate sites.
The communications link from the data concentrator to
the alternate site is done through unlicensed 900 Mhz
radios. To select the correct radio equipment, a site
survey was held before finalizing the communications
As in the second case study, the gateway’s available
standard IEC 61131-3 Soft-PLC component was used
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The complete system was installed and commissioned
during the summer of 2008.
to implement the required logic. This logic is based on
the “break before make” algorithm, and the resulting
state machine is presented in Figure 6.
X
X
INIT
AST READY && R1.ASTLED && R2.ASTLED
NORMAL
NOT AST READY
Loss of voltage R1 X secondes AND
R2 Voltage AND AST READY
Open R1; Retry = 0
Timeout AND Retry < MaxRetry
Open R1
Wait open
R1
NOT AST READY
Timeout AND Retry < MaxRetry
Close R2
R1 open
Close R2; Retry = 0
Wait close
R2
NOT AST READY
NOT AST READY
Command Return to Normal
Command Return to Normal
R2 closed
Wait
Manual
Restore
Command Return to Normal
OR (R1 Closed AND R2 Open)
R1.ASTReturn OR R2.ASTReturn OR
Force return web command
Open R2; Retry = 0
Timeout AND Retry < MaxRetry
Open R2
Wait open
R2
R2 open
Close R1; Retry = 0
NOT AST READY
Timeout AND Retry < MaxRetry
Close R1
Command Return to Normal
Wait close
R1
NOT AST READY
Command Return to Normal
R1 closed
Figure 6: Automatic source transfer process’ state machine
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Conclusion
The technology and solutions presented in this
document are now available as off the shelf products
and have been tested, installed and commissioned for
the discussed range of solutions.
The above case studies showed that added intelligence
in data concentrators can be used in a large variety of
situations. Using this data locally helped to implement
automatic power restoration, or to improve power
reliability. But the advantages are not limited to this:
by using appropriate algorithms, additional data can be
calculated on-site, thus directly adding value to the
available system, while at the same time reducing
communications requirements.
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