North
N
th A
American
i
SynchroPhasor Initiative
Working Group Meeting
March 6 & 7, 2008
The role of Phasor Data Concentrators
(PDC requirements for Large Scale
Applications)
Presentation outline
• Introduction
• The information produced by C37.118
– Different
Diff
t levels
l
l off concentration
t ti
– The impact of the volume of information
• Typical on-going projects for PDC’s
– Data storage and off-line analysis
– Data concentration
– Data concentration with decision capabilities
Presentation outline (cont’d)
(cont d)
• Where is the best breakpoint for a PDC to
a « Super PDC »
• Is the ultimate goal control with this
information?
– If yes, from
f
where
h
would
ld b
be th
the b
bestt llevell ffor
the control or is it at multiple levels?
Introduction
• For the purpose of this discussion all
sampling is performed at 60 times per
second (that has been a request from a
number of utilities in the past year)!
• Question: Is this a new trend seen by
NASPI going
i ffrom 30 tto 60 samples
l per
second?
The information by C37
C37.118
118
The following slides provide a quick review
of C37.118
C37 118 data structures
structures.
IEEE C37.118
C37 118 Standard
•
No.
1
2
3
4
5
6
7
8
9
10
11
12+
Data from a PMU to a PDC
Field
SYNC
FRAMESIZE
IDCODE
SOC
FRACSEC
STAT
PHASORS
FREQ
DFREQ
ANALOG
DIGITAL
CHK
Size
2
2
2
4
4
2
4x6
2
2
0
0
2
Description
Synch byte
# of bytes in frame
ID
SOC time stamp (of the PMU)
Fraction of second (of the PMU) and quality
Bitmapped flags
g
6 substation direct sequence voltage phasors
Substation frequency
Rate of change of frequency
Not used
Not used
CRC-CCITT
Bandwidth Requirements per PMU
• At 60 frames/second
– 48 bytes * 60 = 2,880 bytes/second or
approximately 30,000
30 000 bits per second (not to
much for a one connection)
• Or with 50 PMUs sending data to a PDC
– Combined data rate of 144,000 bytes per
second or approximately 1
1,440,000
440 000 bits per
second (starting to be interesting for a
connection)
IEEE C37.118
C37 118 Standard
•
Data from a PDC to a Higher Level System
No.
No
1
2
3
4
5
6
7
8
9
10
Field
SYNC
FRAMESIZE
IDCODE
CO
SOC
FRACSEC
STAT
PHASORS
FREQ
DFREQ
ANALOG
11
12+
DIGITAL
CHK
Size
2
2
2
4
4
2
4x50
2
2
4x50
4x2
2x1
2
Description
Synch byte
# of bytes in frame
ID
SOC time stamp (of the PMU)
Fraction of second (of the PMU) and quality
Bitmapped flags
Direct sequence voltage phasors of 50 PMUs
Not used
Not used
Load Voltage,
Voltage Deltaθ,
Deltaθ Delta f
Packet transmission time: SOC+FRACSEC
PMUs used for Deltaθ, Delta f computations
CRC-CCITT
Bandwidth Requirements per PDC
to higher
hi h llevell system
• At 60 frames/second
– 424 bytes * 60 = 25,440 bytes/second or
254 400 bits per second)
254,400
• With 10 PDC’s sending information at 60
frames/second
– 25,440 bytes * 10 = 2,544,000 bytes/second
In a wide area environment
IEEE C37.118
C37 118 Standard
•
What would be the requirements of a “Super”
PDC
–
–
–
The « Super PDC » can be thought of an
enterprise level system capable of receiving
massive amounts of data (many hundreds of
PMU’s or maybe thousands, what should it be?).
Store this vast amount of information produced
by all these PDC’s or maybe PMU’s.
Allow multiple distributed systems to access the
current information plus the older data for
analysis.
Typical on-going
on going projects
The following slides will present work we
are doing with different utilities in the area
of Phasor data concentrators.
Low level PDC’s
PDC s
• Used for local storage and off-line
off line analysis of
small amount of PMU’s.
• Normallyy with limited amount of storage
g ( 6 to 12
months)
provides local visualization in real-time
• Normallyy p
with viewing screens for the historical
information.
• Quite often the first step for a utility who is
looking at how to use this type of information.
PMU Data Concentration
• Normally the next step for a utility in
working with Phasor data.
– Concentrate the data
data, in this case from many
PMU’s and/or PDC’s together.
– Store the information for a longer period of
time to allow more in-depth analysis in the
interaction of the overall data.
PDC with Decision capability
• When utilities feel they have reached a
level of confidence and understanding of
the capabilities of this technology
technology, senior
management will normally go to the next
step and allow control functions to be
activated by PDC’s.
Control Aspects with a PDC
The next slide provides a diagram of a
system whose goal is to control equipment
to stabilize the grid for a large metropolitan
area.
area
Control Aspects of a PDC
The Control Action by the PDC
• Once a decision is taken by the logic
logic, the
control objective is simple!
• What would be the best way to document
the overall control trigger process?
– General
G
l llog off diff
differentt events
t
– A configurable time before and after the event
to record the principal information (and store
in Comtrade format or other format)?
The Ultimate Goal (discussion)
• The goal in reading all this information is
for control?
• But what kind of responses are we looking
at going through all these systems, will the
control be timely (this discussions to be
based on having PDC’s in the Sub, and at
an intermediate level and at a Super
level)?
The Ultimate Goal (discussion)
cont’d
’d
• Using the capabilities of advanced
intelligent PDC’s to work in a distributed
decision making environment
environment, can we
achieve acceptable control?
– This context is based on having level 2 PDC’s
PDC s
capable of making decisions but also talk
((61850 or other p
protocols)) to a number of
other PDC’s at its level or receiving new
settings from a higher level system.
Discussion – Question Period
The goal of this presentation is to create a
discussion of where we are going.
What are the next requirements in making
thi d
this
dream h
happen – i.e.
i h
having
i a stable
t bl
electrical grid by using the Phasor
i f
information
ti iin a manageable
bl ffashion.
hi
Thank You!
Robert
R
b t O’ R
Reilly
ill
Senior Application Engineer
Cooper Power Systems –
Energy Automation Solutions