1 Tele-Seminar, April 30, 2004 PSERC April 30, 2004 PSERC Tele-Seminar April 30, 2004 PSERC Tele-Seminar Role of GPS Synchronized Measurements in Power System Visibility Role of GPS Synchronized Measurements in Power System Visibility Sakis Meliopoulos Georgia Tech Sakis Meliopoulos Georgia Tech
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1Tele-Seminar, April 30, 2004PSERC
April 30, 2004PSERC Tele-Seminar
April 30, 2004PSERC Tele-Seminar
Role of GPS Synchronized Measurements in Power System Visibility
Role of GPS Synchronized Measurements in Power System Visibility
Sakis MeliopoulosGeorgia Tech
Sakis MeliopoulosGeorgia Tech
2Tele-Seminar, April 30, 2004PSERC
Outline
• Power System Visibility (Real Time Model)
• GPS Synchronized Measurement Technology
• Data Validation – Issues
• NYPA’s HMS
• Hybrid State Estimator
• Numerical Experiments
3Tele-Seminar, April 30, 2004PSERC
Recommendation 22Evaluate and adopt better real-time tools for operators and reliability coordinators.
• New Enhancement:WAAS (Wide Area Augmentation System)Performance Much Better
• Other Enhancements in the Works…
6Tele-Seminar, April 30, 2004PSERC
GPS-Synchronized Measurements
• Technology Became Available to Power Systems About 15 years ago
• Specialized Equipment
• Addition of GPS Synchronization in IDEs and Relays
• Cost is Rapidly Reducing (Basic Receiver is $30)
• Technology is Under-Utilized
7Tele-Seminar, April 30, 2004PSERC
IED Cordova
IED West Point
IED VolunteerIED Johnsonville Fossil Plant
IED Kanawha River
IED Callaway, Ameren
IED Rockport, AEP
IED Rush Island, Ameren
ECARMAIN
IED Jacksons Ferry, 765 kV
IED Orange, AEP
Planned GPS-Synchronized Measurements for the TVA System
8Tele-Seminar, April 30, 2004PSERC
2 2
1
2
239
62
4
1
9067
5
43
24
10
82
24515
840
19
4
2
Courtesy of SELCourtesy of SEL
SEL-421 Deployment Eastern USA
9Tele-Seminar, April 30, 2004PSERC
By Virtue of its Timing Accuracy the Technology Can Be Used to Directly Measure the State of the Power System
GPS-Synchronized Measurements
10Tele-Seminar, April 30, 2004PSERC
Measurement ErrorsGPS Synchronized Measurements are More Accurate than Sensors but still Imperfect – Errors are PresentSensorless SCADA Have Accuracy Comparable to GPS Synchronized Measurements
System Exhibits “Internal” ErrorsErrors from InstrumentationErrors from ImbalanceErrors from Asymmetry
SolutionData Filtering via Estimation Methods Validation
Important Observations
11Tele-Seminar, April 30, 2004PSERC
RS232Ethernet and RS232Communications0.01 Degrees0.01 DegreesPhase Measurement Error at 60 Hz
Power System SE: Basic Assumptions• Positive Sequence Model• P, Q, V measurement set• Instrumentation Errors Part of Meas Data• Near-Simultaneous Measurements• Single Frequency
Implications:• Balanced Operation• Symmetric Power System• Biased SE• Iterative Algorithm
Traditional State Estimation
19Tele-Seminar, April 30, 2004PSERC
NYPA’s Harmonic Measurement System Using GPS Synchronized Measurements (Macrodyne’s PMUs)
I
Global TimeReference
(GPS)
GPSReceiver
MicroprocessorA/D
Phasor data(time stamped)SerialCommunicationPort
Filte
r
To Control Center
Harmonics DataConcentrator
(Located in Atlanta)
PMU Block Diagram
V
GPS Antena
ADD BulletinBoard System
GIC DataConcentrator
Located at NYPP
PMUComputer
PMUComputer
PMUComputerHMS Host System
Massena
Marcy
Niagara
Fraser
Robinson PTS
PTS
Albany
Coopers Corner
1 2
PTS
PTS
PTS
PTS
PTS
MASENA765
MARCY765
NIAGARA ROBINSON
EDIC
MARCY345
NSCOTLAND
VOLNEY
FRASER
COOPERSC
CLAY MARCY-T1MARCY-T2
OAKDALE
GILBOA
FRASER115
ROB115ROB-T1
STOLLE
HINMAN
LOCUST
HARISON
NIAG230
NIAG-T1
NIAG-T2
NR-2 PA-301PA-302
MASNA230BMASNA-T1
MASNA230AMASNA-T2
MOSES230
MMS2
CHTAUG765
LAFAYETTE
HMS Host SystemMassena
Marcy
Niagara
Fraser
Robinson PTS
PTS
Albany
Coopers Corner
1 2
PTS
PTS
PTS
PTS
PTS
MASENA765
MARCY765
NIAGARA ROBINSON
EDIC
MARCY345
NSCOTLAND
VOLNEY
FRASER
COOPERSC
CLAY MARCY-T1MARCY-T2
OAKDALE
GILBOA
FRASER115
ROB115ROB-T1
STOLLE
HINMAN
LOCUST
HARISON
NIAG230
NIAG-T1
NIAG-T2
NR-2 PA-301PA-302
MASNA230BMASNA-T1
MASNA230AMASNA-T2
MOSES230
MMS2
CHTAUG765
LAFAYETTE
Asymmetric Power System
ModelNew York Power
Authority
20Tele-Seminar, April 30, 2004PSERC
Synchronized Measurement Based SEWhat is the Advantage
va(t)ia(t)
vA(t)iA(t)
vb(t)ib(t)
vB(t)iB(t)
vc(t)ic(t)
vC(t)iC(t)
Voltage Waveform Measurement
Current Waveform Measurement
Bus 1 Bus 2
a
b
c
A
B
C
Phasor Measurements of Voltages and Currents
21Tele-Seminar, April 30, 2004PSERC
SE with Synchronized Measurements
* * * Direct Solution * * * * * * Direct Solution * * *
⎥⎦
⎤⎢⎣
⎡
−+
=⎥⎦
⎤⎢⎣
⎡⎥⎦
⎤⎢⎣
⎡− real
Timagimag
Treal
imagTimagreal
Treal
imag
real
WzHWzHWzHWzH
xx
ABBA
rWrMin H ~~
xHzrtoSubject ~~~~: −=
imagT
imagrealTreal WrrWrrMin +
imagimagrealrealrealreal xHxHzrtoSubject −−=:
realimagimagrealimagimag xHxHzr −−=
22Tele-Seminar, April 30, 2004PSERC
In Case that All Data are GPS Synchronized Measurements the
State Estimator is DIRECT
Big Advantage
Observation
23Tele-Seminar, April 30, 2004PSERC
24Tele-Seminar, April 30, 2004PSERC
Detection of SE Bias
Case Description Confidence Level(Chi-Square Test)
Three Phase Asymmetric Model,Three Phase Measurements
100.00
Three Phase Symmetric Model,Three Phase Measurements
13.02
Three Phase Asymmetric Model,Single Phase (A) Measurements
AC (AC Withstand) 1050.0 Transposed Phases Insulated Shields Transposed Shields
Program WinIGS-F - Form IGS_M102
31Tele-Seminar, April 30, 2004PSERC
QPF-SE Approach: Hybrid SE Formulation
∑∑−∈∈
+=synnonphasor
JMinν ν
νν
ν ν
νν
σηη
σηη
22
* ~~
νν η~~~~,, +−= NkAk VVz
ννν ηη ~
~~~~~~
~~
,
,
,
,
,
,
,,1,,1 +
⎥⎥⎥⎥⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢⎢⎢⎢⎢
⎣
⎡
=+=
Ck
Bm
Am
Ck
Bk
Ak
TAkdAkd
VVVVVV
CIz
=+−= νν η2~~ 2
,, NkAk VVz
ννν ηη +
⎪⎪⎪⎪
⎭
⎪⎪⎪⎪
⎬
⎫
⎪⎪⎪⎪
⎩
⎪⎪⎪⎪
⎨
⎧
⎟⎟⎟⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜⎜⎜⎜
⎝
⎛
⎥⎥⎥⎥⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢⎢⎢⎢⎢
⎣
⎡
=+=
*
,
,
,
,
,
,
,,1,,,1
~~~~~~
~Re
Ck
Bm
Am
Ck
Bk
Ak
TAkdAkAkd
VVVVVV
CVPz
GPS-Synchronized Measurements(Linear Model)
Non-Synchronized Measurements(Quadratic Model)
Voltage Phasor
Current Phasor Real Power
Voltage Magnitude
( ) ( ) νη22
,,,,2
,,,, +−+−= iNkiAkrNkrAk VVVV
32Tele-Seminar, April 30, 2004PSERC
Error of Bus Voltage Phase – Estimated minus Measured ValueMagnified 200 times (min error: -0.144, max error: 0.147 degrees)
33Tele-Seminar, April 30, 2004PSERC
Bad Data Detection & Identification
This is an Important Issue:
- Current Approaches are Computationally Demanding.- Leverage Points Are Especially Troublesome.
Utilizing All Available Data Increases Redundancy.
The implications are:(a) Increased Effort for System Initial Calibration, and (b) Improved Bad Data Identification Process.
Visualization Methods Also Help
34Tele-Seminar, April 30, 2004PSERC
Error of Bus Voltage Magnitude and Phase – Estimated minus Measured ValueMagnitude is Normalized (min magnitude error: 0, max magnitude error: 0.141)Phase is Magnified 200 times (min phase error: -0.672, max phase error: 0.165)
There is one bad DatumCan you find it?
There is one bad DatumCan you find it?
35Tele-Seminar, April 30, 2004PSERC
Error of Bus Voltage Magnitude and Phase – Estimated minus Measured ValueMagnitude Error Range: 0.1 to 4.4kV – Phase Error Range: -0.1 to 0.8 Degrees