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PMU simulation and application for power system stability monitoring
Harmeet Kang
Areva Technology Centre –
Stafford, UK
Sept. 2009 MOSCOW
2 2
Historical Perspective
Impossible to compare data from geographically different locations
No context to the measurements
Slow RTU data
Technology cost prohibitive
5 5
What is a Phasor
IEEE C37.118 specifies that the angle is 0 degrees when the maximum of the signal to be measured coincides with the GPS pulse and -90 degrees if the positive zero crossing coincides with the GPS pulse.
peak
1pps
Xr (n)
Xi (n)
6 6
Measurement
8 8
PMU device basics
GPSReceiver
Microprocessors
Oscillator
A/D
Analog
Digital
IEEE C 37 .118 DataElectrical
signal
Digitised Samples
Data Frame over Serial or Ethernet
(TCP /UDP )P847 PMU
Anti Aliasing
9 9
PMU device basics
GPSReceiver
Microprocessors
Oscillator
A/D
Analog
Digital
IEEE C 37 .118 DataElectrical
signal
Digitised Samples
Data Frame over Serial or Ethernet
(TCP /UDP )P847 PMU
Anti Aliasing
Phase delays /Variable
CT/VT
Mag/Angle Errors
Fixed delay in gathering data
Small error
Small error
10 10
GPS input
Time
Output Site 1
Light ON
Light OFF
Time
Output Site 2
Light ON
Light OFF
200ms+/- 1ms
<100 ns
Leading edge istiming point
12 12
Acceptable Total Vector Error (TVE)
Where Xr (n) and Xi (n) are the measured real and imaginary components and Xr and Xi are the reference values. This measurement accuracy varies with the magnitude and frequency of the input signal.
1% TVE ~ 0.5 degrees ~ 26 sec @60Hz
13 13
Measurement Window
Internal Reference
Measurement Window
GPS
Filter Coefficients are chosen to provide
A zero degrees phase shift if the middle of the window
corresponds to the peak of the signal
14 14
Filter Length
0
0.2
0.4
0.6
0.8
1
1.2
0 0.5 1 1.5 2 2.5 3 3.5 4
Harmonic
Gai
n
One Cycle
Three Cycles
Seven Cycles
Programmable
1 – 7 Cycles
Default - 5 Cycles
15 15
Impact of Filter Length
Noise Rejection
-60
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0 20 40 60 80 100
Frequency
Gain
(dB
)
1 Cycle
3 Cycles
7 Cycles
Particularly important to have good noise rejection
as inter area and local oscillations are around 0.1 -3 Hz
-1.5
-1
-0.5
0
0.5
1
1.5
0 0.2 0.4 0.6 0.8 1 1.2 1.4
50 Hz
50 Hz+5% 48 Hz.
17 17
PMU’s in a System
PMU1 PMU2
PMU3 PMU4
PDCE-terra
18 18
Phasor Data Transfer
19 19
IEEE C37.118 Protocol
Configuration => To PDC
Header =>To PDC
Data => To PDC
Command <= From PDC
27 27
PMU Locations and Number of
»Which feeders are key to the interconnection between grid regions
»Which nodes exhibit large shifts in power angle based on a loss of generation, load and change in topology.
»Which areas are of interest from a load modelling perspective
»Which areas of the grid are known to contain dynamic stability issues
»Which areas can form frequency Islands
»Which areas of the grid are prone to voltage collapse
»Which nodes will be most beneficial for the current state estimator improvement and a future linear state estimator
28 28
PMU Locations and Number of
Phenomena
Power Angle
Load Dynamics
Stability monitoring
Frequency Islands
Voltage Collapse
State Estimation
29 29
System Study and Virtual PMU’s
30 30
Application of PMU’s in Power System Stability
31 31
Small Signal Stability
Ability of a power system to maintain synchronism
When subjected to small disturbances.
In today’s practical power systems, the small signal
Stability problem is usually of insufficient damping
of system oscillations
Ref: Power System Stability and Control
Prabha Kundur
32 32
Small Signal Stability
0 5 10 15 20 25 30 35 402.02
0.01507
1.982.025
2.015
Y t( )
400 t
33 33
System Oscillations
Ref: UNDERSTANDING POWER SYSTEM STABILITY
Michael J. Basler and Richard C. Schaefer
34 34
Oscillations
f t( ) ed t sin b t( )
0 2 4 6 8 10 12 14 161
0
1
d>0
f t( )
t
d 0.5
f t( ) ed t sin b t( )
0 2 4 6 8 10 12 14 162000
0
2000
d<0
f t( )
t
Negative damping produces an unstable oscillation
36 36
Power Transfer Between Two Systems after a disturbance
37 37
38 38
PMU Data
39 39
Modal Analysis
-1
1
3
5
7
9
0.5 1 1.5 2 2.5 3
Freq (Hz)
Am
pli
tud
e /
Dam
pin
g
-25
-20
-15
-10
-5
0
5
10
15
20
25
Ph
ase(r
ad
)
Amplitude P
Damping P
Phase P
-1
1
3
5
7
9
0.5 1 1.5 2 2.5 3
Freq(Hz)
Am
pli
tud
e/D
am
pin
g
-25
-20
-15
-10
-5
0
5
10
15
20
25
Ph
ase(r
ad
)
Amplitude K
Damping K
Phase K
Oscillatory Modes and associated
damping factors for two buses in a
system after a small
disturbance
40 40
Frequency Mode Amplitude Damping Factor Phase
5.915093601 0.154921691 3.803229646 -0.56479
-5.915093601 0.154921691 3.803229646 0.564785
2.528276218 6.166677265 5.96187498 12.05712
-2.528276218 6.166677265 5.96187498 -12.0571
0.11361277 0.052975648 -0.243568244 -0.08402
-0.11361277 0.052975648 -0.243568244 0.084017
1.160329029 0.016464454 1.228181975 0.067127
-1.160329029 0.016464454 1.228181975 -0.06713
2.004414648 13.74912722 7.02501959 57.03535
-2.004414648 13.74912722 7.02501959 -57.0354
5.886455596 0.059326209 3.676118362 -0.39502
-5.886455596 0.059326209 3.676118362 0.395017
5.816091733 0.268517515 4.184619447 -0.7797
-5.816091733 0.268517515 4.184619447 0.779701
0.499234685 9.092862427 4.838452008 18.89328
-0.499234685 9.092862427 4.838452008 -18.8933
1.323992576 6.44246368 4.988312993 26.19057
-1.323992576 6.44246368 4.988312993 -26.1906
41 41
Significance of Negative Damping
-10
-8
-6
-4
-2
0
2
4
6
8
10
0 2 4 6 8 10 12 14
-1.5
-1
-0.5
0
0.5
1
1.5
d=7.025
d=4.88
d=-0.24
42 42
Effect of Data Transmission rate of application
0
0. 2
0. 4
0. 6
0. 8
1
1. 2
1. 4
1. 6
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183 190 197
0
0. 2
0. 4
0. 6
0. 8
1
1. 2
1. 4
1. 6
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183 190 197
0
0. 2
0. 4
0. 6
0. 8
1
1. 2
1. 4
1. 6
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183 190 197
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1 9 17 25 33 41 49 57 65 73 81 89 97 105 113 121 129 137 145 153 161 169 177 185 193
Every PMU measurement
Every second PMU measurement
Every tenth PMU measurement
Every second
43 43
Operator View of PMU data
46 46
Thank You