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8/13/2019 5_ Ken Martin_Standards for Synchrophasor Measurement(1)
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STANDARDSFORSYNCHROPHASOR
MEASUREMENT
Ken Martin
EPG
WSU Workshop on PMU testing
March 16, 2012
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1
GPS
Real Time Monitoring & Alarming
Off-line Dynamics Analysis
Data
Storage
Phasor Measurement System
Future real-time controls:
Phasor Data Concentrator
Other utility PDC
Substation PDC
Measurement
standards
Communication
standards
Data
storage
standards
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Synchrophasor Standard History
IEEE 1344-1995
IEEE C37.1182005
Measurement requirements
Specified in terms of the result Error limits specified
Data transmission Messaging requirements only
Adapted to TCP/IP & UDP/IP
Measurements - IEEE C37.118.1-2011
Communications - IEEE C37.118.2-2011& IEC 61850-90-5
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New standard overview
Existing C37.118-2005 split into two standards
PC37.118.1
Covers measurements only Adds frequency & ROCOF, and dynamic operation
PC37.118.2 Preserves existing data exchange Adds needed current improvements (flags & configuration)
IEC 61850-90-5
Joint IEEE-IEC project for synchrophasor data communication Uses standard 61850 models & processes Adds communication methods where needed
Presentation covers measurements only
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Synchrophasor measurements
C37.118-2005 Basic compliance test is TVE
Phasor measurement accuracy over range of V, I, , & F
Rejection of harmonics and out of band signals (anti-aliasing)
Steady-state conditions only
No frequency & ROCOF requirements
22
r
2
i0i
2
0r
X
X-)(tXX
i
r
X
XtTVE
irjm
jXXeX
2
X
)()()( 000 tjXtXt ir X
Theoretical phasor value
Measured (estimated) phasor value
Total Vector Error (the RMS difference)
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Compliance Testing
Based on the measurement, not the method
Requires precise waveform generation/measurement
Phasor
Measurement
Unit (PMU)
UTC Time
(GPS)
X(n)= Xr(n)+jXi(n)X= Xr+jXi
X
Xi
Xr
X(n)
Xi(n)
Xr(n)
Phasor defined
at t = 0.
Waveform matches
phasor definitionat t = 0.
PMU estimates phasor
equivalent from an intervalof the waveform.
The estimate is comparedwith the defined phasor to
determine error (TVE).
TVE = [((Xr(n)- Xr)2
+ (Xi(n) - Xi)2
) / (Xr2
+ Xi2
)]
-1
-0.5
0
0.5
1
-0.012 -0.008 -0.004 0 0.004 0.008 0.012
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Synchrophasor Measurement Standard IEEE
C37.118.1
New C37.118.1 standard covers measurement aspects
Phasor, frequency, & ROCOF
(ROCOF is the acronym for Rate of Change of Frequency)
Retains existing steady-state requirements Adds clarification
Adds measurement requirements under dynamic conditions
Measurement bandwidth, tracking, and response time Test requirements keyed to apply to all measurements
Same tests for phasors, frequency, & ROCOF
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7
Synchrophasor definition generalizedF & ROCOF
defined
For a generalized case where amplitude, frequency, andphase are functions of time:
x(t) =Xm(t) cos(2f0t + (2 gdt +(t)))
The phasor value is:
X(t) = (Xm(t)/2)ej(2gdt+(t))
Similarly for the formula: x(t) = Xm cos [(t)]
Frequency is defined: f(t) = 1/(2) d(t)/dt
ROCOF is defined: ROCOF(t) = df(t)/dt
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Steady-state measurement changes
Influence quantity Reference
condition
Minimum range of influence quantity over which PMU shall be within
given TVE limit
Performance Class P Performance Class M
Range Max TVE (%) Range Max TVE
(%)
Signal frequency
rangefdev
(test applied
nominal +
deviation: f0 fdev)
Fnominal(f0) 2.0 Hz 1 2.0 Hz for Fs
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Steady-state OOB (filtering) changes
Minimal harmonic
Rejection, no OOB
for P class
For OOB rejection
signal is varied
from nominal
Influence quantity Reference
condition
Minimum range of influence quantity over which PMU shall be within given
TVE limitPerformance Class P Performance Class M
Range Max TVE (%) Range Max TVE
(%)
Harmonic distortion
(single harmonic)
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Steady-state Frequency & ROCOF
All new requirements
Influence quantity Reference conditionError Requirements for compliance
Class P Class MSignal Frequency Frequency = f0(fnominal)
Phase angle constant
Range: f0 2.0 Hz Range:
f0 2.0 Hz for Fs 10
Fs/5 for 10 Fs < 25
5.0 Hz for Fs25
Max FE Max RFE Max FE Max RFE
0.005 Hz 0.01 Hz/s 0.005 Hz 0.01 Hz/s
Harmonic distortion
(same as table 3)
(single harmonic)
20 0.005 Hz 0.01 Hz/s 0.025 Hz 6 Hz/s
Fs 20 0.005 Hz 0.01 Hz/s 0.005 Hz 2 Hz/s
Out-of-band interference
(same as table 3)
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Modulation Tests
Sinusoidal modulation of amplitude and phase angle of thefundamental signal
Determines the bandwidth of the measurement
Emulates a system oscillation
Amplitude-phase and phase only modulation
Xa= Xm[1+kxcos(t)] x cos [0t+kacos(t-)]
Phasor, F, & ROCOF responses (discrete points at time t - nT):
X(nT) = {Xm/2}[1+kxcos(nT)]{kacos(nT-)}
f(nT) = 0/2- ka(/2) sin (nT-)
ROCOF(nT) = - ka(2/2) cos (nT-)
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Modulation test requirements
Phasor measurementsModulation
Level
Reference condition Minimum range of influence quantity over which PMU shall be within
given TVE limit
Class P Class M
Range Max TVE Range Max TVE
kx= 0.1,
ka= 0.1 radian
100% rated signal
magnitude, fnominal
Modulation
frequency
0.1 to lesser
of Fs/10 or 2
Hz
3% Modulation frequency
0.1 to lesser of Fs/5 or
5 Hz
3%
kx= 0,ka= 0.1 radian
100% rated signalmagnitude, fnominal
3% 3%
Modulation level, Reference
condition, Range
Error Requirements for compliance
(Use the same modulation levels and
ranges under the reference conditions
specified in Table 5.
Class P Class M
Max FE Max RFE* Max FE Max RFE*
Fs> 20 0.06 Hz 3 Hz/s 0.3 Hz 30 Hz/s
Fs 20 0.01 Hz 0.2 Hz/s 0.06 Hz 2 Hz/s
Frequency & ROCOF measurements
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xample with amplitude modulation
Amplitude
modulation
pass & reject
bands for 30 fps
data rate.
Shown for 4
different filters
Modulation illustration:amplitude modulation
shows as envelope on
power frequency
waveform. It starts at a
low frequency and
increases until it is nolonger visible
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Frequency ramp and step tests
Constant ramp in frequency Determines measurement tracking system
Xa= Xmcos [w0t+Rft2] where Rf is a constant ramp rate
Emulates a system separation causing power-load imbalance
Step change of amplitude or phase
Determines response time measurement
Xa= Xm[1+kxf1(t)] x cos [0t+kaf1(t)] f1is a unit step
Emulates a switch action Measurement during step not testedonly response time
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Frequency ramp test requirements
Phasor measurements
Frequency & ROCOF measurements
Test
signalReference condition
Minimum range of influence quantity over which PMU
shall be within given TVE limit
Ramp rate (Rf) (positive
and negative ramp)
Performance
classRamp range Max TVE
Linear
frequency
ramp
100% rated signal
magnitude,
& fnominalat start or somepoint during the test
1.0 Hz/s P class 2 Hz 1%
M class Lesser of (Fs/5) or
5 Hza
1%
Signal
specification
Reference condition Transition timeError requirements for compliance
Ramp testssame as above
100% rated signalmagnitude and
0 radian base angle
2/Fsfor the startand end of ramp
P class M class
Max FE Max RFE Max FE Max RFE
0.01 Hz 0.1 Hz/s 0.005 Hz 0.1 Hz/s
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Ramp test example
Measurement algorithms must adapt or control error
Phasor error (on left) expands but stays within limits
Frequency estimate (on right) oscillates but within limit
0.5 1 1.5 2 2.5
0.5
1
1.5
2
2.5
3
3.5
4x 10
-3
Time (Sec)
TotalVectorError(PU)
Total Vector Error - A phase, pos ramp
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-12
-10
-8
-6
-4
-2
0
Time (Sec)
Frequencyestimate(Hz)
Algorithm Frequency Estimate (blue) & actual (green), negative ramp
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Step test requirements
Phasor measurements
Frequency & ROCOF measurements
Step change
specification
Reference
condition
Maximum response time, delay time, and overshoot
Class P Class MResponse
time (s)
|Delay time| Max
Overshoot
/undershoot
Response
time (s)
|Delay time| Max
Overshoot
/undershoot
Magnitude =
10%,
kx= 0.1,
ka= 0
nominal
at start or
end of
step
1.7/f0 1/(4xFs) 5% of step
magnitude
See table
11
1/(4 x Fs) 10% of step
magnitude
Angle 10,
kx= 0,ka= /18
nominal
at start orend of
step
1.7/f0 1/(4 xFs) 5% of step
magnitude
See table
11
1/(4 x Fs) 10% of step
magnitude
Signal
specification
Reference
condition
Maximum susceptibility response time
Class P Class MFrequency
Response time
ROCOF
Response time
Frequency
Response time
ROCOF
Response time
Magnitude test as
in Table 9
Same as in
Table 9
3.5/f0 4/f0 See Table 11 See Table 11
Phase test as in
Table 9
Same as in
Table 9
3.5/f0 4/f0 See Table 11 See Table 11
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Step Tests
Response time is how
quickly measurement
responds to step change
Delay time shows error
in phasor timingestimate
Susceptibility shows if
measurements that are
not changed have a
response (they should
show no change)
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Additional requirements
Reporting latency
Limits length of time before sending real-time data
Additional data rates
Reporting to 50 or 60 Hz
Slower rates synchronized with time for SCADA Test conditions more fully specified
Temperature, nominal signal level, signal noise, etc.
Classes changed into M & P
P class for minimal delay, no filtering (think Protection)
M class for more accurate reporting, may have delays (thinkMeasurement)
Either class can be used according to needs
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Ongoing issues
Need actual test data from PMUs New requirements are tested with models, not PMUs
Real PMUs may not meet models
Several ongoing issues
Possible minor errors in requirement numbers
Wording that may lead to different interpretation
Revision planned once feedback received
Adoption as a IEC standard 60255-118-1
Pending resolution of IEEE procedures & requirementresolution
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Standards summary
First synchrophasor standard in 1995 Measurement standard: IEEE C37.118.1-2011
Measurements only, complete performance set
Communication standards:
IEEE C37.118.2-2011
IEC 61850-90-5 (2011)
Data storage: profile for COMTRADE IEEE C37.111-1999 & IEC 60255-24 Ed2
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Synchrophasor Standards
Questions?