5_ Ken Martin_Standards for Synchrophasor Measurement(1)

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


2/23

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


3/23

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


4/23

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


5/23

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)


6/23

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


7/23

6

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


8/23

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


9/23

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


10/23

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)


11/23

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)


12/2311

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-)


13/23

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


14/23

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


15/2314

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


16/23

Frequency ramp test requirements

Phasor 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


17/2316

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


18/23

Step test requirements

Phasor 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


19/2318

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)


20/2319

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


21/23

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


22/23

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

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5_ Ken Martin_Standards for Synchrophasor Measurement(1)