Measuring relays and protection equipment - Part 118-1: Synchrophasor for power systems - Measurements

IEC/IEEE 60255-118-1:2018 is used for synchronized phasor measurement systems in power systems. It defines a synchronized phasor (synchrophasor), frequency, and rate of change of frequency measurements. It describes time tag and synchronization requirements for measurement of all three of these quantities. It specifies methods for evaluating these measurements and requirements for compliance with the standard under both static and dynamic conditions. It defines a phasor measurement unit (PMU), which can be a stand-alone physical unit or a functional unit within another physical unit. This document does not specify hardware, software or a method for computing phasors, frequency, or rate of change of frequency.

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Status
Published
Publication Date
16-Dec-2018
Current Stage
PPUB - Publication issued
Completion Date
17-Dec-2018
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IEC/IEEE 60255-118-1
Edition 1.0 2018-12
INTERNATIONAL
STANDARD
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Measuring relays and protection equipment –
Part 118-1: Synchrophasor for power systems – Measurements
IEC/IEEE 60255-118-1:2018-12(en)
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IEC/IEEE 60255-118-1
Edition 1.0 2018-12
INTERNATIONAL
STANDARD
colour
inside
Measuring relays and protection equipment –
Part 118-1: Synchrophasor for power systems – Measurements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.70 ISBN 978-2-8322-6172-9

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
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– 2 – IEC/IEEE 60255-118-1:2018
© IEC/IEEE 2018
CONTENTS

FOREWORD ........................................................................................................................... 6

INTRODUCTION ..................................................................................................................... 8

1 Scope ............................................................................................................................ 10

2 Normative references .................................................................................................... 10

3 Terms, definitions, and abbreviated terms ..................................................................... 10

3.1 Terms and definitions ............................................................................................ 10

3.2 Abbreviated terms ................................................................................................. 11

4 Synchrophasor measurement ........................................................................................ 12

4.1 Input and output quantities .................................................................................... 12

4.2 Power system signal ............................................................................................. 12

4.3 Measurand definitions ........................................................................................... 13

4.3.1 Synchrophasor phase angle........................................................................... 13

4.3.2 Synchrophasor measurand ............................................................................ 13

4.4 Frequency measurand definition ........................................................................... 13

4.5 Rate of change of frequency measurand definition ................................................ 14

4.6 Measurement time synchronization ....................................................................... 14

5 Measurement compliance evaluation ............................................................................. 14

5.1 PMU measurement capability ................................................................................ 14

5.2 Measurement evaluation ....................................................................................... 14

5.2.1 Synchrophasor measurement evaluation ....................................................... 14

5.2.2 Frequency and ROCOF measurement evaluation .......................................... 15

5.2.3 Measurement response time and delay time .................................................. 15

5.2.4 Overshoot and undershoot ............................................................................. 16

5.2.5 Measurement reporting latency ...................................................................... 18

5.2.6 Measurement and operational errors ............................................................. 18

5.3 Measurement reporting ......................................................................................... 19

5.3.1 General ......................................................................................................... 19

5.3.2 Reporting rates .............................................................................................. 19

5.3.3 Reporting times ............................................................................................. 19

5.4 Measurement compliance ..................................................................................... 19

5.4.1 Performance classes ..................................................................................... 19

5.4.2 Compliance verification .................................................................................. 20

6 Measurement compliance test and evaluation ................................................................ 20

6.1 Testing considerations .......................................................................................... 20

6.2 Reference and test conditions ............................................................................... 21

6.3 Steady-state compliance ....................................................................................... 21

6.4 Dynamic compliance – Measurement bandwidth ................................................... 24

6.5 Dynamic compliance – Performance during ramp of system frequency .................. 27

6.6 Dynamic compliance – Performance under step changes in phase and

magnitude ............................................................................................................. 29

6.7 PMU reporting latency compliance ........................................................................ 30

7 Documentation .............................................................................................................. 31

Annex A (informative) Time tagging and dynamic response ................................................. 32

A.1 Dynamic response ................................................................................................ 32

A.2 Time tags .............................................................................................................. 32

A.3 Magnitude step test example ................................................................................ 34

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IEC/IEEE 60255-118-1:2018 – 3 –
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A.4 PMU time input ..................................................................................................... 35

Annex B (informative) Parameter representation and definition application examples .......... 37

B.1 General ................................................................................................................. 37

B.2 Representing non-stationary sinusoids .................................................................. 37

B.3 Introduction of definition application examples ...................................................... 38

B.3.1 General ......................................................................................................... 38

B.3.2 Example 1: steady-state at nominal frequency ............................................... 38

B.3.3 Example 2: steady-state and constant off-nominal frequency ......................... 38

B.3.4 Example 3: oscillation of the phase and amplitude of the power signal .......... 39

B.3.5 Example 4: constant, non-zero rate of change of frequency ........................... 40

B.4 Reconstruction of the power system sinusoidal signal from the

synchrophasor ...................................................................................................... 41

Annex C (informative) PMU evaluation and testing ............................................................... 42

C.1 General ................................................................................................................. 42

C.2 TVE measurement evaluation ............................................................................... 42

C.3 Phase-magnitude relation in TVE and timing ......................................................... 43

C.4 Evaluation of response to stepped input signals .................................................... 45

C.5 Harmonic distortion test signal phasing ................................................................. 47

C.6 ROCOF limits ........................................................................................................ 47

C.6.1 General ......................................................................................................... 47

C.6.2 Derivation ...................................................................................................... 48

C.7 PMU reporting latency........................................................................................... 49

Annex D (informative) Reference signal processing models ................................................. 50

D.1 General ................................................................................................................. 50

D.2 Basic synchrophasor estimation model ................................................................. 50

D.3 Timestamp compensation for low-pass filter group delay....................................... 51

D.4 Positive sequence, frequency, and ROCOF .......................................................... 52

D.5 P Class reference model for phasor ...................................................................... 53

D.6 P class filter details ............................................................................................... 53

D.7 M class reference model for phasor ...................................................................... 55

D.8 Data rate reduction model ..................................................................................... 57

D.9 Trade-offs in the reference model ......................................................................... 58

D.9.1 Immunity to off-nominal components, reporting latency and time

alignment ....................................................................................................... 58

D.9.2 Response time and the accuracy of synchrophasors, frequency and

ROCOF measurements .................................................................................. 59

Annex E (informative) Synchrophasor measurement using sampled value input to

PMU ..................................................................................................................................... 61

E.1 General ................................................................................................................. 61

E.2 Creation of sampled values ................................................................................... 61

E.3 Sources of synchrophasor error when using sampled values ................................. 62

E.4 Performance ......................................................................................................... 62

E.4.1 General ......................................................................................................... 62

E.4.2 Steady-state performance considerations ...................................................... 62

E.4.3 Dynamic performance considerations ............................................................ 63

E.4.4 Latency.......................................................................................................... 63

E.5 Proposed changes to performance requirements .................................................. 64

Annex F (informative) Suggested subset of tests for PMU evaluation under

environmental influences ...................................................................................................... 65

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© IEC/IEEE 2018

Annex G (normative) Extended accuracy specification for PMUs in steady-state .................. 66

G.1 General ................................................................................................................. 66

G.2 Applicable conditions ............................................................................................ 66

G.3 Accuracy specification .......................................................................................... 66

G.4 Usage examples ................................................................................................... 67

G.5 Preferred accuracy ranges .................................................................................... 67

G.6 Testing issues ....................................................................................................... 67

G.6.1 Testing for improved accuracy ....................................................................... 67

G.6.2 Testing at currents exceeding continuous thermal rating ................................ 68

G.6.3 Environmental considerations ........................................................................ 68

Annex H (informative) Generator voltage and power angle measurement ............................. 69

H.1 General ................................................................................................................. 69

H.2 Measurement methods .......................................................................................... 69

H.3 Input signal ........................................................................................................... 69

H.4 Measuring process ................................................................................................ 69

Annex I (normative) Extended PMU bandwidth classes ........................................................ 71

I.1 General ................................................................................................................. 71

I.2 Bandwidth determination ....................................................................................... 71

I.3 Enhanced bandwidth classes ................................................................................ 71

I.4 Testing issues ....................................................................................................... 72

Bibliography .......................................................................................................................... 73

Figure 1 – Input and output quantities ................................................................................... 12

Figure 2 – Step transition examples ...................................................................................... 17

Figure A.1 – Frequency step test phase response without group delay compensation ........... 33

Figure A.2 – Frequency step test phase response after group delay compensation ............... 33

Figure A.3 – Magnitude step test results for 3 different algorithms ........................................ 34

Figure A.4 – Magnitude step test example ............................................................................ 35

Figure B.1 – Sampling a power frequency sinusoid at off-nominal frequency ......................... 39

Figure C.1 – Total vector error (TVE) .................................................................................... 43

Figure C.2 – The 1 % TVE criterion shown on the end of a phasor ........................................ 43

Figure C.3 – TVE as a function of magnitude for various phase errors .................................. 44

Figure C.4 – TVE as a function of phase for various magnitude errors .................................. 45

Figure C.5 – Example of step change measurements using a magnitude step at t = 0 ........... 46

Figure C.6 – PMU reporting latency example (actual PMU measurement) ............................. 49

Figure D.1 – Single phase section of the PMU phasor signal processing model .................... 51

Figure D.2 – Complete PMU signal processing model ........................................................... 52

Figure D.3 – P class filter coefficient example (N = 2 × (16 – 1) = 30) ................................... 54

Figure D.4 – P class filter response as a function of frequency ............................................. 54

Figure D.5 – Reference algorithm filter frequency response mask specification for M

Class .................................................................................................................................... 56

Figure D.6 – M class filter coefficient example ...................................................................... 57

Figure D.7 – Data rate reduction signal processing model ..................................................... 58

Figure D.8 – Factors affecting estimation .............................................................................. 58

Figure D.9 – Reference filter magnitude frequency response with Fs = 60 fps ....................... 59

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IEC/IEEE 60255-118-1:2018 – 5 –
© IEC/IEEE 2018

Figure E.1 – Synchrophasors having sampled values as inputs............................................. 61

Figure H.1 – Phasor diagram under no-load conditions ......................................................... 70

Figure H.2 – Phasor diagram with load on generator ............................................................. 70

Table 1 – Standard PMU reporting rates ............................................................................... 19

Table 2 – Steady-state synchrophasor measurement requirements ....................................... 22

Table 3 – Steady-state frequency and ROCOF measurement requirements .......................... 24

Table 4 – Synchrophasor measurement bandwidth requirements using modulated test

signals .................................................................................................................................. 26

Table 5 – Frequency and ROCOF performance requirements under modulation tests ........... 26

Table 6 – Synchrophasor performance requirements under frequency ramp tests ................. 29

Table 7 – Frequency and ROCOF performance requirements under frequency ramp

tests ..................................................................................................................................... 29

Table 8 – Phasor performance requirements for input step change ....................................... 30

Table 9 – Frequency and ROCOF performance requirements for input step change .............. 30

Table 10 – PMU reporting latency ......................................................................................... 30

Table C.1 – Harmonic phase sequence in a balanced three-phase system............................ 47

Table D.1 – M class low pass filter parameters ..................................................................... 57

Table E.1 – Summary of proposed performance requirement changes .................................. 64

Table G.1 – Conditions for extended accuracy tests .............................................................. 66

Table I.1 – Conditions for extended bandwidth testing .......................................................... 71

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© IEC/IEEE 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASURING RELAYS AND PROTECTION EQUIPMENT –
Part 118-1: Synchrophasor for power systems – Measurements
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IEC/IEEE 60255-118-1:2018 – 7 –
© IEC/IEEE 2018

International Standard IEC/IEEE 60255-118-1 has been prepared by IEC technical committee

95: Measuring relays and protection equipment, in cooperation with the Power System Relaying

Committee of the IEEE Power and Energy Society , under the IEC/IEEE Dual Logo Agreement.

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