Grid code compliance assessment methods for grid connection of wind and PV power plants

IEC TS 63102:2021(E) highlights recommended technical methods of grid code compliance assessment for grid connection of wind and PV power plants as the basic components of grid connection evaluation. The electrical behaviour of wind and PV power plants in this technical specification includes frequency and voltage range, reactive power capability, control performance including active power based control and reactive power based control, fault ride through capability and power quality.
Compliance assessment is the process of determining whether the electrical behaviour of wind and PV power plants meets specific technical requirements in grid codes or technical regulations. The assessment methods include compliance testing, compliance simulation and compliance monitoring. The input for compliance assessment includes relevant supporting documents, testing results and validated simulation models, and continuous monitoring data. The scope of this technical specification only covers assessment methods from a technical aspect; processes related to certification are not included.
This technical specification is applicable to wind and PV power plants connected to the electrical power grid.

General Information

Status
Published
Publication Date
02-Sep-2021
Current Stage
PPUB - Publication issued
Completion Date
03-Sep-2021
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IEC TS 63102
Edition 1.0 2021-09
TECHNICAL
SPECIFICATION
colour
inside
Grid code compliance assessment methods for grid connection of wind and PV
power plants
IEC TS 63102:2021-09(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 63102
Edition 1.0 2021-09
TECHNICAL
SPECIFICATION
colour
inside
Grid code compliance assessment methods for grid connection of wind and PV
power plants
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160; 27.180 ISBN 978-2-8322-1022-1

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 63102:2021  IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 5

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms, definitions, abbreviations and subscripts .............................................................. 7

3.1 Terms and definitions .............................................................................................. 7

3.2 Abbreviations and subscripts .................................................................................. 8

3.2.1 Abbreviations ................................................................................................... 8

3.2.2 Subscripts ....................................................................................................... 9

4 Symbols and units ........................................................................................................... 9

5 General specifications ................................................................................................... 10

5.1 General ................................................................................................................. 10

5.2 Type tested units – Wind turbines and PV inverters .............................................. 10

5.3 Projects – Wind and PV power plants ................................................................... 10

5.4 Compliance assessment methods ......................................................................... 10

6 Operating area .............................................................................................................. 11

6.1 General ................................................................................................................. 11

6.2 Frequency range ................................................................................................... 11

6.2.1 Documentation .............................................................................................. 11

6.2.2 Method 1: Monitoring ..................................................................................... 11

6.3 Voltage range ....................................................................................................... 12

6.3.1 Documentation .............................................................................................. 12

6.3.2 Method 1: Simulation ..................................................................................... 12

6.3.3 Method 2: Monitoring ..................................................................................... 12

6.4 Reactive power capability ..................................................................................... 12

6.4.1 Documentation .............................................................................................. 12

6.4.2 Method 1: Simulation ..................................................................................... 12

6.4.3 Method 2: Monitoring ..................................................................................... 13

7 Control performance ...................................................................................................... 13

7.1 General ................................................................................................................. 13

7.2 Active power based control ................................................................................... 13

7.2.1 Documentation .............................................................................................. 13

7.2.2 Method 1: Plant field testing .......................................................................... 14

7.2.3 Method 2: Monitoring ..................................................................................... 17

7.2.4 Method 3: CHIL testing .................................................................................. 17

7.3 Reactive power based control ............................................................................... 19

7.3.1 Documentation .............................................................................................. 19

7.3.2 Method 1: Plant field testing .......................................................................... 20

7.3.3 Method 2: Monitoring ..................................................................................... 23

7.3.4 Method 3: CHIL testing .................................................................................. 23

8 Fault ride through .......................................................................................................... 24

8.1 General ................................................................................................................. 24

8.2 Documentation ...................................................................................................... 24

8.3 Method 1: Simulation ............................................................................................ 25

8.4 Method 2: Monitoring ............................................................................................ 27

9 Power quality ................................................................................................................. 28

9.1 General ................................................................................................................. 28

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IEC TS 63102:2021  IEC 2021 – 3 –

9.2 Current harmonics and inter-harmonics ................................................................. 28

9.2.1 Documentation .............................................................................................. 28

9.2.2 Method 1: Plant Field testing ......................................................................... 28

9.3 Flicker ................................................................................................................... 29

9.3.1 Documentation .............................................................................................. 29

9.3.2 Method 1: Plant field testing .......................................................................... 29

Annex A (informative) Monitoring of electrical performance of wind and PV power

plants.................................................................................................................................... 30

A.1 Overview............................................................................................................... 30

A.2 Responsibilities ..................................................................................................... 30

A.3 Basic principles ..................................................................................................... 30

A.4 Monitoring signals ................................................................................................. 30

A.5 Monitoring hardware ............................................................................................. 31

Annex B (informative) Controller hardware in the loop (CHIL) testing setup ......................... 32

B.1 General ................................................................................................................. 32

B.2 Power plant modelling ........................................................................................... 32

B.3 Set-up ................................................................................................................... 32

Annex C (informative) Harmonic simulation for wind and PV power plants ........................... 34

C.1 General ................................................................................................................. 34

C.2 General simulation methods .................................................................................. 35

Annex D (informative) Control performance index ................................................................ 37

Bibliography .......................................................................................................................... 38

Figure 1 – An example of PQ diagram ................................................................................... 13

Figure 2 – Example of figure for active power ramp rate test ................................................. 15

Figure 3 – Example of figure for set point test of active power .............................................. 15

Figure 4 – Example of figure for frequency control test ......................................................... 16

Figure 5 – Example of figure for frequency control test with simulated frequency

variation ................................................................................................................................ 18

Figure 6 – Example figure for set point control of reactive power as control reference

(reactive power control mode) ............................................................................................... 21

Figure 7 – Example of figure for set point control of voltage as control reference

(voltage control mode) .......................................................................................................... 22

Figure 8 – Example of figure for voltage control test ............................................................. 23

Figure 9 – Layout of grid with symmetrical fault .................................................................... 25

Figure 10 – Layout of grid with unsymmetrical fault ............................................................... 25

Figure 11 – Example of active power recovery ...................................................................... 27

Figure 12 – Equivalent circuit of the grid and the power plant ............................................... 29

Figure B.1 – Test bench diagram .......................................................................................... 33

Figure C.1 – Ideal harmonic current source illustration for harmonic distortion

calculation ............................................................................................................................ 34

Figure C.2 – Converter harmonic model as a Norton/Thevenin equivalent circuit .................. 35

Figure C.3 – Norton equivalent harmonic current source illustration for network

harmonic distortion calculation .............................................................................................. 35

Figure C.4 – Power electronics average model Norton equivalent circuit representation ....... 36

Figure D.1 – Performance index of active and reactive power based control ......................... 37

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– 4 – IEC TS 63102:2021  IEC 2021

Table 1 – Overview of assessment methods ......................................................................... 11

Table 2 – Example table for maximum variation value of active power .................................. 16

Table 3 – Example of table for performance index of set point test........................................ 17

Table 4 – Example of table for performance index of frequency control response ................. 17

Table 5 – Example of table for functionality test of frequency control .................................... 19

Table 6 – Example of table for coordination functionality of active power set point and

frequency control .................................................................................................................. 19

Table 7 – Example of table for reactive power control testing ................................................ 22

Table 8 – Example of table for voltage control testing ........................................................... 23

Table 9 – Example of table for voltage control test ................................................................ 24

Table 10 – Recommended scenario of pre-fault operation modes ......................................... 26

Table 11 – Recommended scenario of grid fault types and under/over voltage levels ............ 26

Table 12 – Example table for fault ride through simulation results ......................................... 27

Table A.1 – Monitoring signals .............................................................................................. 31

Table B.1 – CHIL system boundaries .................................................................................... 33

Table B.2 – Signal list ........................................................................................................... 33

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IEC TS 63102:2021  IEC 2021 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GRID CODE COMPLIANCE ASSESSMENT METHODS FOR GRID
CONNECTION OF WIND AND PV POWER PLANTS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

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with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

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transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

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Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC TS 63102 has been prepared by subcommittee SC 8A: Grid integration of renewable

energy generation, of IEC technical committee TC 8: System aspects of electrical energy

supply. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
8A/80/DTS 8A/86/RVDTS

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.

The language used for the development of this Technical Specification is English.

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– 6 – IEC TS 63102:2021  IEC 2021

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,

available at www.iec.ch/members_experts/refdocs. The main document types developed by

IEC are described in greater detail at www.iec.ch/standardsdev/publications.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it

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contents. Users should therefore print this document using a colour printer.
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IEC TS 63102:2021  IEC 2021 – 7 –
GRID CODE COMPLIANCE ASSESSMENT METHODS FOR GRID
CONNECTION OF WIND AND PV POWER PLANTS
1 Scope

This technical specification highlights recommended technical methods of grid code

compliance assessment for grid connection of wind and PV power plants as the basic

components of grid connection evaluation. The electrical behaviour of wind and PV power

plants in this technical specification includes frequency and voltage range, reactive power

capability, control performance including active power based control and reactive power

based control, fault ride through capability and power quality.

Compliance assessment is the process of determining whether the electrical behaviour of

wind and PV power plants meets specific technical requirements in grid codes or technical

regulations. The assessment methods include compliance testing, compliance simulation and

compliance monitoring. The input for compliance assessment includes relevant supporting

documents, testing results and validated simulation models, and continuous monitoring data.

The scope of this technical specification only covers assessment methods from a technical

aspect; processes related to certification are not included.

This technical specification is applicable to wind and PV power plants connected to the

electrical power grid.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60050-415:1999, International Electrotechnical Vocabulary – Part 415: Wind turbine

generator systems

IEC 61400-21-1, Wind energy generation systems – Part 21-1: Measurement and assessment

of electrical characteristics – Wind turbines

IEC 62934, Grid integration of renewable energy generation – Terms and definitions

3 Terms, definitions, abbreviations and subscripts
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 61400-21-1,

IEC 60050-415, IEC 62934 and the following apply.

ISO and IEC also maintain terminological database for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
---------------------- Page: 9 ----------------------
– 8 – IEC TS 63102:2021  IEC 2021
3.1.1
compliance monitoring

monitoring activity with the purpose of demonstrating the continuous compliance with the

required specifications throughout the lifetime of the power plant
3.1.2
compliance simulation

simulation activity with the purpose of demonstrating the compliance with the required

specifications, especially where testing is not applicable or risk of damaging the facility exists

3.1.3
controller hardware in the loop testing
CHIL testing

testing method for the subject controller based on physical and digital real-time simulation

Note 1 to entry: A simulation model is used to build the external real-time testing environment. Then a closed loop

test system is composed of the simulation model and embedded physical controller under test.

3.1.4
grid code

document that recommends practices or procedures for the activities of connection,

management, planning, development and maintenance of the electrical transmission and

distribution grid, as well as dispatching and metering, etc.
3.1.5
grid code compliance

demonstration that the electrical behaviours of power plants satisfy specific technical

requirements in grid codes or technical regulations
3.2 Abbreviations and subscripts
3.2.1 Abbreviations
The following abbreviations are used in this document:
CHIL controller hardware in the loop
CIGRE International Council on Large Electric Systems
CT Current Transformer
DB Dead Band
FACTS Flexible Alternating Current Transmission Systems
HVDC High Voltage Direct Current
OF Over Frequency
OVRT over-voltage ride-through
PCS power conditioning system
PV photovoltaic
POC point of connection
PQ active power and reactive power
SCR short circuit ratio
STATCOM static synchronous compensator
TS technical specification
UF Under Frequency
UVRT under-voltage ride-through
VT Voltage Transformer
---------------------- Page: 10 ----------------------
IEC TS 63102:2021  IEC 2021 – 9 –
3.2.2 Subscripts
F fault
meas measured value
max maximum
min minimum
n nominal
Omax maximum value of over voltage fault
poc-s produced by the grid
poc-c produced by the power plant
ref reference value
s variable of grid
sa phase A of grid
sb phase B of grid
sc phase C of grid
Umin minimum value of under voltage fault
4 Symbols and units
In this document, the following symbols and units are used.
I tested results of the current at POC (A)
poc
I harmonic currents produced by the grid (A)
poc-s
I harmonic currents produced by the power plant (A)
poc-c
I equivalent current of the grid
I equivalent current of the plant
P active power of the power plant (W)
P active power rated value (W)
P active power measured value (pu)
meas
P maximum long-term flicker
P maximum background long-term flicker
lt0
P maximum long-term flicker caused by power plant
ltRE
Q reactive power of the power plant (Var)
Q reactive power reference value (pu)
ref
Q reactive power measured value (pu)
meas
Q maximum reactive power at POC (Var)
max
Q minimum reactive power at POC (Var)
min
S short circuit power (VA)
U rated value of voltage at POC (V)
U voltage of the grid (V)
U phase A voltage of the grid (V)
U phase B voltage of the grid (V)
U phase C voltage of the grid (V)
U maximum voltage under normal operation at POC (V)
max
U minimum voltage under normal operation at POC (V)
min
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– 10 – IEC TS 63102:2021  IEC 2021
U minimum value under voltage according to gird codes (V)
Umin
U maximum value over voltage according to gird codes (V)
Omax
U tested results of the voltage at POC (V)
poc
Z equivalent impedance of the power plant (Ω)
Z equivalent fault impedance (Ω)
Z equivalent impedance of the grid (Ω)
Z phase A equivalent impedance of the grid (Ω)
Z phase B equivalent impedance of the grid (Ω)
Z phase C equivalent impedance of the grid (Ω)
5 General specifications
5.1 General

Technical requirements of wind and PV power plants for connecting to the grid were given in

the grid codes, such as operating area, active power control, reactive power control, fault ride

through, etc. Some existing IEC standards like IEC 61400-21 (all parts) and IEC 61400-27 (all

parts) specify the measurement procedures, modelling and validation methods of electrical

characteristics for wind turbines and wind power plants. This technical specification will

specify the compliance assessment methods of the electrical behaviours stipulated in the grid

codes.
5.2 Type tested units – Wind turbines and PV inverters

Type tested units are a series of wind turbines or PV inverters that have a common design,

materials and major components, subject to a common manufacturing process and uniquely

described by specific values or ranges of values of machine parameters and design

conditions. The definition of a type tested unit is dependent on the characteristics being

assessed and should be agreed by all stakeholders. Type testing is usually performed only

once per type in order to prove the general capability for all units of this type.

5.3 Projects – Wind and PV power plants

Wind or PV power plants are usually built clustering many units and jointly connecting them to

the grid. For these, a project based assessment needs to be performed. This means using

results from the type tested assessment, but taking the site-specific parameters into account.

5.4 Compliance assessment methods

In general, methods of project based compliance assessment can be classified into three

general categories:

• testing, including field testing and controller hardware in the loop (CHIL) testing;

• simulation;
• monitoring.
NOTE Annex A includes detailed information and recommendations for monitoring.

Normally for each electrical behaviour there is more than one compliance assessment method.

The selection of assessment methods should be carried out by system operators taking into

consideration the following factors:
• the technology of the project, including whet
...

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