IEC TR 63401-3:2023

Dynamic characteristics of inverter-based resources in bulk power systems - Part 3: Fast frequency response and frequency ride-through from inverter-based resources during severe frequency disturbances

IEC TR 63401-3:2023, which is a Technical Report, provides an insight into the various forms of fast frequency response and frequency ride-through techniques that involve inverter-based generation sources (mainly wind and PV) in a bulk electrical system.
This document first focuses on extracting the clear definition of FFR from different references around the world, while studying the mechanism of FFR acting on system frequency and the unique features of FFR. It then compares various kinds of frequency response and demonstrates the relationship among synchronous inertia response, fast frequency response, and primary frequency response. Several system needs and conditions where FFR is suitable are identified. This document also focuses on the performance objectives, practicality and capabilities of various non-synchronous resources, and discusses the test methods for verifying FFR capability at different levels. Finally, it focuses on the ROCOF issues and on the robust performances of FFR. .

General Information

• Status: Published
• Publication Date: 13-Dec-2023
• ICS: 27.160 - Solar energy engineering
• ICS: 27.180 - Wind turbine energy systems
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: SC 8A - Grid Integration of Renewable Energy Generation
• Drafting Committee: JWG 5 - TC 8/SC 8A/JWG 5
• Current Stage: PPUB - Publication issued
• Start Date: 12-Jan-2024
• Completion Date: 14-Dec-2023

Standards Content (Sample)

IEC TR 63401-3 ®
Edition 1.0 2023-12
TECHNICAL
REPORT
colour
inside
Dynamic characteristics of inverter-based resources in bulk power systems –
Part 3: Fast frequency response and frequency ride-through from inverter-based
resources during severe frequency disturbances

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IEC TR 63401-3 ®
Edition 1.0 2023-12
TECHNICAL
REPORT
colour
inside
Dynamic characteristics of inverter-based resources in bulk power systems –

Part 3: Fast frequency response and frequency ride-through from inverter-

based resources during severe frequency disturbances

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160; 27.180; 29.020 ISBN 978-2-8322-8000-3

– 2 – IEC TR 63401-3:2023  IEC 2023
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Definition of fast frequency response (FFR) . 11
4.1 General . 11
4.2 Existing usage of term FFR . 11
4.2.1 FFR in Australia and Texas . 11
4.2.2 FFR and synthetic inertia in European Network of Transmission System
Operators for Electricity (ENTSO-E) . 15
4.2.3 FFR and synthetic inertia in EirGrid/SONI . 16
4.2.4 The enhanced frequency response and enhanced frequency control
capability in the UK . 18
4.2.5 FFR in North American Electric Reliability Council (NERC) and North
America . 18
4.3 Definition of FFR given by CIGRE JWG C2/C4.41 . 18
4.4 Recommended definition of fast frequency response (FFR) . 19
4.4.1 Clear definition . 19
4.4.2 Impact mechanism on system frequency . 19
4.5 Description of the relationship among synchronous inertia response, fast
frequency response, and primary frequency response . 20
4.5.1 Relationship between synchronous inertia response and fast frequency
response . 20
4.5.2 Relationship between fast frequency response and primary frequency
response . 21
4.5.3 Relationship between synchronous inertia response and primary
frequency response . 21
5 System needs and conditions where fast frequency response is warranted . 22
5.1 Higher ROCOF and lower nadir . 22
5.1.1 General . 22
5.1.2 Higher ROCOF . 23
5.1.3 Worse nadir . 24
5.1.4 Simulation study . 25
5.1.5 Blackout in Great Britain power grid on 9 August 2019 . 26
5.2 Large fluctuation of system frequency in power system operation . 29
5.2.1 General . 29
5.2.2 Frequency regulation scheme . 29
5.2.3 Relatively large load fluctuation . 30
5.2.4 Relatively weak and slow PFR . 30
6 Performance objectives for fast frequency response from inverter-based resources . 31
6.1 The response time of FFR . 31
6.2 The response characteristics and maximum response capacity of FFR . 32
6.3 Test performance for renewable generator equipped with fast frequency
response in China . 34
6.3.1 General . 34

6.3.2 Engineering construction . 34
6.3.3 Test practice and performance . 35
7 Available technologies, controls, and tuning considerations for fast frequency
response and primary frequency response. 35
7.1 Available technologies for fast frequency response . 35
7.1.1 Technology capabilities for FFR service. 35
7.1.2 Wind turbines . 36
7.1.3 Solar PV . 37
7.1.4 Battery energy storage . 38
7.1.5 HVDC . 40
7.2 Available controls for fast frequency response . 41
7.2.1 General . 41
7.2.2 Additional FFR control for grid-following converter . 41
7.2.3 Grid-forming converter control . 42
7.3 Tuning considerations for fast frequency response and primary frequency

response . 44
8 Test methods for verifying turbine-level or plant-level fast frequency response
capability . 45
8.1 General . 45
8.2 Selection of test equipment . 45
8.3 Test wiring method. 45
8.4 Selection of measuring conditions . 46
8.5 Step frequency disturbance test . 47
8.6 Slope frequency disturbance test . 47
8.7 Actual frequency disturbance simulation test . 48
8.8 Actual frequency disturbance simulation test . 48
9 Rate-of-change-of-frequency (ROCOF) definition and withstand capability for high
ROCOF conditions . 49
9.1 Definition of rate of change of frequency (ROCOF) . 49
9.2 Ride-through (withstand) capability for high ROCOF conditions . 51
10 Test specifications for high ROCOF conditions . 53
10.1 Performance specification . 53
10.1.1 Effective and operating ranges . 53
10.1.2 Accuracy related to the characteristic quantity . 53
10.1.3 Start time for rate of change of frequency (ROCOF) function . 54
10.1.4 Accuracy related to the operate time delay setting . 54
10.1.5 Voltage input . 54
10.2 Functional test methodology . 55
10.2.1 General . 55
10.2.2 Determination of steady-state errors related to the characteristic
quantity . 55
10.2.3 Determination of the start time . 63
10.2.4 Determination of the accuracy of the operate time delay . 65
10.2.5 Determination of disengaging time . 66
11 Modelling capabilities and improvements to dynamic models for fast frequency

response and related high ROCOF conditions . 67
11.1 General . 67
11.2 Dynamic models for fast frequency response and related high ROCOF
conditions . 68
11.2.1 Dynamic models of whole power systems . 68

– 4 – IEC TR 63401-3:2023  IEC 2023
11.2.2 Simplification of dynamic models . 73
11.3 Modelling improvements . 75
Bibliography . 77

Figure 1 – Proposed response times by ERCOT as of 2014 . 12
Figure 2
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