IEC TR 63401-3:2023

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
...