IEC TR 63401-2:2022

IEC TR 63401-2 ®
Edition 1.0 2022-06
TECHNICAL
REPORT
colour
inside
Dynamic characteristics of inverter-based resources in bulk power systems –
Part 2: Sub- and super-synchronous control interactions
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IEC TR 63401-2 ®
Edition 1.0 2022-06
TECHNICAL
REPORT
colour
inside
Dynamic characteristics of inverter-based resources in bulk power systems –

Part 2: Sub- and super-synchronous control interactions

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160, 27.180, 29.020 ISBN 978-2-8322-3929-2

– 2 – IEC TR 63401-2:2022  IEC 2022
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 10
4 Terms, definitions and classification . 11
4.1 Existing terms, definitions and historical background . 11
4.1.1 General . 11
4.1.2 Subsynchronous resonance (SSR) . 12
4.1.3 Device dependent SSO (DDSSO) . 13
4.2 Necessity to revisit the terms and classification . 13
4.3 Revisiting the terms and classification . 13
4.3.1 General . 13
4.3.2 Torsional interaction . 14
4.3.3 Network resonance . 15
4.3.4 Control interaction . 15
4.4 Clause summary . 16
5 SSCI incidents in real-world wind power systems . 16
5.1 General . 16
5.2 SSCI in DFIGs connected to series-compensated networks . 17
5.2.1 ERCOT SSCI incident in 2009 . 17
5.2.2 ERCOT SSCI events in 2017 . 18
5.2.3 SSCI events in Guyuan wind power system . 20
5.3 SSCI in FSC-based generators connected to weak AC network . 24
5.3.1 SSCI event in Hami wind power system . 24
5.4 Clause summary . 27
6 Modeling and analysis approaches . 28
6.1 Preview . 28
6.2 Time-domain modeling and analysis approaches . 28
6.2.1 General . 28
6.2.2 Nonlinear time-domain EMT simulation . 28
6.2.3 Controller hardware-in-the-loop simulation . 28
6.2.4 Linearized state-space modeling and modal analysis . 29
6.2.5 Discussions on time-domain approaches for SSCI studies . 30
6.3 Frequency-domain modeling and analysis approaches . 30
6.3.1 Frequency scanning . 30
6.3.2 Complex torque coefficient method . 31
6.3.3 Impedance-based modeling and analysis . 33
6.4 Guidelines on the approaches to SSCI studies . 39
6.5 Clause summary . 40
7 Proposed benchmark models . 40
7.1 Overview. 40
7.2 Benchmark model based on Guyuan wind power system . 40
7.2.1 General . 40
7.2.2 Configuration and parameters of the WTGs and Guyuan substation . 41
7.2.3 Parameters of the DFIG's converter control . 41

7.2.4 Series-compensated electrical network . 41
7.2.5 Case study . 41
7.3 Benchmark model based on Hami wind power system . 42
7.3.1 General . 42
7.3.2 Configuration and parameters of FSCs . 43
7.3.3 Configuration and parameters of LCC-HVDC . 43
7.3.4 Synchronous generators . 45
7.3.5 Electrical network . 45
7.3.6 Case studies . 45
7.4 Clause summary . 46
8 Mitigation methods . 46
8.1 General . 46
8.2 Bypassing the series capacitor . 47
8.3 Selective tripping of WTGs . 47
8.4 Network/Grid-side subsynchronous damping controller (GSDC) . 48
8.5 Generation-side subsynchronous mitigation schemes . 50
8.5.1 Adjusting the wind turbine converter control parameters . 50
8.5.2 Adding an SSDC in the RSC control loop . 51
8.5.3 Adding an SSDC in the GSC control loop . 53
8.6 Protection schemes . 54
8.7 Clause summary . 54
9 Future work . 54
Annex A (Informative) . 56
Bibliography . 60

Figure 1 – Multi-frequency oscillations in the modern power system with high-share of
renewables and power electronic converters . 10
Figure 2 – Timeline of the historical developments of SSO terms, definitions and
classification [12] . 11
Figure 3 – Terms and classification of SSR by IEEE [13] . 12
Figure 4 – Classification of subsynchronous interaction based on the origin [12]. 14
Figure 5 – Reclassification of subsynchronous interactions based on the interaction
mechanism . 14
Figure 6 – Timeline of SSCI events reported around the world . 16
Figure 7 – Structure of the ERCOT wind power system in 2009 [16]. 17
Figure 8 – Oscilloscope record of the 2009 SSCI event in the ERCOT system [19] . 18
Figure 9 – Structure of the ERCOT wind power system in 2017 [24]. 18
Figure 10 – Event#1 August 24, 2017: current, voltage and frequency spectrum of the
current during the SSCI event and after bypassing the series capacitor [24] . 19
Figure 11 – Event#2 September 27, 2017: current, voltage and frequency spectrum of
the current during the SSCI event [24] . 20
Figure 12 – Event#3 October 27, 2017: current, voltage and frequency spectrum of the
current during the SSCI event [24] . 20
Figure 13 – Geographical layout of the Guyuan wind power system, Hebei Province,
China . 21
Figure 14 – Power flow measured at the 200 kV side of the Guyuan step-up
transformer . 22
Figure 15 – Field recorded line current and frequency spectrum . 22

– 4 – IEC TR 63401-2:2022  IEC 2022
Figure 16 – Field recorded voltage and frequency spectrum . 23
Figure 17 – Hami wind power system, Xinjiang, China [27] . 24
Figure 18 – Current (upper plot) and active power (lower plot) . 25
Figure 19 – Frequency spectrum of the current (upper plot) and active power (lower
plot) . 25
Figure 20 – Field measured active power of a wind farm (a) From 09:46 to 09:47 (b)
From 11:52 to 11:53. 26
Figure 21 – Torsional modes and frequency variati
...