Electric Power ›› 2021, Vol. 54 ›› Issue (12): 11-19,44.DOI: 10.11930/j.issn.1004-9649.202010078

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SVG Based Supplementary Damping Mitigation Strategy for Sub-Synchronous Oscillation in Grid-connected Photovoltaic Plants

ZHANG Fan1, GAO Benfeng2, LI Tiecheng3   

  1. 1. Baoding Power Supply Company of State Grid Hebei Electric Power Co., Ltd., Baoding 071000, China;
    2. Key Laboratory of Distributed Energy Storage and Microgrid of Hebei Province (North China Electric Power University), Baoding 071003, China;
    3. State Grid Hebei Electric Power Co., Ltd., Electric Power Research Institute, Shijiazhuang 050021, China
  • Received:2020-10-26 Revised:2021-09-08 Online:2021-12-05 Published:2021-12-16
  • Supported by:
    This work is supported by National Natural Science Foundation of China (No.51507064) and Fundamental Research Funds for the Central Universities of the Ministry of Education (No.2018MS087).

Abstract: To mitigate the sub synchronous oscillation (SSO) in large-scale photovoltaic (PV) plants integrated to weak AC networks, a static var generator (SVG) based supplementary damping control strategy is proposed. The strategy extracts the voltage at the PV coupling point as input signal, and produces the sub-synchronous current that is in the same phase with the sub-synchronous voltage at the coupling point through supplementary sub-synchronous damping controller (SSDC). Thus, the SVG is equivalent to the positive resistance of the accessing the system in parallel at the sub-synchronous frequency, and dissipates the SSO energy for suppression. In addition, the structure and parameter design method of SSDC are analyzed in detail. Finally, taking a PV plant in northwest China as an example, the mitigation effectiveness of the proposed control strategy is verified under various working conditions through electromagnetic transient simulation, which shows that the proposed control strategy can improve the stability margin of the photovoltaic system.

Key words: static var generator, photovoltaic plant, weak AC networks, sub-synchronous oscillation, supplementary damping control