Electric Power ›› 2022, Vol. 55 ›› Issue (3): 18-27.DOI: 10.11930/j.issn.1004-9649.202101098

• Power System • Previous Articles     Next Articles

Adaptive Back-stepping Stability Control Strategy for MMC Based on Legendre Polynomial

XU Lei1, XIA Xiangyang1, JING Huabing2, LIU Yixuan1, HE Yedan1, YI Haigan1   

  1. 1. College of Electrical and Information Engineering, Changsha University of Science & Technology, Changsha 410114, China;
    2. Zhuzhou CRRC Electromechanical Technology Co., Ltd., Zhuzhou 412005, China
  • Received:2021-01-19 Revised:2021-07-24 Online:2022-03-28 Published:2022-03-29
  • Supported by:
    This work is supported by National Natural Science Foundation of China (Research on Energy Regulation Mechanism and Fault Ride-through Control of Multi-armed Converter of AC Side Fault in MMC-HVDC System, No. 51977014)

Abstract: In view of the poor stability control performance and frequent operation faults of the flexible HVDC transmission system due to the parameter changes of system dynamic model structure caused by serious signal interference or device temperature rise during the operation of the modular multilevel converter(MMC), an adaptive back-stepping stability control strategy is proposed based on Legendre polynomial. Firstly a dynamic model is established in a static a-b-c coordinate system, and the Legendre polynomial, which has advantages of simple structure and no modeling, is used to approximately compensate for the error value caused by the parameter changes in MMC, thus eliminating its effects on dynamic model. Then, the back-stepping control theory is used to select the state variables, construct the Lyapunov function, and obtain the control variables that meet the requirements of Lyapunov stability. Finally, simulation verification is carried out through PSCAD/EMTDC, which shows that the control strategy proposed in this paper has better control ability and robustness than the conventional PI control strategy.

Key words: modular multilevel converter, dynamic model, back-stepping method, adaptive control, Legendre polynomial