Electric Power ›› 2022, Vol. 55 ›› Issue (11): 66-72.DOI: 10.11930/j.issn.1004-9649.202105025

• Power System • Previous Articles     Next Articles

Virtual Synchronization Control Strategy for UHVDC with Secondary Frequency Modulation Based on PI Control

GUO Xiaolong1, ZHANG Jiangfei2, KANG Pengpeng1, YANG Guixing1, SUN Yiqian1, YUAN Tiejiang2, LIU Yong3   

  1. 1. State Grid Xinjiang Electric Power Co., Ltd., Urumqi 830002, China;
    2. School of Electrical Engineering, Dalian University of Technology, Dalian 116024, China;
    3. Anhui Zhengguangdian Electric Power Technology Co., Ltd., Hefei 230088, China
  • Received:2021-05-08 Revised:2021-06-05 Published:2022-11-29
  • Supported by:
    This work is supported by National Natural Science Foundation of China (No.51577163).

Abstract: Under traditional control strategy, UHVDC transmission system lacks inertia and damping characteristics, so it can't effectively adjust the frequency of AC system dynamically. In order to solve this problem, a VSG (virtual synchronous generator)-based control strategy for UHVDC converter stations is proposed, in which two key parameters, including synchronous generator rotational inertia and damping coefficient, are retained. Meanwhile, the calculation method for frequency in virtual rotor is improved, and the PI controller-based secondary frequency regulation is added. Aiming at the situation of load mutation, a two-terminal VSG system model is built for simulation with Matlab/Simulink. The results show that the proposed control strategy has the characteristics of inertia and damping, which can reduce the amplitude, speed and overshoot of frequency fluctuation, suppress the voltage fluctuation of DC system, and realize isochronous control of frequency.

Key words: UHVDC, virtual synchronous generator, rotational inertia, damping coefficient, DC voltage control, secondary frequency modulation