Electric Power ›› 2022, Vol. 55 ›› Issue (7): 11-21.DOI: 10.11930/j.issn.1004-9649.202106054

• Power System • Previous Articles     Next Articles

Key Factors of Medium-High Frequency Oscillation in Chongqing-Hubei HVDC System and Suppression Strategies

LI Qinan1,2, XIA Yongjun3, ZHANG Xiaolin1,2, SUN Baokui1,2, SUN Huadong4, ZHANG Fan1,2, LI Lanfang1,5, YANG Yuefeng1,2, HAN Qingtao6   

  1. 1. NARI Group Corporation (State Grid Electric Power Research Institute), Nanjing 211006, China;
    2. Beijing DC Transmission and Distribution Engineering Technology Research Center(China-EPRI Electrical Engineering Co., Ltd.), Beijing 102200, China;
    3. Electric Power Research Institute of State Grid Hubei Electric Power Co., Ltd., Wuhan 430061, China;
    4. China Electric Power Research Institute, Beijing 100192, China;
    5. China EPRI Science & Technology Co., Ltd., Beijing 102200, China;
    6. State Grid Hubei DC Inspection Company, Yichang 443001, China
  • Received:2021-06-24 Revised:2022-05-10 Online:2022-07-28 Published:2022-07-20
  • Supported by:
    This work is supported by Science and Technology Project of SGCC (Research on Dynamic Power Coordinated Control of Near Area Power Grid with VSC/LCC Parallel Hybrid Multi-feed, No.5100-202022011 A-0-0-00)

Abstract: For the problem of medium and high frequency oscillations in flexible HVDC projects, the existing solution is to add a filter in the voltage feedforward path to suppress high frequency oscillations, which, however, increases the risk of medium frequency oscillations. For this reason, a method is proposed to avoid medium-high frequency oscillations by adjusting the control link delay based on the south channel of the Chongqing-Hubei flexible HVDC transmission project. Firstly, a impedance model of MMC converter station is established based on the principle of multi-harmonic linearization, and a comprehensive analysis is made on the influence of control link delay and grid voltage feedforward strategy on the impedance characteristics of MMC converter station and system stability. And then, the feasibility of adjusting the delay of the control link to avoid the medium-high frequency oscillation is discussed, and the method for selecting the time delay of the control link is given. Finally, based on PSCAD/EMTDC electromagnetic transient simulation, it is verified that the proposed method can achieve the suppression of the medium-high frequency oscillations in both the Hubei-side and Chongqing-side systems. Meanwhile, the proposed method has minor effect on the dynamic characteristics of the system.

Key words: modular multilevel converter (MMC), impedance characteristic, medium-high frequency oscillation, time delay, flexible HVDC transmission