关键词: 柔性直流输电(VSC-HVDC), 孤岛送出, 暂态过电压, 抑制策略

Abstract: voltage source converter based high voltage direct current (VSC-HVDC) has a broad application prospect in the field of islanded renewable energy transmission due to its advantages such as no commutation failure. When AC fault occurs in the AC power grid at the sending end of the islanded wind power transmission via VSC-HVDC, AC transient overvoltage occurs after the fault is cleared, which endangers the safety of the wind turbine and VSC equipment. Taking the doubly fed induction generator (DFIG) as an example, this paper focused on the VSC-HVDC based on modular multilevel converter (MMC), and carried out a research on the strategy of suppressing AC transient overvoltage for MMC. Firstly, this paper analyzed the mathematical model of MMC and DFIG, and pointed out that the transient overvoltage was caused by the reactive power provided by MMC and DFIG. On this basis, combined with MMC control system model, a transient overvoltage auxiliary suppression strategy was proposed to reduce the reactive power output according to the AC voltage recovery. Finally, the effectiveness of the proposed strategy was verified by simulation on PSCAD using Zhangbei MMC-HVDC project model.

Key words: voltage source converter based high voltage direct current (VSC-HVDC), islanded transmission, transient overvoltage, suppression strategy