基于VSC-HVDC的风电场故障穿越控制

Fault ride-through method for wind farms through VSC-based HVDC transmission

针对我国面临的风电长距离输送问题以及直流输电系统多端化发展格局,提出基于三端直流输电系统的风电并网传输方案,并对其正常运行、风速波动和电压源换流站故障穿越等运行模式及其控制策略进行研究.通过功率外环控制实现风电场和备用电厂换流站间的自动切换,将多余功率转移至第三端输电线路,从而减小风电场换流站输出功率的过量积累,同时避免逆变换流站发生短路故障引起的直流母线泵升电压,配合电流内环的限幅给定控制,有效抑制换流站输出过电流.利用PSCAD/EMTDC仿真平台搭建基于甘肃酒泉某风电场的三端VSCHVDC输电系统,验证控制策略的正确性与可行性.

With the development of multi-terminal high-voltage direct-current transmission（HVDC） technology, a three-terminal voltage sourced converter （VSC-HVDC） network was presented in this paper for the large wind power transmission over long distance. The control strategies and operation mechanisms were discussed for normal as well as abnormal conditions when wind speed variation and VSC faults were considered. The VSC was injected to and extracted from the network by outer power control. Especially under AC short-circuit faults, the pumping-up voltage of DC-bus can be avoided, since the redundant energy transmitted by the third terminal In corporate with inner current loop, the output over-current of AC side converter is suppressed by limited given value. The feasibility and correctness were verified by PSCAD/EMTDC simulation which provides an alternative transmission scheme to the grid integration of wind power.