柔性直流与交流并列输电换流器交流故障穿越

HVDC Flexible Converter AC Fault Ride-through with AC Parallel Transmission

柔性直流输电的故障穿越是电网安全稳定运行的重要内容,特别是交流侧低压故障时产生的较大短路电流对换流器件的危害一直是研究热点。针对1个风电场经交直流并联输电的系统,当直流输电的逆变端交流侧发生严重短路故障时,提出通过控制换流站的内环电流控制器的输入电流指令的限幅环节来抑制换流器出口的过电流,即低压故障时切换到小一级的限幅器限值,同时为了阻止从整流站而来的功率积累过剩,造成直流电压上升,设计了整流站运行方式自动切换控制器,使整流站输电功率减小,将功率转移到交流线路,以稳定直流电压。最后通过仿真验证,证明提出的方法在抑制交流短路大电流、稳定直流电压方面效果显著。

Fauh ride-through is an important issue of security arid stability of HVDC flexible, particularly the serious harm of converter device caused by AC short circuit current, which has been concerned along with HVDC＇s development. This article relates to a system with the windfarms through AC-DC parallel transmission, and proposes the method of fault ride-through. When the inverter oecurrs serious AC short-circuit fault, this method can reduce current limits of inner current controller of inverter dynamically which restrains the large short-circuit current, and switch active power nperation mode of rectifier automatically which restrains DC vohage ascent by reducing transmission of power. Finally, simulation waveforms prove that effects of the method proposed is remarkable in restraining fault current and DC voltage during AC short-circuit fault.