提出了一种基于多角度预测的混合双馈入直流输电系统换相失败抑制策略. 结合定关断面积预测法和零序检测及αβ 转换预测法的优势综合得出关断角参考值γref, 利用关断角参考值γref和关断角设定值γset的差值获得无功补偿量, 附加至电压源型换流器高压直流输电(VSC-HVDC)的外环无功控制环节, 调节其故障后发出的无功功率, 提升电网换相换流器高压直流输电(LCC-HVDC)抵御换相失败的能力. 该方法不依赖于对LCC-HVDC关断角的实时测量, 在实际工程中更易实现. 采用PSCAD/EMTDC 进行了算例仿真分析, 仿真结果证明了该控制策略的有效性.

In order to take full advantage of the ability of voltage source converter high voltage direct current (VSC-HVDC) to support the reactive power of the ac system, and suppress commutation failures of line-commutated converter high voltage direct current (LCC-HVDC), this paper proposes a commutation failure suppression strategy based on multi-angle prediction in hybrid dual-infeed HVDC system. Combining two prediction methods, constant extinction area prediction and zero-sequence detection and αβ transform prediction, we obtain the extinction angle reference γref. Then, the required reactive power that is calculated by the difference between the extinction angle reference γref and the setting value γset is fed back to the VSC control loop to adjust the reactive power that VSC generates after fault occurs,and thus to improve the immune ability to commutation failure of LCC. This method doesn’t depend on the mesurement of real extinction angle, so it’s more easier to implement. The simulation result obtained in PSCAD/EMTDC shows that the proposed strategy can improve the ability of suppressing commutation failures of LCC-HVDC.