抑制高压直流系统后续换相失败的定关断角控制改进方法

定关断角控制是高压直流输电系统抑制换相失败的主要控制策略之一，但当前针对其实测型和预测型控制的研究仍未能有效解决其响应速度与控制精度不足的问题，因此提出了抑制后续换相失败的关断角控制改进方法。首先，基于对直流系统换相过程及影响因素的分析，提出了考虑电压谐波的关断角预测方法。然后，将后续换相过程的关断角预测值引入直流系统的原有控制逻辑，从而改进定关断角控制策略。最后，基于PSCAD/EMTDC对改进后的控制方法进行了仿真分析和验证。仿真结果验证了该方法能有效地抑制直流系统的后续换相失败，提升了定关断角控制的响应速度和控制精度。

Enhanced extinction angle control for subsequent commutation failure mitigation in HVDC systems

Extinction angle control is one of the main control strategies for commutation failure mitigation in an HVDC, but the problem of too slow response and control precision still cannot be solved effectively based on the current research on measured and predictive extinction angle control. Thus, an improved extinction angle control method to mitigate subsequent commutation failure is proposed. First, the influence of voltage harmonics on the commutation process of the HVDC system is analyzed, and the prediction method of extinction angle considering voltage harmonics is proposed. Then the predictive value of the subsequent commutation process is introduced into the original control logic of the system to improve extinction angle control. Finally, the proposed control method is simulated and verified based on PSCAD/EMTDC standard test system. The simulation results show that the method can improve the response speed and control precision of the extinction angle control, and thus can effectively mitigate the subsequent commutation failure in HVDC system.