基于虚拟电阻的高压直流换相失败期间送端电网暂态过电压抑制方法

针对高压直流输电系统换相失败易引发送端电网暂态过电压的问题，提出了一种基于虚拟电阻控制的送端电网暂态过电压抑制方法。分析了高压直流系统发生换相失败期间整流站交流侧的无功动态特性及其引发送端电网暂态过压的机理。根据影响暂态过电压水平的关键直流控制变量分析并结合换相裕度边界条件，设计了基于虚拟电阻的送端暂态过压控制器。控制器可根据送端电网暂态过压水平动态调整整流站触发角，实现送端电网的暂态过电压抑制目标。仿真算例表明，所提控制方法通过虚拟电阻环节与常规定电流控制协调配合，能有效抑制换相失败期间送端电网暂态过电压水平。

A suppression method for overvoltage of a sending end grid caused by commutation failure based on virtual resistance

There is a transient overvoltage problem at the sending end grid during a commutation failure in an HVDC transmission system. We therefore propose a transient overvoltage suppression method of the sending end grid based on virtual resistance control of the rectifier station. The reactive power dynamic characteristics at the AC side of the rectifier station during the commutation failure and the mechanism that contributes to the transient overvoltage of the sending end grid is analyzed. By analyzing the key DC control variables that affect the transient overvoltage and combining the commutation margin boundary conditions, a sending end grid transient overvoltage suppression controller based on virtual resistance is designed. The controller can dynamically adjust the trigger delay angle of the rectifier station according to the transient overvoltage level of the sending-end power grid to achieve the transient over-voltage suppression target. The simulation example shows that the proposed control method can effectively suppress the transient overvoltage of the sending end grid during commutation failure by coordinating the virtual resistance link with the conventional constant current control.This work is supported by the Science and Technology Project of the Headquarters of the State Grid Corporation of China (No. 52170221000U).