一种抑制连续换相失败的非线性VDCOL控制策略

换相失败是高压直流输电系统(High Voltage Direct Current, HVDC)中常见的故障之一。为了降低连续换相失败发生的概率,提出了一种基于非线性动态VDCOL低压限流控制器(VoltageDependentCurrentOrderLimiter,VDCOL)设计方案。针对常规VDCOL直流电流调节指令灵敏度较低的特点,所设计的非线性动态VDCOL控制策略将系统故障严重程度同时考虑在内,根据电压大小动态调节VDCOL控制器的控制曲线,提高直流电流指令在系统故障期间的响应速度,达到尽快限制直流电流来降低发生连续换相失败概率的目的。在PSCAD/EMTDC仿真环境中,使用国际大电网会议(International Council on Large Electric Systems, CIGRE)标准模型对所提控制方法进行验证。仿真表明,所提非线性动态VDCOL控制器在短路故障时可以抑制连续换相失败,并且有利于快速恢复系统的直流电压和传输功率,保证输电系统正常运行。

A suppression method based on nonlinear VDCOL to mitigate the continuous commutation failure

Commutation failure is one of the most common faults in High Voltage Direct Current (HVDC) transmission system. In order to reduce the probability of commutation failure, a suppression strategy for continuous commutation failure based on nonlinear VDCOL is proposed in this paper. Considering the low sensitivity of DC current command generated by conventional VDCOL, the proposed nonlinear dynamic VDCOL control strategy takes severity of the system failure into account and dynamically adjusts control curve of the VDCOL controller according to voltage level, which improves response speed of the DC current command and limits DC current to reduce the probability of continuous commutation failure. The proposed control method is tested by CIGRE model of HVDC in PSCAD/EMTDC. Simulations show that the proposed nonlinear dynamic VDCOL controller can suppress continuous commutation failure during short circuit fault, and it is beneficial to restore DC voltage and transmission power of the system and ensure the normal operation of HVDC transmission system. This work is supported by the Project of State Grid Hunan Electric Power Company Limited (No. SGTYHT/17-JS-201), the Postdoctoral Innovative Talent Support Program of China (No. BX20180095) and China Postdoctoral Science Foundation (No. 2018M640747).