基于触发角偏差补偿的连续换相失败抑制措施

逆变侧交流系统发生不对称故障后容易导致连续换相失败，威胁电网的安全稳定运行。针对这一问题，基于不对称故障后直流控制系统的响应规律，根据直流系统稳态运行曲线将故障及恢复过程分为2个阶段，发现在阶段2即故障稳定恢复阶段，存在换相面积需求量逐渐增加而换相面积最大提供量逐渐减小的趋势，并且在此过程中触发角指令值与触发角实际值还存在偏差，触发角偏差将进一步削减换相面积最大提供量，是引发连续换相失败的重要原因。基于此，分析了触发角偏差的来源以及触发角偏差对控制系统的影响，提出一种基于触发角偏差补偿的连续换相失败抑制措施，并在PSCAD/EMTDC中基于CIGRE HVDC标准模型进行仿真验证。仿真结果表明，所提措施能够有效抑制连续换相失败。

Continuous commutation failure suppression strategy based on firing angle deviation compensation

After the asymmetrical fault occurs in the alternating current(AC) system on the inverter side, it is easy to cause continuous commutation failure, which threatens the safe and stable operation of the grid. In order to solve this problem, based on the response law of the high voltage direct current(HVDC) control system after an asymmetric fault, the fault and recovery process is divided into two stages according to the steady-state operation curve of the HVDC system. There is a trend that the commutation area demand gradually increases and the maximum supply of commutation area gradually decreases in Stage2, i. e. steady fault recovery stage. There is still a deviation between the command value and the actual value of the firing angle during this process, and the deviation of the firing angle will further reduce the maximum supply of the commutation area, which is an important cause of continuous commutation failure. Based on this, the source of firing angle deviation and the influence of firing angle deviation on the HVDC control system are analyzed, and a continuous commutation failure suppression measure based on firing angle deviation compensation is proposed and verified based on the CIGRE HVDC benchmark model in PSCAD/EMTDC. The simulative results show that the proposed measures can effectively suppress the continuous commutation failure.