抑制连续换相失败的直流功率控制策略

Research on DC Power Control Strategy for Mitigating Continuous Commutation Failure

连续换相失败的抑制方法是交直流混联系统的关键问题之一,但当前改进直流控制系统乃至换流器拓扑结构的研究方法,未能较好适应现阶段实际工程对控制策略的需求。提出了一种抑制连续换相失败的直流功率控制策略。首先,分析了直流系统的无功需求及连续换相失败的主要原因,提出了基于临界电压的连续换相失败风险判断方法;其次,提出了依据风险预判结果实时减小或恢复直流输送功率的控制策略,以改善直流系统的无功需求和恢复特性,从而抑制连续换相失败;最后,基于标准测试系统和实际电网对文中策略进行了仿真验证,结果表明所提方法具有较好的工程适应性及应用前景。

Method suppressing continuous commutation failure is a vital issue for hybrid AC/DC power systems.However,most existing literatures focus on DC control system and even converter topology,not able to meet the needs of control strategy for actual systems at present.Therefore,a DC power control strategy to cope with continuous commutation failure is proposed in this paper.Firstly,the reactive interaction characteristic of AC/DC system and the main cause of continuous commutation failure are analyzed,and a method for evaluating risk of continuous commutation failure based on critical voltage is proposed.In this control strategy,DC power is reduced or restored in real time in order to improve the reactive power demand and recovery characteristic of the DC system.Finally,the proposed strategy is verified with simulation based on standard test system and actual system.Result shows that the strategy can effectively mitigate the continuous commutation failure,and has fine engineering adaptability and application prospect.