送端直流孤岛系统频率限制器优化控制策略

FLC Optimization Control Strategy of Islanded HVDC Sending System

频率限制控制器(frequency limit controller,FLC)作为一种重要的直流有功功率调制手段,可提高交直流混联系统的频率稳定水平,但直流有功功率的调节会改变换流站无功功率水平,进而影响系统电压特性。针对楚穗特高压送端直流孤岛系统,分析了交流系统发生短路故障后,FLC调节有功功率对整流站电压恢复特性的影响机理。在此基础上,提出了基于无功功率变化率的FLC优化控制策略,来提高送端系统的电压稳定性。仿真结果表明,该策略在抑制频率波动的同时,可改善孤岛系统的电压恢复特性。

As a kind of important means for DC active power modulation, frequency limit controller （FLC） can improve the frequency stability level of DC/AC hybrid system. However, DC active power modulation will change the reactive power consumption of converter station, thus affecting the voltage characteristics of system. In allusion to Chuxiong-Suidong UHVDC sending system under islanded operation, this paper analyzes the influence mechanism of DC active power modulation by FLC on the voltage recovery characteristics of rectifier station after the short circuit fault of AC system. On this basis, we propose the optimization control strategy for FLC based on the change rate of reactive power, which can improve the voltage stability of sending system. The simulation results show that this strategy can inhibit frequency fluctuation, while improve the voltage recovery characteristics of islanded system.