多端口线间直流潮流控制器及控制策略优化

Multiport Interline DC Power Flow Controller and Control Strategy Optimization

针对目前的线间直流潮流控制器大多仅能控制1条线路的潮流以及难以拓展的问题,提出一种基于MMC的多端口线间直流潮流控制器(multiportinterlineDCPowerflow controller,MI-PFC)。首先,分析安装多端口DCPFC的必要性,并提出MI-PFC的拓扑结构,将其划分为直流通路和交流通路;其次,详细分析该直流潮流控制器的工作原理,主要包括潮流控制和自身功率平衡,基于此设计MI-PFC控制策略,并以桥臂电压差值最小为目标对控制策略进行优化;最后,在PSCAD/EMTDC仿真软件中搭建四端柔性直流电网,通过MI-PFC启动、控制策略对比和某一换流站功率跌落3种工况,验证MI-PFC能够控制多条线路潮流、无需预充电以及具有良好的动态响应能力。

Aiming at the problem that most of interline DC power flow controllers can only control the power flow of one line and are difficult to expand,a multiport interline DC power flow controller(MI-PFC)model based on modular multilevel converters was proposed.Firstly,the necessity of installing multiport DCPFC was analyzed.The topology of MI-PFC was proposed,which was divided into DC path and AC path.Secondly,the principle of the proposed DC power flow controller was analyzed in detail,including analysis on power flow control method and internal power balance.Based on this,the control strategy of the proposed MI-PFC was designed,to minimize the voltage difference between bridge arms.Finally,a four-terminal DC grid was built in PSCAD/EMTDC to verify the effectiveness of the proposed topology and control strategy.Based on the comparison of MI-PFC start-up,control strategy and power drop of one voltage source converter,it was verified that the proposed MI-PFC can control multiline power flows with good dynamic response ability and avoiding pre-charging.