模块化多电平型内嵌式直流潮流控制器及其控制策略

An Embedded DC Power Flow Controller Based on Modular Multilevel Converter and Its Control Strategy

由于柔性直流系统易于多点馈入、多端成网从而解决控制灵活性及供电可靠性等问题,网状柔性直流输电系统正获得越来越多的关注与研究。解决网状直流系统中由于线路数大于等于可控节点个数时潮流不可控的问题,需增加直流潮流控制器以实现线路优化运行,达到输电走廊堵塞缓解及线损减少的目的。为满足高压柔直输电网的潮流控制需求,针对模块化多电平换流器(modular multilevel converter,MMC),文中提出一种新型内嵌于MMC换流器的直流潮流控制器(embedded DC power flow controller,e-DCPFC),采用模块化多电平结构,具有宽范围、模块化等优势。首先基于MMC型e-DCPFC的拓扑结构,分析工作原理并建立其数学模型,提出系统控制策略。最后,通过仿真与小功率样机,验证e-DCPFC潮流控制的可行性及有效性。

Flexible DC systems is convenient to solve the problem of flexible control and reliable power supply through multi-point feed-in method and multi-terminal networks. For the long transmission distance and flexible control strategy, concerns and research about mesh-type high voltage multi-terminal flexible DC technology have been greatly increased. DC power flow controller(DCPFC) can realize optimal power flow control, so as to relieve the congestion of transmission corridor and reduce the line loss. Specific to high voltage multi-terminal flexible DC network with modular multilevel converter(MMC), this paper presented an embedded DC power flow controller(e-DCPFC) embedded in MMC, with which power flow control capability for flexible DC grids could be realized. It had the advantages of high voltage level, few switching devices, no filter and simple structure. First, based on the topology of e-DCPFC, the detailed analysis of the working principle of e-DCPFC, the coordinated control strategy for e-DCPFC and MMC were proposed. Finally, a simulation model and a prototype of e-DCPFC were built for verification.