基于虚拟阻抗的MMC交、直流侧故障过电流抑制方法  

Over Current Suppression Control for AC and DC Faults of Modular Multilevel Converters Based on Virtual Impedance

作　　者：张帆 许建中 苑宾 赵成勇 

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市昌平区102206

出　　处：《中国电机工程学报》2016年第8期2103-2113,共11页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51177042);国家863高技术基金项目(2013AA050105);中央高校基本科研业务费项目(2014XS07)~~

摘　　要：模块化多电平换流器(modular multilevel converter,MMC)适用于高压大容量柔性直流输电。MMC-HVDC系统交、直流侧发生故障时产生的过电流直接影响着IGBT等电力电子器件的选型及系统安全运行,基于虚拟阻抗的过电流抑制策略可以有效对故障过电流进行抑制,且不影响系统的稳态运行。分别对MMC直流、交流侧故障产生的过电流机理进行分析,得出了不同电路参数对于过电流程度的影响;提出了基于虚拟阻抗的过电流抑制策略,基于通用的双闭环矢量控制策略,通过将实际电路元件的特性映射入控制系统以达到抑制故障过电流的目的;同时提出了系统故障过电流的评价指标;最后,基于PSCAD/EMTDC搭建了双端11电平仿真模型,仿真结果验证了基于虚拟阻抗的过电流抑制策略的有效性。Modular multilevel converter（MMC） has shown its significant prospects on VSC-HVDC with great power capacity. DC and AC faults cause the over current in the arms, which affect the selection of IGBTs and the safety of the whole MMC-HVDC system directly. Over current suppression control based on virtual impedance can significantly reduce the over current level without affecting the steady state operation. Both the AC and DC faults mechanism were analyzed. Relations between the circuit parameters and the over current level were derived. According to the result of derivation, characteristics of AC and DC outlet impedance were mathematically mapped to the control scheme respectively, added to the vector current controller. Evaluation indexes both in average and transient were proposed to measure the effect of the over current suppression control. Time-domain simulation studies based on PSCAD/EMTDC were performed to verify the proposed control scheme. It shows that the added control scheme based on virtual impedance can significantly reduce the over current level.

关 键 词：模块化多电平换流器 直流侧故障 交流侧故障 虚拟阻抗 过电流抑制 

分 类 号：TM72[电气工程—电力系统及自动化]