模块化多电平换流器子模块故障特性和冗余保护
Redundancy Protection for Sub-module Faults in Modular Multilevel Converter
-
摘要: 对模块化多电平换流器(MMC)的基本工作原理进行了阐述,分析了MMC中子模块的几种常见故障原因,指出了单个子模块故障会引发直流电压和直流电流的振荡,最终将导致换流器停运。对级联H桥多电平换流器几种常见的子模块故障冗余保护方案进行了比较,在此基础上提出了适合MMC的子模块故障冗余保护方法。该方法将少量冗余子模块置于热备用状态,这些热备用冗余子模块能够以最快的速度接入桥臂来替换故障子模块。其余冗余子模块被置于冷备用的闭锁状态,能够可靠保护绝缘栅双极晶体管(IGBT)中没有电流流过。时域仿真结果表明,所提出的保护方法可以避免单个子模块故障而造成换流器停运,并能够让换流器快速恢复正常工作。Abstract: The operation mechanism of modular multilevel converter（MMC） is described.Different kinds of sub-module faults in MMC are analyzed,which may cause the oscillations of DC voltage and current and finally cause the outage of the converter.Different redundancy protection methods（RPMs） to deal with sub-module faults in cascaded H-bridge converter are compared,and then a new RPM suitable for sub-module faults in MMC is proposed.In this method,one or few redundant sub-modules are put in hot stand-by state in order to replace fault sub-module rapidly,while the others are in cold stand-by blocking state so as to protect the insulated gate bipolar translators（IGBTs） from current flowing in them.Time-domain simulation results show that the proposed RPM enables MMC based voltage source converter based high voltage direct current（VSC-HVDC） system to recover from sub-module faults without interruptions of power delivery.
下载:
