MMC-HVDC系统直流侧故障暂态特性分析  

Analysis on Transient Characteristic of DC Transmission Line Fault in MMC Based HVDC Transmission System

作　　者：杨海倩 王玮 荆龙 吴学智 

机构地区：[1]国家能源主动配电网研发中心,北京市海淀区100044

出　　处：《电网技术》2016年第1期40-46,共7页Power System Technology

基　　金：国家能源应用技术研究及工程示范项目(NY20150301)~~

摘　　要：近年来,国内外对模块化多电平换流器(modular multilevel converter,MMC)的研究主要集中于系统建模仿真、控制系统设计等方面。对基于模块化多电平换流器的高压直流输电系统(modular multilevel converter based high voltagedirect current system,MMC-HVDC)直流线路故障的研究也仅是在简单的故障定性仿真分析上。为了比较精确地定量分析MMC-HVDC系统直流侧故障瞬间电气应力的暂态特性、短路故障状态下的等值电路模型,分析了系统直流侧故障的机理,给出了故障电压、电流的数学表达式。基于RT-LAB软件搭建了双端MMC-HVDC仿真模型,验证了故障暂态特性分析的结果,单极接地故障使得直流非故障极的对地电压与换流站交流侧的相电压增大;双极短路故障会引起换流站的桥臂产生严重的过电流现象;单极断线故障会导致整流站很大的直流电压变化率,引起严重直流过电压。针对上述问题,文章结合分析结果给出了相应的故障保护要求和策略。In recent years, research on modular multilevel converter（MMC） mainly focuses on system modeling and simulation and design of control system both in China and abroad. Research on DC line fault of MMC based HVDC system is only in simple qualitative simulation analysis. In order to quantitatively analyze transient characteristics of electrical stress in DC side of MMC-HVDC system more accurately, equivalent circuit models of DC transmission line breaking fault, monopolar grounding fault and pole-to-pole fault are established respectively. Mechanism of DC side fault is analyzed, and mathematical expression of fault voltage and current is deduced. A 2-terminal MMC-HVDC system is established in RT-LAB and simulation results of fault transient analysis are verified. Monopolar grounding fault makes non-fault pole to ground voltage and phase voltage of AC side of converter station increase. Pole-to-pole fault will cause overcurrent in converter bridge arm. Line breaking fault will lead to large DC voltage change rate in rectifier stations, causing serious DC overvoltage. Aiming at above problems, corresponding protection requirements and strategies of faults are put forward based on analysis results.

关 键 词：MMC-HVDC 直流侧故障 暂态特性分析 等值电路模型 故障保护策略 

分 类 号：TM721.1[电气工程—电力系统及自动化]