一种MMC型VSC-HVDC系统预充电的控制策略  

A Pre-charging Control Strategy for Modular Multilevel Converter Based VSC-HVDC System

作　　者：姜燕[1] 胡敬伟 王辉[1] 叶虹志 罗婉韵 曾毅[2] 

机构地区：[1]湖南大学电力推进与伺服传动教育部重点实验室,湖南长沙410082 [2]湘电集团有限公司海上风力发电技术与检测国家重点实验室,湖南湘潭411101

出　　处：《控制工程》2014年第1期41-45,48,共6页Control Engineering of China

基　　金：国家重点基础研究发展计划(973计划)项目(2010CB736201);国家国际科技合作项目(2011DFA62240);湖南省国际科技合作项目(2011WK2012)

摘　　要：模块化多电平换流器(Modular Multilevel Converter,MMC)是一种新型的电压源换流器拓扑,很适合于柔性直流输电(Voltage Source Converter Topology Applied in Voltage Source Converter-high Voltage Direct Current,VSC-HVDC)场合。在系统正常运行之前,MMC中的电容需进行预充电操作,以建立额定的电容电压和直流母线电压。首先介绍了传统启动方式存在的缺陷,为弥补这些不足,结合MMC启动时的数学模型,在详细分析换流器电容预充电动态过程的基础上,采用载波移相(Carrier Phase Shifted Modulation,CPSM)策略提出了一种适用于MMC可控阶段的新型启动方法。设计了电容电压参考值给定方式、内环电流控制以及外环电压控制,该预充电策略在限制过电流和避免过电压的同时,兼顾启动的速度和效率,提高了柔性直流输电系统启动的快速性和可靠性。由在Matlab/Simulink中所构建模型的仿真结果可以看出,所提出的控制策略正确、有效。Modular multilevel converter（MMC） is a novel VSC-HVDC. The capacitor contained in MMC needs to be pre-charged before the normal operation of the system, to reach the rated capacitor and DC bus voltage value ultimately. Shortcomings of traditional starting mode are introduced first. In order to make up for the deficiency, on the basis of a detailed analysis of the pre-charging dynamic process of the capacitors in the converter and mathematical model of MMC, a starting strategy fit for MMC controlled stage is presented by CPSM in this paper. Capacitor voltage reference value, inner loop current control and outer loop voltage control are designed. Over current is limited and over voltage is avoided, moreover, the speed and efficiency of pre-charging process are also considered, raising the rapid and stability of VSC-HVDC system. From the results of the simulation model built in Matlab/Simulink, the correctness and validity of the control strategy is certified.

关 键 词：柔性直流输电 模块化多电平换流器 预充电 控制策略 

分 类 号：TM46[电气工程—电器]