摘要
模块化多电平换流器的启动和运行分为不可控预充电、可控预充电和正常运行3个阶段,3个阶段内的子模块电容电压平衡是其安全稳定运行的前提和关键。针对采用载波移相调制的MMC提出一种对3个阶段均适用的新型电容电压平衡方法。在分别研究3个阶段的电容电压不平衡机理的基础上提出基于平均值均压系数的电容电压平衡方法。利用每个子模块电容电压和所在桥臂电压平均值求得均压系数k1i、k2i,根据k1i微调取能电源内MOSFET占空比实现不可控预充电阶段电容电压平衡,根据k2i微调子模块内IGBT占空比实现可控预充电和正常运行阶段电容电压平衡。最后,通过单相3电平MMC实验样机验证所提电压平衡方法的可行性和有效性。
The start-up and operation processes of modular multilevel converter(MMC) are divided into three stages: uncontrollable precharge, controllable precharge and normal operation. The balance of sub-module capacitor voltages in the three stages is premise and key for the safe and stable operation of MMC. A novel capacitor voltages balance method, which is applicable to the three stages, was proposed for the MMC using the carrier phase shift modulation. The dual voltage-sharing coefficients balance method was proposed according to the capacitor voltage imbalance mechanism. Voltage-sharing coefficients k1 i and k2 i were obtained related to the capacitor voltage of each sub-module and the average voltage value of the single bridge arm. The capacitor voltage balancing of the uncontrollable precharge stage was achieved by slightly adjusting the duty cycle of the MOSFET in the self-power supply of the sub-module according to k1 i. And the balance of the controllable and normal operation precharge stage was achieved by slightly turning the duty cycle of the IGBTs in the sub-module according to k2 i. Finally, the feasibility and effectiveness of the proposed method is verified by a single-phase 3 level MMC prototype.
作者
魏新伟
何志兴
徐千鸣
马伏军
罗安
黄旭程
王锋
WEI Xinwei;HE Zhixing;XU Qianming;MA Fujun;LUO An;HUANG Xucheng;WANG Feng(National Electric Power Conversion and Control Engineering Technology Research Center (Hunan University), Changsha 410082,Hunan Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2018年第24期7314-7325,共12页
Proceedings of the CSEE
基金
国家重点研发计划项目(2017YFB0902000)~~
关键词
模块化多电平换流器
电容电压平衡
开关频率
取能电源.
modular multilevel converter (MMC)
capacitor voltage balance
switching frequency
self-power supply
作者简介
魏新伟(1990),男,博士研究生,主要从事链式STATCOM、MMC—HVDC和混杂系统建模研究,1205803198@qq.com;何志兴(1989),男,博士,主要从事FACTS技术研究和电力电子装置的研制,hezhixingmail@163.com。
