适用于混合级联直流输电系统的柔直换流器直流侧控制方法  

DC side control method of modular multilevel converter for hybrid cascaded ultra high voltage DC transmission system

作　　者：随顺科 常昊添 邹强[1] 李钢[1] 卢宇[1] SUI Shunke;CHANG Haotian;ZOU Qiang;LI Gang;LU Yu(NR Electric Co.,Ltd,Nanjing 211102)

机构地区：[1]南京南瑞继保电气有限公司,南京211102

出　　处：《电气技术》2023年第4期57-62,共6页Electrical Engineering

基　　金：国家电网有限公司总部科技项目(5200-202156078A-0-0-00)。

摘　　要：针对高低阀级联组成的特高压混合直流输电系统,提出一种适用于柔直换流器的直流电压控制方法。在选取单个柔直换流器作为定直流电压控制模式的基础上,其余定功率控制换流器加入分级辅助电压控制,稳态时精准控制直流功率,动态时针对不同电压波动,分级投入电压辅助控制,快速平抑直流过电压、欠电压和长时振荡问题。在此基础上,级联结构中的多柔直换流器直流侧不经平波电抗而直接并联,为避免多换流器间振荡,加入直流阻尼控制方法。最后利用实时数字仿真(RTDS)系统搭建级联直流系统仿真模型,仿真结果验证了所提方法的正确性和有效性。For the hybrid cascaded ultra-high voltage direct current(UHVDC)transmission system composed of high and low valve,a DC voltage method suitable for modular multilevel converter(MMC)is proposed.Based on selecting a single MMC as a constant DC voltage control mode,the other power-controlled converters are added with graded auxiliary voltage control,which can accurately control DC power in steady state,and put in voltage auxiliary control in different stages according to different voltage fluctuations in dynamic state,the problems of DC over-voltage,under-voltage and long-term oscillation can be quickly suppressed.On this basis,the DC side of the multi-converters in the cascade structure is directly connected in parallel without smoothing reactor reactance,and to avoid the oscillation among the multi-converters,a DC damping control method is added.Finally,a simulation model of cascaded UHVDC transmission system is built using the real time digital simulator(RTDS)and simulation results demonstrate the correctness and validity of the proposed method.

关 键 词：混合级联直流输电 柔直换流器 直流电压控制 分级辅助电压控制 直流阻尼 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM46