柔性直流电网紧急限流控制策略研究  

Research on the Emergency Current-Limiting Control in VSC-HVDC Grid

作　　者：倪斌业 向往[1] 周猛[1] 左文平[1] 蔡普成 文劲宇[1] NI Binye;XIANG Wang;ZHOU Meng;ZUO Wenping;CAI Pucheng;WEN Jinyu(State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology),Wuhan 430074,Hubei Province,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《中国电机工程学报》2020年第11期3527-3536,共10页Proceedings of the CSEE

基　　金：国家自然科学基金项目(U1766211,51807071)。

摘　　要：柔性直流电网对高速大容量直流断路器的需求限制了其发展和应用。基于混合型模块化多电平换流器(modular multi-level converter,MMC)的限流控制方案受限于拓扑结构,不适用于广泛采用的半桥型MMC柔直工程。该文提出了一种具有拓扑结构通用性与故障类型通用性的紧急限流控制策略,能够降低直流断路器(DC circuit breaker,DCCB)的开断电流和耗散能量。该文首先介绍了紧急限流控制的原理以及其与DCCB的协调策略,分析并推导了限流控制作用下故障电流的计算方程;研究了限流控制不同投入时刻对故障电流发展的影响;最后在基于半桥型MMC的四端直流电网中进行了仿真验证。仿真结果表明:紧急限流控制使得DCCB的开断电流减小了4.29kA(40.74%),耗散能量减小了23.4MJ(60.47%),并且适用于高阻性故障。The requirement for the high-speed and large-capacity DC circuit breaker(DCCB)hampers the development and application of the modular multi-level converter high voltage direct current(MMC-HVDC)grid.The current-limiting schemes based on hybrid MMC are restricted by the particular topology,and thus are not suitable for existing systems based on half-bridge MMC.This paper proposed an emergency current-limiting control scheme with generality of submodule topologies and fault types,which can reduce the breaking current and absorbed energy of the DCCB.The principle of the emergency current-limiting control,together with its coordination strategy with DCCB,were firstly introduced.The calculating equations of fault currents under current-limiting control were derived.The influence of the different switching time on the development of the fault current was studied.Eventually,the four-terminal DC grid based on half-bridge MMC was simulated.The simulation results show that the proposed current-limiting control can not only reduce breaking current and absorbed energy of the DCCB by 4.29kA(40.74%)and 23.4MJ(60.47%),respectively,but also can be suitable for high-resistance fault.

关 键 词：直流电网 模块化多电平变流器高压直流输电 半桥型MMC 限流控制 直流断路器 

分 类 号：TM76[电气工程—电力系统及自动化]