基于RTDS的模块化多电平换流器子模块等效模型

摘要

采用模块化多电平换流器(MMC)的高压直流输电是目前最具前景的直流输电方式.MMC系统需要大量的子模块串联,这给实时仿真带来巨大挑战.文中在实时数字仿真仪(RTDS)中采用CBuilder建立了自定义子模块rtds_SM,不仅能够减少RTDS仿真中MMC子模块的占用资源,还能解决已有的MMC封装模块不能用于研究MMC系统子模块发生故障的特性及其控制保护策略的问题.对子模块中的绝缘栅双极型晶体管(IGBT)、反并联二极管、电容进行建模,实现了用于子模块控制和保护的旁路开关以及旁路晶闸管模型.所建立的rtds_SM具有8个输入和2个输出,能反映子模块的各种运行工况以及子模块的电容均压控制.仿真结果表明,提出的MMC子模块模型占用仿真资源小且仿真精度高.%Modular multilevel converter (MMC) is one of the most promising direct current transmission modes.There are lots of sub-modules (SM) in series in MMC high-voltage direct-current (MMC-HVDC) transmission system.It is a challenge to model MMC-HVDC system in real-time simulation tools.Furthermore,the existing MMC component in real time digital simulator (RTDS) cannot be used for SM faults.The rtds_SM component is proposed.It is developed by CBuilder in RTDS.The component can not only reduce memory usage in RTDS,but also be used for the sub-module fault and the test of control and protection devices for MMC system in RTDS.The insulated gate bipolar transistor (IGBT),antiparallel-connected diode and capacitor are modeled; the bypass switch and thyristor models are realized for control and protection.The developed rtds_SM component has eight inputs and two outputs,which can response for various operation states under various conditions.It can also provide the information for capacitor voltage balancing.Simulation results show that the proposed rtds_SM component needs less memory usage and provides high enough simulation precision.