基于实时数字仿真器的模块化多电平换流器内部故障混合仿真模型

Hybrid Simulation Model of Modular Multilevel Converter Internal Fault Based on Real-Time Digital Simulator

高电压模块化多电平换流器(MMC)中大量子模块级联给实时仿真带来了极大的挑战。通过对桥臂或换流器进行封装等效可以提高MMC仿真系统的计算效率,但高度封装化的模型给换流器内部故障的仿真造成了困难。相比于离线仿真软件,实时数字仿真器(RTDS)对模型计算速度和效率的要求更高,而且由于不能进行插值,对电力电子器件的模拟较为困难。为了兼顾实时仿真对故障仿真功能和模型计算效率的双重需求,该文采用详细等效和简化等效相结合的混合仿真方法,利用CBuilder工具开发了一种适用于RTDS的具备内部故障仿真功能的MMC桥臂混合仿真模型。该模型避免了不同类型仿真模型间一个步长的延时问题,不仅能够快速仿真大规模MMC系统,还能够模拟多种换流器内部故障。在RTDS中搭建单端MMC系统,验证了所提模型的精确性和有效性。

A large number of series-connected submodules in a high-voltage modular multilevel converter(MMC)system introduce a great challenge for real-time simulation.Though the simulation efficiency of the MMC model can be improved by encapsulating equivalent model of the bridge arm or the converter,the internal fault of the converter fails to be simulated by using existing encapsulated equivalent model.Compared with off-line simulation tool,the interpolation calculation method cannot be utilized in real-time digital simulator(RTDS),it is more difficult to simulate power electronic devices,and has higher requirements on calculation speed and efficiency.To enhance the calculation effectiveness while keeping the precision under various fault situation,a hybrid simulation model of MMC arm combining the detailed and simplified equivalent models is proposed,which is implemented by utilizing CBuilder in RTDS.The proposed model can be conveniently used to simulate various internal faults of converters,bridge arms,and submodules with real-time calculation.The calculation precision and effectiveness of the proposed model are verified in RTDS.