模块化多电平换流器改进简化模型及分析

Improved Simplified Model and Analysis of Modular Multilevel Converter

模块化多电平换流器(MMC)在电平数较多情况下采用等效模型进行电磁暂态仿真对解决仿真效率低问题具重要意义。实际子模块中存在均压电阻,现有建模方法往往对其进行忽略,本文对含均压电阻的受控源桥臂等效模型建模进行改进简化,进一步提高MMC受控源等效模型仿真的精度和效率。方法通过对MMC子模块开关器件以开关状态形式进行简化,基于递推Dommel等值计算方法,降低子模块电容电压更新计算复杂度进而提高仿真效率。并在PSCAD软件进行仿真分析两种常见详细等值模型,为MMC模型选取提供选择依据。

Modular multi-level converter(MMC)adopta equivalent model for electromagnetic transient simulation when there are many levels,which is of great significance to solve the problem of low simulation efficiency.The voltage-sharing resistance exists in the actual submodule,which is often neglected by the existing modeling methods.This paper improves and simplifies the modeling of the equivalent model of the controlled source bridge arm with voltage-sharing resistor,and further improves the MMC controlled source equivalent model Simulation accuracy and efficiency.The method simplifies the switching state of the MMC sub-module switching device,based on the recursive Dommel equivalent calculation method,reduces the calculation complexity of the sub-module capacitor voltage update and improves the simulation efficiency.In PSCAD software,two common detailed equivalence models are simulated and analyzed to provide a basis for selection of MMC models.