基于谐波状态空间的模块化多电平换流器直流侧改进建模

Modeling for DC Side Impedance of Modular Multilevel Converter Based on Harmonic State Space

目前谐波状态空间方法应用于模块化多电平变流器(modular multilevel converter,MMC)时将控制系统和电气系统的建模统一集成到MMC系统状态空间方程的矩阵A中。该建模方法并没有给出便利的控制系统建模接口,不方便研究控制环节的影响以及不利于模型的扩展。提出了基于谐波状态空间的MMC直流侧闭环阻抗统一建模方法。该建模方法将电气回路与控制回路分别建模表示,控制回路的建模表现为电气状态变量到调制波信号的传递函数矩阵,最后通过调制波信号对电气回路的作用矩阵来实现MMC系统的整体建模。控制回路进行单独建模且并未引入新的变量,使得模型结构更加清晰,并省略了控制系统中多余的状态变量的建模。提出的建模方法还保持了谐波状态空间方法高精度的特点,为MMC的直流侧阻抗分析和参数优化提供了支撑。RT-LAB实时硬件仿真结果验证了所建立模型的正确性。

When the harmonic state space method is applied to a modular multilevel converter(MMC),the modeling of the control system and the electrical system is unified and integrated into the matrix A of the state space equation of the MMC system.This modeling method does not provide a convenient control system modeling interface,which is inconvenient to study the influence of the control link and is not conducive to the expansion of the model.This paper proposes a unified modeling of MMC DC side closed-loop impedance based on the harmonic state space.This method models the electrical loop and the control loop separately.The independent modeling of the control loop does not introduce new variables,and it can still easily analyze the influence of each control link and its parameters on the DC side impedance.The established impedance model has a clear structure,high accuracy,and few variables,which provides support for MMC DC side impedance analysis and parameter optimization.Simulation and experiment verify the accuracy of the established model.