基于MMC铁路功率调节器的环流分析与抑制策略

Circulating Current Analysis and Suppressing Controller Designing of the MMC Based on Railway Static Power Conditioner

采用模块化多电平换流器构造的新型铁路功率调节器(MMC-RPC)实现牵引供电系统电能质量问题综合治理具有诸多优点,但MMC结构特点会导致MMC-RPC存在环流问题。因此通过对牵引供电系统补偿原理的分析,结合MMC-RPC补偿电流特点,建立单相MMC的数学模型,分析了环流产生的机理。在理论分析的基础上,采用比例–积分–复数积分控制器设计了一种适用于MMC-RPC单相系统的环流控制器。最后在Matlab/Simulink中搭建仿真模型,计算与仿真共同验证了MMC-RPC存在偶数倍频环流,其流入直流端会引起直流电流和电压的波动,仿真说明了本文环流控制能策略有效抑制环流。

It has many advantages that using modular multilevel converter based railway static power conditioner （MMC-RPC） to govern the power quality problems of the traction power supplying system. However, the structure topology of MMC-RPC may cause some problems such as circulating current which should be suppressed. Firstly, combined with the compensation characteristics of MMC-RPC and the analysis of the compensation principle of traction power supplying system, the mechanism of the circulating current is analyzed after establishing the mathematical model of the single phase MMC. Secondly, a circulating current suppression controller of the single phase MMC-RPC system is proposed and designed using the proportional-integral-complex integral controller based on the theoretical analysis. Finally, a simulation model is constructed in Matlab/Simulink to validate the effectiveness of the proposed control strategy. Calculation and simulation results both point out that there are even-order circulating current in the single phase MMC-RPC which cause the fluctuations of DC voltage and DC current.