基于MMC的中压大功率直流配电方案及其控制方法

Scheme and Control Method of MMC Based Medium-voltage and High-power DC Distribution System

为了节省系统的体积,提出了一种新颖的中压直流配电方案,采用模块化多电平换流器(MMC)和二级管不控整流的结构。将MMC的输出交流电压、电流的基波频率设定在1kHz,与传统50Hz控制算法相比,可以在很大程度上减小变流器的体积。由于基波频率的提高,必须简化调制算法,提出了一种MMC方波调制策略,与传统MMC调制算法相比可以节约控制器资源。另外,为了测试整个系统额定运行工况,提出了一种电阻微循环的控制结构,可以实现功率的内部循环,仅从电网吸收电阻消耗的功率和系统的耗散功率,从而可以大大减小电网的压力。

A novel medium voltage DC power distribution scheme is proposed.In order to save the system volume,the structure of modular multilevel converter(MMC)and diode rectifier is used.Compared with the traditional 50 Hz control algorithm,the size of the converter can be greatly reduced by setting the output AC voltage and current base frequency to 1kHz.As the fundamental frequency increases,the modulation algorithm must be simplified.An MMC square wave modulation strategy is proposed,which can save the controller resources compared with the traditional MMC modulation algorithm.In order to test the whole system rated operating conditions,a resistance microcirculation control scheme is proposed.The solution can achieve the internal power cycle,and the grid only provides the power consumption of the resistance and the system power dissipation,which can greatly reduce the pressure of the grid.