级联STATCOM直流侧电压平衡控制方法

Balancing control method of DC voltage of cascaded H-bridge STATCOM

针对级联静止同步补偿器直流侧电容电压不平衡的问题,提出一种基于相移载波调制的直流侧电压平衡方法。该方法根据各个直流侧电压变化趋势来进行有选择的交换脉冲,将直流电压高于平均值且变高的模块的驱动信号与直流电压低于平均值且变低的模块的驱动信号交换,以载波相位差造成的直流侧不平衡来补偿开关损耗等造成的不平衡。该方法将直流侧平衡和静止同步补偿系统控制分开,算法简单,省略了直流侧辅助直流电源,使H桥模块更加简单,节省了成本。通过仿真分析和实验结果证实了该方法的正确性、有效性和实用性。

This paper presents a control strategy to balance the DC capacitor voltage for cascaded H-Bridge multilevel static synchronil compensator（STATCOM） based on phase-shifted carrier pulse width modulation.Choosing pulse transposition is adopted according to the trend of each DC voltage.Exchanging the driving signals of the module whose DC voltage is increasing and higher than the average with the driving signals of the module whose DC voltage is decreasing and lower than the average.The unbalance of the DC side caused by the switching loss and other losses could compensate the unbalance caused by the carrier phase shifted PWM.Control algorithm is simple since the balancing method separated the DC capacitor voltages balancing control from STATCOM control system.This new control method has the advantages of non-auxiliary DC power,simplifying H bridge module and lower cost.Simulation analysis and results prove its validity and utility.