级联H桥SVG直流侧电压均衡控制策略

DC Side Voltage Balance Control Strategy of Cascaded H-Bridge

传统的级联H桥静止无功补偿器相间电压均衡控制策略分析计算较为复杂,且需要调节PI参数,为此提出了一种无需参数调节的相间电压均衡控制策略。只需排序比较大小,通过查表法即可求出待注入的零序分量,简化了相间电压平衡算法;针对相内电压均衡控制策略,基于伏秒平衡控制原理提出了一种H桥模块作用时间直接修正法,与基于时间计算的载波水平移相调制策略相配合,即使在电压不平衡的暂态过程中也能够完全实现与上层控制的解耦,并且这种方法能够容易地扩展到级联度更高的SVG系统中。最后,通过在Simulink仿真平台与实验室条件下搭建的小功率实验平台验证了算法的有效性与可行性。

In view of the complex analysis and calculation of the traditional cascaded H-bridge SVG interphase voltage balance control strategy and its parameter adjustment,this paper proposes aninterphase voltage balance control strategy that does not need to adjust parameters.The zero-sequence component to be injected can be obtained by the look-up table method,which simplifies the interphase voltage balance algorithm.For the interphase voltage balance control strategy,this paper proposes a direct correction method for the action time of the H-bridge module based on the volt-second balance control principle,which is combined with the time-based calculation CPS-PWM proposed in this paper.The decoupling from the upper-level control can be fully realized even in the transient process of voltage imbalance,which simplifies the innerphase voltage control,and this method can be more easily extended to the SVG system which has more H modules.Finally,the validity and feasibility of the algorithm are verified by the low-power experimental platform built on the Simulink simulation platform and laboratory conditions.