采用基数排序算法的MMC优化均压策略

Optimized Voltage Balancing Strategy Based on Radix Sort Algorithm for Modular Multilevel Converter

为了减少模块化多电平变流器MMC在子模块过多时均压控制的排序运算量,同时降低子模块的开关频率,提出了一种采用基数排序算法的MMC优化均压策略。首先分析基数排序算法的原理,指出了在桥臂子模块很多时,将基数排序运用于MMC的均压控制,可以减少排序运算量;其次,根据子模块电容电压的波动允许空间和基数排序算法原理提出了一种优化均压策略,该策略通过减少基数排序中"收集"和"分配"的次数,能进一步减少排序运算量,同时也有效避免了因子模块电容电压发生微小的变化而引起的不必要的开关动作,减少开关频率。仿真分析和实验结果验证了所提出优化均压策略的可行性和高效性。

To reduce the sorting computation load of voltage balancing control for modular multilevel converters(MMCs)with excessive number of sub-modules and the switching frequency of the sub-modules,an optimized voltage balancing strategy is proposed for MMC based on radix sort algorithm.Firstly,the principle of radix sort algorithm is analyzed,and it is pointed out that when there are excessive sub-modules,using radix sort for the voltage balancing control of MMC can reduce the sorting computation load.Secondly,according to the allowable fluctuation range of sub-modules’capacitor voltage and the principle of radix sort algorithm,an optimized voltage balancing strategy is proposed,which can not only reduce the sorting computation by reducing the numbers of"collection"and"distribution"in the sorting process,but also can avoid the unnecessary switching operations resulting from the small changes in sub-modules’capacitor voltage and thus reduce the switching frequency.Simulation and experimental results verified the feasibility and higher efficiency of the proposed optimized voltage balancing strategy.