模块化多电平换流器的电容电压均衡优化控制策略

CAPACITOR VOLTAGE BALANCE OPTIMIZATION CONTROL STRATEGY FOR MODULAR MULTILEVEL CONVERTER

针对传统模块化多电平换流器(MMC)电容电压均衡策略计算量大、开关频率高的问题,提出一种优化的电容电压均衡控制策略,以待排子模块电容电压序列的中位值作为基准值,进行比较递归得到投入组与切除组模块信息,减少排序过程的比较次数;同时,设置子模块电容电压离散度阈值,在子模块电容电压一致性允许的前提下减少子模块非必要的频繁投切,降低开关频率。最后,在Matlab/Simulink中搭建MMC仿真模型,验证所提策略的可行性和有效性。

Aiming at the large amount of calculation and high switching frequency of the traditional capacitor voltage balancing strategy of modular multilevel converter,an optimized capacitor voltage balancing control strategy is proposed.Taking the median value of capacitor voltage series of sub-module as reference value,sub-modules information of the ongroup and the off-group are obtained by comparison and recursion,and the comparison times of the sorting process are reduced. At the same time,the threshold of capacitor voltage dispersion of sub-module is set up,which reduces the unnecessarily frequent switching of sub-modules and the switching frequency under the premise of the sub-modules capacitor voltage consistency. Finally,a MMC simulation model is built on Matlab/Simulink to verify the feasibility and effectiveness of the proposed strategy.