模块化多电平换流器电容电压的分布式均衡控制方法

Distributed Balancing Control Strategy of Capacitor Voltage for Modular Multilevel Converter

子模块电容电压的均衡控制是模块化多电平换流器(MMC)的关键问题,通常的做法是在中心控制器通过排序法或附加控制量法集中实现电容电压的均衡控制,当级联的子模块数目巨大时,中心控制器存在占用计算资源过多甚至难以实现的问题。提出一种MMC子模块电容电压的分布式均衡控制方法,将电容电压的均衡控制环分散到各子模块控制器中实现,每个子模块控制器仅需要完成自身电容电压追踪桥臂电容电压平均值的控制,均衡控制环简单且占用计算资源小,当级联的子模块数目大幅增加时,中心控制器的计算资源变化较小。通过对基于MMC的双端柔性直流输电系统的RT-LAB仿真结果和物理试验结果验证了所提出的分布式均衡控制方法的正确性和有效性。

The sub-module capacitor voltage balancing control is a key issue for the modular multilevel converter（MMC）.To date,balancing control is usually based on sorting the sub-module capacitor voltage or adding an additional control variable to each sub-module reference voltage.When the number of levels is very large,the central controller may have the problem of asking for too many computational resources to be gratified.So a distributed balancing control strategy of capacitor voltage for MMC is proposed.by implementing the balancing control loop for sub-modules in its local controller.The balancing control loop is very simple and the computational resource required is very small.The increase in the number of levels has very slight effect on the required computational resource of the central controller.The feasibility of the proposed balancing strategy is verified using the RT-LAB simulation results and experimental results.