基于模块化多电平换流器的电池储能系统控制策略

针对基于模块化多电平换流器的电池储能系统,提出了电网电压对称运行和电网电压不对称运行情况的通用控制策略。其控制策略主要包括输出功率控制、电池荷电状态(SOC)均衡控制以及并网电流直流分量抑制。SOC均衡控制分为相间SOC均衡、桥臂间SOC均衡以及桥臂内SOC均衡。通过控制环流实现相间SOC均衡和桥臂间SOC均衡;通过调节各个子模块输出电压工频分量,实现桥臂内各子模块的SOC均衡。首先对基于模块化多电平换流器的电池储能系统的模型进行了详细分析;基于等效模型,提出了相应的控制策略。最后,通过仿真以及实验对所提出的控制策略进行了验证。

Control Strategy for Battery Energy Storage System Based on Modular Multilevel Converters

A control strategy for battery energy storage system based on modular multilevel converter(MMC)is proposed, which is applicable for the operation under both symmetrical and asymmetrical grid voltage conditions. It contains the control of output power, balance of state of charge(SOC)and elimination of DC output current. The battery SOC balancing control contains the SOC balancing among three phases, between arms and within each arm. The SOC balancing control methods among three phases and between arms are implemented by controlling the circulating currents. The SOC balancing control method within each arm is implemented by modifying the fundamental frequency component of the sub-module output voltage. The basic operational principles have been analyzed in detail and the control strategy has been designed accordingly. Finally, the proposed theories are verified through the MATLAB simulations and a scaled down experimental prototype.