注入无功功率的链式电池储能系统荷电状态均衡控制策略

针对链式电池储能系统相内电池组荷电状态(SOC)不均衡问题,分析了单位功率因数下均衡控制策略在SOC极度不均衡时导致过调制的边界条件,并提出了一种注入无功功率的新型相内SOC均衡控制策略。通过在各H桥调制信号中叠加有功和无功电压分量,重新分配有功和无功功率,保证SOC处于极端状态的电池组主要进行有功功率交换,其余电池组主要进行无功功率交换,实现极端模块调制比有效降低,非极端模块调制比略有增长,避免过调制。与单位功率因数均衡控制策略相比,该策略通过控制功率因数角充分协调各模块调制比,可以在各电池组SOC差异更大的情况下实现均衡控制,扩大适用范围。仿真结果验证了所提策略的正确性和有效性。

Balancing Control Strategy of State of Charge for Cascaded Battery Energy Storage System with Injection of Reactive Power

To address the issue of state of charge (SOC) unbalance in cascaded battery energy storage system, this paper analyzes the boundary conditions of over-modulation with unity power factor for balancing control strategy when SOC is extremely unbalanced, and proposes a novel balancing control strategy of SOC in phase with injection of reactive power. By superimposing the active and reactive voltage components to each H-bridge modulation signal and redistributing active power and reactive power, this strategy can ensure that the batteries with extreme SOC mainly exchange active power, while other batteries mainly exchange reactive power. Therefore, it can effectively reduce the modulation ratio of the batteries with extreme SOC, while slightly increase the modulation ratio of other batteries, and avoid over-modulation. Compared with the balancing control strategy with unity power factor, this strategy can fully coordinate the modulation ratio of each module by controlling the power factor angle and expand application scope of balancing control with bigger difference between SOC of each battery. The simulation results verify the correctness and effectiveness of the proposed control strategy.