直流微电网中双向储能变换器的二次纹波电流抑制与不均衡控制策略

Secondary Ripple Current Suppression and Imbalance Control Strategy in Bidirectional Storage Converter of DC Microgrid

交流负载大规模接入直流微电网会通过逆变器引入大量的2次纹波电流到直流母线上,进而通过双向储能变换器传导至储能系统侧,严重影响储能电池和电力电子器件的寿命。提出一种直流微电网中双向储能变换器的2次纹波电流抑制与不均衡控制策略,通过带通滤波器(band pass filter,BPF)在2倍基频处引入虚拟阻抗,以改善对2次纹波电流的不均衡控制;由于增加了双向储能变换器在2倍基频处的等效输出阻抗,2次纹波电流将大部分从滤波电容回流,使得2次纹波电流不能或者很少一部分可以传导至储能系统侧,可以有效避免2次纹波电流对储能电池的不利影响。仿真与实验结果都表明了该控制策略的有效性和合理性。

Large scale integration of AC load to DC microgridintroduces lots of secondary ripple current to DC bus via inverter, and secondary ripple current will transfer to storage system side through bidirectional energy storage converter, thus seriously affecting energy storage battery and service life of electronic devices. This paper presented a secondary ripple current suppression and imbalance control strategy in bidirectional storage converter of DC microgrid. Virtual impedance was introduced at twice fundamental frequency through band pass filter to improve imbalance control of secondary ripple current. Due to increase of equivalent output impedance in bidirectional storage converter at that frequency, most of secondary ripple current would flow back through filter capacitor, so that no or few secondary ripple current would be transmitted to energy storage system side, effectively eliminating adverse effects of secondary ripple current on storage batteries. Simulation and experiment results show that the control strategy is effective and reasonable.