级联双极型大容量电池储能系统及其控制策略

Large-capacity cascaded bipolar BESS and its control strategy

针对多储能单元级联的高电压、大容量应用场合,提出一种级联双级型电池储能系统。该系统由AC/DC与DC/DC两级变换器构成,且均采用模块化多电平级联结构,具有结构紧凑、可靠性高、能量控制简单等优点。建立该系统的数学模型并分析其工作原理及约束条件,设计了多电池组荷电状态(SOC)均衡策略,有效解决了电池过充或过放的问题;针对储能系统在不对称运行条件下直流电流波动过大的问题,提出一种直流波动抑制的前馈控制策略。最后,基于RTDS对该系统及控制策略进行数字-物理闭环仿真,验证了系统结构和控制策略的有效性。

A cascaded bipolar BESS（Battery Energy Storage System） is proposed for the high-voltage and large-capacity applications of multiple cascaded energy storage units,which is composed of an AC/DC converter and a DC/DC converter. Both converters adopt the multilevel modular cascading structure,which is compact,highly reliable and simple for energy control. A mathematical model is built for the system,its working principle and constraints are analyzed,and the SOC（State Of Charge） balancing strategy is designed for multiple battery packs to avoid the over-charging and over-discharging. Aiming at the large DC current fluctuation of BESS during its operation in asymmetric eonditions,a feedward control strategy is proposed to smooth the DC current fluctuation. The digital-physical closed-loop simulation based on RTDS verifies the effectiveness of the proposed system structure and control strategies.