基于MMC双向DC-DC变换器的超级电容储能系统控制策略分析与设计

Analysis and Design of Control Strategy for MMC-BDC Based Ultra-capacitors Energy Storage Systems

研究一种基于多模块多电平双向DC-DC变换器的超级电容储能系统,该系统可有助于减小超级电容单体电压低与应用场合电压高间的矛盾。超级电容组间的均压控制是该系统稳定运行的关键之一。对超级电容组的均压控制和储能系统能量管理策略进行分析和设计。利用双向变换器的小信号模型分析超级电容储能系统电流控制与超级电容组间均压控制的关系,设计多模块多电平双向DC-DC变换器的双闭环控制策略,在稳定控制网侧电感电流的同时实现超级电容组间电压均衡的解耦控制。进一步,根据母线电压变化及超级电容荷电水平(state of charge,SOC)提出储能系统能量控制策略。系统仿真和实验验证了所提出的基于MMC双向变换器的超级电容储能系统控制策略的有效性。

A novel energy storage system （ESS） with ultra-capacitors, which based on modular multilevel bidirectional DC/DC converter, was discussed. The inconsonance of low monomer voltage rating of the ultra-capacitors and the high voltage applications can be mitigated in this system. The voltage equalization of ultra-capacitors is critical for stable operation of the system. The inherent relationships between the system current control and the ultra-capacitors voltage sharing were analyzed and a double closed-loop control strategy for the MMC-BDC based ESS was proposed, which decouples the system current control and the ultra-capacitors voltage sharing control. Furthermore, the energy management strategy which is based on the DC bus voltage and the state-of-charge （SOC） of the ultra-capacitors was also proposed. The effectiveness of the proposed control strategies for the MMC-BDC based ultra-capacitors ESS was validated with the simulations and the experimental results.