改进SOC下垂控制的分布式储能系统负荷电流分配方法

Load Current Sharing Method of Distributed Energy Storage Systems by Improved SOC Drooping Control

随着分布式发电及直流微电网的快速发展,分布式储能得到学者们的广泛关注。文中针对分布式储能系统中储能单元荷电状态(state-of-charge,SOC)的随机性以及变化缓慢的特点,在储能单元充电和放电过程中采用改进的SOC幂指数下垂控制策略。SOC的幂函数可提高SOC分辨率,SOC指数函数下垂曲线平滑且没有间断点,改进的SOC幂指数下垂控制有利于寻找最优下垂曲线使系统快速收敛到均衡状态。由于下垂控制对系统的稳定性有影响,为此文中给出了用于分析系统稳定性的特征方程和系统控制结构图,由劳斯稳定判据结合直流母线电压跌落范围验证了系统的稳定性。通过由2台储能单元组成的实验平台,验证了所提下垂控制策略的可行性,负荷能够按容量快速分配,且能够快速收敛到均衡状态。

With the development of distributed generation and DC micro grid, distributed energy storage system has drawn more attention recently. Considering that characteristics of randomness and slow change of the state-of-charge （SOC） of energy storage unit in distributed storage system, this paper proposed the control strategy of SOC power exponent drooping, that is, during the energy storage unit charging and discharging , using SOC power exponent drooping control strategy to improve the resolution of SOC, the drooping curve is smooth and no discontinuous point, improved SOC power exponent is helpful to find the optimal drooping curve make the system quickly converge to identical state. Considering the droop control has an effect on the stability of the system, this paper presented the characteristic equation and the control block diagram of the system, by stable law criterion combining with DC bus voltage drop range verify the stability of the system. The experimental prototype with two storage modules was realized, the stability analysis and the results of experiments were used to validate the proposed droop control method, the drooping coefficients of the SOC power exponent make the system fast converges to identical state and fast distribution of the load current.