直流微电网储能荷电状态协调控制

Coordinated control of energy storage state of charge in DC microgrids

储能系统采用串并联结构(串联的储能单元为一组,多组并联)可以实现将小容量、低电压等级的储能单元接入直流微电网中,并且可以实现系统扩容和提高端电压。为避免串并联结构的储能单元因荷电状态(state of charge,SOC)和额定容量差别导致个别储能单元提前退运的短板效应,提出一种考虑储能SOC和额定容量的控制方法,实现串联模块间的电压和并联模块间的功率合理分配。考虑到功率分配后期因储能单元间SOC差别较小导致均衡速度较慢的问题,引入变异系数对下垂系数进行动态优化。考虑到升压或扩容导致各组总容量不同,引入容量权重因子,使储能单元达到均衡出力。通过搭建MATLAB/Simulink仿真模型,验证了策略的可行性。

The energy storage system adopts a series-parallel structure(one series of energy storage units,multiple groups in parallel)to connect small-capacity,low-voltage levels of energy storage unit to the DC microgrids,and it can achieve system expansion and the increase of terminal voltage.In order to avoid the short-board effect of individual energy storage units being returned early due to the difference in state of charge(SOC)and rated capacity of energy storage units in series-parallel structure,a control method is proposed considering energy storage SOC and rated capacity to achieve a reasonable distribution of voltage between series modules and power between parallel modules.Considering the problem that the equilibrium speed is slow due to the small SOC difference between energy storage units in the later stage of power distribution,a variation coefficient is introduced to dynamically optimize the droop coefficient.Considering that the total capacity of each group is different due to boost or expansion,the capacity weight factor is introduced to make the energy storage unit reach the equilibrium output.The feasibility of the strategy is verified by building a MATLAB/Simulink simulation model.