直流微电网电池储能系统串并联结构分散控制

电池储能系统BESS(battery energy storage system)串并联结构可以实现小容量低电压等级储能系统接入直流微电网的应用,可以提高端电压且实现储能系统扩容。针对直流微电网BESS的串并联结构,提出一种基于电池荷电状态SOC(state of charge)的分散控制方法。该方法可以实现反下垂控制分配串联模块间电压与下垂控制分配并联模块间功率的目标,且反下垂特性不影响下垂外特性。通过低带宽通信将所有电池SOC信息上传到中央控制单元得到每个BESS的下垂系数与反下垂系数,可以有效实现不同BESS间按容量精确分配功率的目的,消除电池差异延长寿命,避免过放。通过建立小信号模型,分析系统稳定性;通过搭建Simulink仿真模型,验证分散控制的可行性与有效性。

Decentralized Control of Series-parallel BESS in DC Microgrid

The series-parallel structure of a battery energy storage system(BESS) can realize the application of integration of a small-capacity and low-voltage BESS to the DC microgrid, thus increasing the terminal voltage and expanding the energy storage system''s capacity. Aimed at this structure, a decentralized control method based on the SOC of batteries is proposed, which can realize the objective of inverse droop control to distribute voltage between series modules and droop control to distribute power between parallel modules. Moreover, the inverse droop characteristics do not impact the droop characteristics of groups. All the SOC information of batteries are uploaded to the central control unit through low-bandwidth communication to obtain the droop and inverse droop coefficients of each BESS, which can effectively realize the accurate distribution of power between different BESSs according to their own capacities, eliminate the battery difference, prolong the battery life, and avoid over-discharging. By establishing a small-signal model, the system''s stability is analysed. In addition, a simulation model is built using software Simulink, which verifies the feasibility and effectiveness of decentralized control.