光储微电网锌溴电池储能系统功率优化控制

Power optimization control strategies of zinc bromine flow battery energy storage system in photovoltaic/battery micro-grid

随着分布式风电、光伏等可再生能源的不断发展,可再生能源本身具有间歇性、随机性特征,给电网安全稳定运行带来很大挑战。针对平抑光储微电网中光伏发电功率波动的需求,提出一种采用锌溴液流电池储能的功率优化控制策略。首先,基于锌溴液流电池的工作原理,建立了其等效电路模型;然后,采用储能变流器级联多重双向直流变换器电路拓扑,分别建立了以稳定直流母线电压为目的的储能变流器矢量控制策略和以电池荷电状态为约束的锌溴电池充放电切换的DC/DC变换器双闭环控制策略;以电池荷电状态和直流母线电压为约束条件,提出一种新型的锌溴电池储能系统功率优化控制策略,同时提出了一种减小充放电切换时直流母线电压突变的混合储能方法;最后,搭建了25 k W/50 k Wh锌溴液流电池储能系统试验平台,在微网并网模式下开展了锌溴储能系统充放电特性研究,结果表明,所提功率优化控制策略能够有效地平抑光伏发电功率波动,所提混合储能方法很好地解决了直流母线电压突变问题。

With the continuous development of distributed wind power, solar and other renewable energy sources, renewable energy sources which have its own features, such as intermittent volatility, bring great challenges to the safe and stable operation of power grid. Aiming at meeting the requirement of balancing the fluctuating photovoltaic generation of photovoltaic/battery micro grid, the optimization power control strategies of the zinc bromine （Zn-Br） flow battery storage were proposed. Firstly, the equivalent electrical circuit model based on the working principle of the Zn-Br flow battery was established; secondly, a vector control strategy of energy storage converter was presented to keep the stable DC bus voltage, and a double closed loop control strategy of DC/DC converter was established to switch charge-discharge style as a constraint of the SOC for the Zn-Br flow battery by using energy storage converter cascade multiple bi-directional DC/DC converter circuit topology. The optimization power control strategies of Zn-Br battery energy storage system as a constraint of state of charge（SOC） on the Zn-Br flow battery were proposed, and a hybrid energy storage method was proposed to solve the problem of the DC bus voltage mutation when the charging and discharging switch. A 25 kW/50 kWh Zn-Br flow battery energy storage system test platform was built, and the charging and discharging characteristics of Zn-Br energy storage system were researched in microgird grid-connected mode. The test results show that the proposed power optimization control strategies for Zn-Br energy storage system can smooth photovoltaic generation power fluctuation, and that the proposed hybrid energy storage method is a good solution to the problem of the DC bus voltage mutation.