微电网超级电容器混合储能系统控制策略

Control Strategy of Microgrid Super Capacitor Hybrid Energy Storage System

光伏微电网有离网与并网2种工作模式。在离网模式下由于负荷及可再生能源的功率变化使得直流母线电压产生波动,在并网模式下会因输入功率变动以及非线性负载产生的低次谐波等使并网电流脉动较大,影响电能质量。本文利用超级电容器和蓄电池组2种储能组件构成微电网混合储能方案,使微电网在离网运行时利用超级电容器的快速响应来补偿瞬态功率,从而更快地稳定直流母线电压;并网运行时在传统并网的电压电流双闭环控制策略中,增加超级电容器电流控制环,降低并网时的电流脉动。对混合储能控制方案进行了仿真和验证,结果表明,提出的混合储能控制策略可以使直流微网母线电压的波动控制在5%以内,并且使并网电流总谐波失真维持在7%左右,从而达到控制目的。

Photovoltaic microgrid has two working modes:off-grid modes and grid-connected modes.In off-grid mode,the DC bus voltage fluctuates due to the power changes of load and renewable energy.In grid-connected mode,the grid-connected current fluctuates greatly due to the changes of input power and the low harmonics generated by the nonlinear load,thus affecting the power quality.This paper uses two kinds of energy storage elements of super capacitors and battery packs to form a microgrid hybrid energy storage scheme.When the microgrid runs off-grid,it can make use of the quick response of super capacitor to compensate the transient power,so as to stabilize the DC bus voltage faster.During grid-connected operation,in the traditional grid-connected voltage and current double closed-loop control strategy,the super capacitor current control loop is added to reduce the current ripple during grid-connected operation.The proposed hybrid energy storage control scheme is simulated and verified.The results show that the proposed hybrid energy storage control strategy can control the fluctuation of DC microgrid bus voltage within 5%,and maintain the total harmonic distortion of grid-connected current at 7%,so as to achieve the purpose of control.