光储微电网的低电压穿越控制策略研究

针对微电网低电压穿越问题,基于光储微电网系统提出一种光储协调控制的低电压穿越策略。在低电压期间,光伏系统采用最大功率跟踪控制,储能系统采用恒压控制维持直流母线电压恒定,在储能出力已达功率限值仍不能维持直流母线电压在允许范围内时,光伏系统切换为恒压控制。考虑到光储微电网负荷波动性大的特点,设计了一种适用于光储微电网并具有无功补偿功能的限流控制策略,为电网提供电压支撑,同时避免并网逆变器输出过电流。仿真结果表明,控制系统能够充分利用光伏发电能量、维持直流母线电压的恒定、抑制并网电流过电流并能发出无功功率支撑并网点电压,实现了低电压穿越,验证了该LVRT控制策略的有效性。

Low voltage ride-through control of the photovoltaic/battery micro-grid system

For low voltage ride through issue of the micro-grid system, a coordinated control of low voltage ride-through (LVRT) is proposed for the photovoltaic/battery micro-grid system. During low voltage of the system, the photovoltaic system tracks maximum powerpoint of PV panels and the battery system maintains the constant of the DC bus voltage. When power output of the battery system has reached its limit, the photovoltaic system adopts the constant voltage control strategy to ensure a stable voltage. Considering the load fluctuation of micro grid, a current limit control strategy with the function of reactive compensation is proposed. This strategy can provide voltage support for grid side and avoid overcurrent of the converter output. The simulation results show that the solar energy is fully used, the DC bus voltage is maintained at a constant level, the overcurrent of the converter output is avoided and the system voltage is supported by the reactive power from the inverter. The aim of LVRT is realized and the effectiveness of the control strategy is verified.