光伏并网发电系统的低电压穿越控制策略

为提高光伏并网发电系统的低电压穿越能力,提出一种基于电压定向矢量控制的低电压穿越(Low Voltage Ride-Through,LVRT)控制策略。该策略对光伏逆变器进行电压定向矢量控制,实现有功和无功功率解耦,在电网电压跌落期间,采用直流卸荷电路稳定直流侧电压,根据电压的跌落深度补偿一定的无功功率以支撑电压恢复。通过PSCAD/EMTDC软件对采取LVRT控制策略前后的各电气量进行比较分析,结果表明,采用该策略光伏发电系统可以在电压跌落时保持并网运行,并补偿一定的无功功率以恢复并网点电压,实现低电压穿越。

A control strategy of low voltage ride-through for grid-connected photovoltaic power system

To improve the low voltage ride-through capability of grid-connected photovoltaic (PV) system, A LVRT control strategy based on voltage oriented vector control is proposed. In the strategy, the voltage oriented vector control for the PV inverter is proposed to realize active and reactive power decoupling control. During the grid voltage sags, the unloading circuit are used to make DC voltage stable, and provide reactive power to support voltage recovery according to the depth of grid voltage sags. The PSCAD/EMDC software is used to compare and analyze each electric parameters before and after LVRT control. The results of simulation show the proposed strategy can make PV power system connected to the grid, provide reactive power to support voltage, and realize LVRT.