基于改进型电网电压前馈的光伏电站低电压穿越控制策略

摘要

针对三相并网光伏发电系统的低电压穿越问题提出一种基于全电压前馈的改进型电网电压前馈控制策略.在建立三相并网光伏发电系统数学模型的基础上,推导出控制回路中前馈项的具体表达式,将电网电压通过该前馈项反馈到控制环路中,所构成的整体控制方案能明显降低电网电压突变对系统并网电流的影响程度,从而改善低电压穿越期间的过电流和谐波问题.在基于实时数字仿真仪搭建的硬件在环平台上对该策略进行了验证,通过与传统控制方法的对比证明了其在改善并网电流方面的可行性与有效性.%A full voltage feed-forward control strategy is proposed for the LVRT(Low-Voltage Ride-Through) of grid-connected three-phase PV(PhotoVoltaic) power generation system.A mathematical model of PV power generation system is built and the specific expressions of feed-forward terms in the control loops are derived.The overall control scheme,which feeds the grid voltage forward via the feed-forward terms to the control loop,reduces significantly the impact of sudden grid-voltage change on the grid-connecting current to suppress the over-current and harmonics during LVRT.Verification is carried out on the HIL(Hardware-InLoop) platform based on RTDS(Real-Time Digital Simulator) and the feasibility and effectiveness of the proposed control strategy in improving the grid-connecting current during LVRT are proved by the comparison between it and traditional control method.