大型光伏电站并网暂态特性研究

Analysis of transient characteristics when large-scale photovoltaics are connected to a power system

为了准确研究光伏系统故障暂态特性,根据光伏发电系统具有随机性和间歇性的特点,研究了光伏系统送出线上发生不同故障类型的暂态过程。针对电网电压对称跌落和不对称跌落情况,提出了不同情况下的控制策略,得到了相应的控制目标。基于提出的控制策略和搭建的光伏模型,针对不同故障类型,模拟了光伏电站馈出的功率、电压和电流的暂态过程。仿真结果表明,光伏系统的故障暂态特性主要受控制策略影响,与传统发电机模型有较大区别,对光伏并网以及送出线保护具有重要的现实意义和理论意义。

To accurately study the fault transient characteristics of a photovoltaic system,given the random and intermittent characteristics of a photovoltaic power generation system,the transient process of different faults on the tie-line of a photovoltaic system is analyzed.For power system voltage symmetrical and asymmetrical dropping,different control strategies are proposed under different circumstances.Then the corresponding control targets are obtained.Based on the proposed control strategies and the established photovoltaic models,aiming at different faults,we simulate the transient process of power,voltage and current from the photovoltaic side.The simulation results demonstrate that the transient process is really influenced by the control strategy and quite different from traditional generators.This has important practical and theoretical significance on tie-line protection,as well as the incorporation of photovoltaics in the power grid.