大型光伏电站变结构低电压穿越控制策略研究

Research on Low Voltage Ride Through of Large-Photovoltaic Power Plants

通过分析大型光伏电站在电网故障下的特征,研究了大型光伏电站低电压穿越的变结构控制策略。在电网发生故障时,通过变结构控制策略,限制逆变器交流侧电流幅值,同时切换网侧电压外环控制,通过比例调节器,将电压跌落深度转换为无功电流缺额,向电网发送无功功率,提高电网电压的恢复能力,并将此控制策略应用于多台并网逆变器联合运行。仿真结果表明,所提出的变结构控制策略能够有效限制交流侧电流幅值,使逆变器不脱网运行,提高了故障点电压的恢复能力,实现光伏电站低电压穿越的要求。

Based on an analysis of the performance of largephotovoltaic power plants in the symmetrical grid fault,this paper studies the control strategies to improve the ability of low voltage ride through. When a symmetrical failure occurs to the power grid,the structure-change control strategy as proposed in the paper helps to limit the current amplitude of the converter at the AC side,at the same time,to switch over the outer loop voltage control at the grid side and convert the voltage dip depth into the reactive current shortfall through the proportional regulator to send reactive power into the power grid to streng-then the recovery of the grid voltage. And this control strategy can be applied to multiple inverters in parallel. Simulation results show that this control strategy can effectively limit the current amplitude at the AC side,support fault point voltage recovery and meet the requirements of the State Grid Corporation for the low voltage through of photovoltaic power plants.