电压暂降对光伏逆变器的影响分析

Analysis of PV Inverter Characteristics Under Voltage Sags

首先,分析了单相和三相光伏并网逆变器在电压暂降发生时刻的开关模态,对其电流变化规律进行了数学推导;再在理论分析的基础上,对逆变器在不同输出功率、跌落深度和跌落相位角等工况条件下进行了电压暂降实验。实验结果表明,电网电压暂降时由于并网电感两端电压的突变导致电感电流的骤升,电感电流的变化速率远超过逆变器的控制带宽。对于未设计低电压穿越功能的逆变器,电压暂降通常会触发逆变器保护动作封锁驱动导致停机。

Single phase and three phases PV grid-connected inverter operation mode under voltage sags are analyzed in this paper, the current change function is derived. Then, based on the theoretical analysis, experiments are done under different PV output power, voltage drop depth and voltage drop phase angel. The experimental results indicates that inverter grid side current inrushes when voltage sags happened, and the inductor current increase rate is greater than inverter control band. For inverters without low voltage ride through function , voltage sags always trigger inverter protection action.