弱电网条件下单相光伏并网逆变器的控制研究

单相全桥逆变器单极性正弦脉宽调制(SPWM)相对于双极性调制损耗低,电磁干扰少,更适用于逆变控制,但该调制方式存在一个过零点振荡。在弱电网条件下,由于电网波形畸变,对电网电压的过零点处理尤为关键。针对过零点问题,在并网条件下,采用基于二阶广义积分器(SOGI)的单相锁相环检测电网电压过零点,与传统的过零鉴相相比,具有良好的效果,并在一台4 kW的单相光伏并网逆变器上得到了验证。

Study of Controlling a Single-phase Photovoltaic Grid-connected Inverter Operating in a Weak Grid

The monopole SPWM inverter has merits of lower loss,lower EMI comparing with bipolar SPWM inverter. It’s fit the needs of SPWM control than others methods.But the monopole SPWM still has its disadvantage,the zero point oscillation.In a weak grid,due to the grid aberrance,it’s key of dealing with the zero point.This paper aiming at the zero point,operating in a connected grid,adopting a single phase-locked-loop based on second order generalized integrator(SOGI) test the zero point is introduced,comparing with conventional capture,it has a well effect.The mothed is demonstrated with experiment in a 4 kW single-phase photovoltaic grid-connected inverter.