Photovoltaic grid-connected system and control method therefor

Abstract

A photovoltaic grid-connected system and a control method therefor. The photovoltaic inverter is connected to the grid through a synchronous motor back-to-back drive system including two synchronous motors. The photovoltaic inverter is controlled to operate in the current source mode after the photovoltaic grid-connected system is started, the synchronous motor back-to-back drive system is controlled to operate in the generator mode, and the excitation current of the first synchronous motor is controlled to maintain the voltage stability of the AC side of the photovoltaic inverter. Therefore, the stability and safety of the power grid is significantly improved and the impact of intermittent new energy on the power grid is reduced by virtue of the characteristics of the synchronous motor, and the maximum power point of the photovoltaic array can be tracked to avoid loss of power generation, and traditional photovoltaic inverters can be used without any modification.