The control algorithm for a photovoltaic inverter to be applied in weak power grid

The paper analyzes the power-grid connection for a large and medium photovoltaic (PV) plant in details, and it creates a mathematic model for PV inverter and a parameter model for power distribution. The paper also does some research on the grid-connected character between large PV generation system and weak grid, and it focuses on output voltage and current harmonic while connected. Depending on the simulation result and real operating data of three-phase PV inverter, which founded on the traditional controlling algorithm, the paper proposes a brand new way. The method bases on the space-vector theory, and it can validly decrease the PV grid-connected output voltage and current harmonic, and improve the reliability. The theoretical analysis and partial operation results have proved the correctness of grid-connected features; also, it will provide the theory and grid-connected instruction for Chinese new energy strategy as well as the world.