Research of three-loop control method Of PV grid-connected inverter

The traditional control method for PV grid-connected inverter is two closed loop, if this control method is used for PV grid-connected system, the indication of slow response or increased troubles of system design which is caused by instability of switching frequency. This paper presents a three-loop control to overcome such problems, voltage external loop, current middle loop and frequency inner loop are included, this method can solve above-mentioned disadvantages and make the output current THD of grid-connected inverter is a little value. Through building a mathematic model for the PV grid-connected system, the MATLAB/SIMULINK simulation results show that the presented control method is feasible and effective.