Improved three-phase LCL photovoltaic grid-connected inverter control method

The invention mainly provides an improved three-phase LCL photovoltaic grid-connected inverter control method, which is characterized in that current and voltage three-closed-loop control is adopted. The method specifically comprises the steps of S1, acquiring grid current signals ia, ib, ic, acquiring synchronous current signals through a phase-locked loop, and then acquiring current signals i , i in a static coordinate system through abc/alpha beta coordinate transformation; S2, sending a difference value between DC bus voltage Udc and a reference value Uref to a proportional resonant (PR) controller, increasing second-order generalized integral Hi(s) on the basis of a transfer function Gpr=Kp+Kis/(s +omega ) so as to acquire a new transfer function Gpr=Kp+ Kp+Kis/(s +omega )+Hi(s); S3, carrying out addition-subtraction operations on current signals i , i outputted by a PR regulator and the current signals i , i respectively so as to acquire current signals, and carrying out alpha beta/abc coordinate transformation on the sum of the current signals and inner ring capacitive current signals of a proportional controller (P) so as to generate a corresponding SVPWM signal control power tube. Simulation and experimental results show that the method provided by the invention effectively improves the grid-connected current waveform of the system, and high-quality grid-connected current is acquired.