Research Of Grid-connected PV Inverter Output Control Base On Repetitive Control Theory

With the further development of technology and industrialization level, the energy shortage and environment pollution have become the main issues in today's society. Solar energy is widely used, as one kind of inexhaustible, clean and new energy. Especially, photovoltaic grid-connected generation technology is developing very fast.In order to ensure the photovoltaic grid power system operated normally, stably, safely and most efficiently, it is necessary that the control of maximum power point tracking, inverted output and islanding detection are used in this system. According to study on inverted output control technology, the compound control strategy which is based on repetitive control theory is finally adopted in inverted output current control. Then it will become the same frequency and the same phase with network voltage, while less harmonic and high quality. The paper mainly contains 3 aspects:1.This paper analyzes three-phase inverter topology structure and L, LC, LCL filter,then determines the main circuit structure of three-phase photovoltaic grid system. Based on the detailed analysis and comparasion of three present-existed current tracking methods, the suitable system method is determined through simulation experiments.2. In order to suppress the effects on grid-connected current quality, repetitive control strategy is adopted. And the internal structure of repetitive controller and the system performance are analyzed in detail.3. This paper uses two compound control methods. One is state feedback pole configuration combined with repetitive control strategy. Another is classical PI control combined with repetitive control strategy. Based on network voltage feed-forward control, these two control methods are simulated respectively by using simpowersystems toolbox. The results show these two methods are accurate and feasible.