Research On Control Strategy For Grid-connected Inverter Of Photovoltaic Generation System

Solar energy as clean, a wide distribution range of clean energy with great development potency, has been highly valued by universities and research institutions at home and abroad. The grid-connected inverter is the key component of photovoltaic power generation system, in-depth analysis and Research on its control strategy, which has important theoretical significance and engineering value.Aimed at a kind of two levels type topology of grid-connected photovoltaic inverter, the working mechanism of the pre-stage Boost circuit was analyzed as well as Input-Output relationship was derived. Its mathematical model was built based on State space average method. The working principle of single phase full bridge circuit and LCL filter circuit in a latter stage were introduced. Meanwhile, the features of the active damping method were analyzed.Several common principle of the algorithm of maximum power point tracking was introduced in this paper. Comprehensive analysis of the strengths and weaknesses of traditional algorithms was done. This paper mainly made a research on the non-symmetry fuzzy control algorithm for analysis of working mechanism and its reasoning, while doing the simulation of application of the algorithm in MPPT. The simulation results showed that the algorithm was feasible.In this paper, grid-connected photovoltaic inverter control method was analyzed and compared with the common control algorithms. A single closed loop current tracking control method introduced into the grid voltage feed-forward was designed. The use of the active damping was to suppress LCL filter resonance. Models of the system were built in Matlab/Simulink software environment. Simulation results showed that the method had better tracking results.In the laboratory, hardware of photovoltaic grid-connected system test platform was designed, and control method of grid-connected current proposed was verified. The results showed that the grid connected current obtained by the method had the characteristics of low harmonic content to meet grid requirements.