Grid-connected PV Device

With the development of economy, the consumption of energy resources is growing, the ecological environment is damaged, and the new energies with non-polluting and long-term supply are seeked by the whole world. Solar energy as the inexhaustible and pollution-free renewable energy is widely accepted. The solar energy utilization is taken into account by more and more countries, the development trend of which is the grid-connected PV(Photovoltaic).Firstly, the basic working principle and the influence factors of the PV cells are studied. Several commonly-used MPPT (Maximum Power Point Tracking) control methods are analyzed, and their merits and demrits are compared. On this basis, the scheme is determined and the corresponding flowchart is given.Secondly, the three-phase grid-connected PV system including system topology, control strategy is analyzed theoretically. The single-phase simulative grid-connected PV system is studied, and its hardware circuit and software programs are designed based on DSP chip TMS320F2812. The hardware circuit is composed of main circuit and control circuit. Each circuit module is analyzed in detail, and the design parameters are calculated. The compositions of the software part include AD sampling, frequency and phase adjustment, SPWM waveform generation and MPPT algorithm realization. The PI algorithm is added in the incremental-conductance algorithm to realize MPPT control and optimize the system response.Finally, Experimental results of single-phase simulation grid-connected PV system validate the reasonableness of the design.