Simulation Research On Single-phase Photovoltaic Grid-Connected System

Solar energy is an ideal energy in nature, it distributes widely without regional limits andcan be used freely without exhaustion, it is the finally reliable energy of human. Solarphotovoltaic (PV) power generation has many advantages, such as safe and reliable, withoutnoise and pollution, it is widely available and not limited by region, no fuel consumption, nomechanical rotating components, low fault rate, convenient maintenance, can be unattended,short construction cycle, arbitrary size, no necessary transmission lines, and it can becombined with architecture conveniently, these advantages are much greater than those ofconventional power generation and the other power generations.In the photovoltaic power generation system, the optimization design of the system isvery important, it is a guarantee of reducing the the cost of the system, improving thereliability and efficient of the system. As the PV system control strategy in progress, in thiscase, to shorten the design and development cycle of the PV power generation system andsave costs, paying attention to related computer simulation and aided design technology, thefirst one the choosing the simulation platform software, it is the basis to realize the simulationand aided design. In this paper the PSIM software is chosen as simulation software of theoverall PV power system.Make a analysis of PV cells’ physical characteristics, establishing a mathematical modeland a simulation model in PSIM software which could reflect the light intensity andenvironmental temperature, the result of simulation could prove its reliability. The maincircuit of the PV power system chooses the two levels without transformer. In order to use thesolar energy effectively, the maximum power point tracking (MPPT) is the most importantpart, in this paper, based on the simulation research on original algorithm of perturbation andobservation (P&O) method and conductance increment method (IncCond), designing a newalgorithm which can be called three-points with variable steps perturbation observationmethod, take a simulation in PSIM, realizing the MPPT control via controlling the duty cycleof IGBT in the boost circuit, and the simulation result shows that the new algorithm is betterthan the old one. On the control strategy of grid-connected inverter, using the currenthysteresis control method based on the phase lock loop (PLL), the simulation result showsthat the grid-connected current has the same frequency and phase with the grid voltage, andthe power factor is1.