Research Andimplementation Ofcontrol System In Three-Phase Grid-Connected Pv System Based On DSP

Accompanied with the increasingly prominent of energy crisis and the aggravation of pollution of the fossil, the sustainable and abundant solar energy has beendrawn much attention gradually.One of the way to take advantage of solaris grid-connected generation, and its critical technologies have been the important direction of research around the world. The single-state grid-connected PV inverter with characteristics of simple circuit topology and high efficiencyhas beenapplied widely to grid-connected PV system.The three-phase single-state isolated grid-connected PV system has been researched on and analyzed by the mathematic model which was modeled based on the circuittopology.The dual-closed loop control system in d-q axis was established with feed-forward decoupling method.Pulse width modulation (PWM) and phase-locked loop (PLL) which are the critical technologies of grid-connectedtechniquehave been introduced in this paper, the characteristics of SVPWM with seven-segment scheme and the procedure of digital implementation have been described. SVPWM and SPWM were compared by simulation in MATLAB, and the advantages of SVPWMwereverified inthe result. The control system of SPLL is designed based on the analysis of mathematical model of the three-phase PLL, and then, the system performance is verified by examining the stability and computing steady state error.The grid-connected system and grid-connected PV system with the feed-forward decoupling strategy and dual-closed loop scheme is designed and modeled in MATLAB.The results not only show the system’s ability of controlling active and reactive power separately, but also tracking maximum power point of PV in different environment conditions.Based on the analysis and simulation, an experimental platform of grid-connected PV system is builded up with the leading control chip, DSP (TMS320F2812).The test results indicate that the critical algorithm is valid and the system is capable of capturing the instantaneous phase, modulating the pulse width timely, and transporting the sinusoidal output current and high power factor electric energy.