.10 Kw Photovoltaic Grid-connected Inverter Developed

With the develoment of world economy and increasing demand for energy, energy shortage has become an inevitable problem on the way of social development. Grid-connected photovoltaic(PV) power generation is one of the important strategies to solve energy shortage.In this paper, two stage single-phase and three phase grid-connected PV system are the research objects. The model and characteristics of the PV array, MPPT and anti-islanding protection algorithms, current control of grid-connected inverter, development of the theoretical prototype had all been theoreticlly analyzed and applied in research.PV arrays are the basic components of grid-connected PV power generation system. The analysis of the output characteristics of PV arrays is very essential for the research of grid-connected PV power generation system. In this paper, The mathematical model of PV arrays has been built with the analysis of physically equivalent modelof photovoltaic cell. Based on the built mathematical model of PV arrays, a simulation model for PV arrays is built with simulink modules. A simulation circuit is built to verify the output characteristics of the simulation model for PV arrays.The maximum power point tracking (MPPT) is the key technique influencing conversion efficiency. In this paper, some general MPPT control algorithms had been analyzed and been verified through simulation. By analyzing and comparing the simulation results, this paper made a conclusion of weaknesses of respective algorithms, proposed a variable perturb step MPPT control algorithm based on golden section method and showed the simulation results.Current closed-loop control technique determines the grid-connected current quality of grid-connected inverter and current dynamic response when the outside environment is changing. This paper analyzed the operation principle of boost circuit of two-stage single phase grid-connected PV inverter and single phase grid-connected inverter. Some grid-connected current control methodologies were compared in this paper. An improved predictive current control algorithm was adopted and verified through simulation.Current feed-forward double loop control is the traditional control method of three phase gird-connected inverter. This paper deduced the coordinate transformation based on general equal amplitude vector and built mathematical model of three phase gird-connected PV inverter. According to this mathematical model, current feed-forward decoupled PWM control strategy was deduced and verified through simulation.Island phenomenon is a special problem in grid-connected PV system, which has to be avoided in practice. This paper analyzed the principles of anti-islanding protection and formation of non-detection zone. Some general methods of passive and active anti-islanding protection were analyzed and compared in this paper. Finally, a combination of passive and active anti-islanding protection method was adopted and verified through anti-islanding simulation.This paper designed and debuged the sample circuit, made respective calculation for selected type and hardware designation of two sage single-phase and three phase grid PV inverter. The prototypes of single-phase and three phase grid PV inverters were built and been used for testing MPPT, anti-islanding protection and control algorithms of grid-connected inverter. Experimental results showed the designed control algorithm could ensure stable operation of grid-connected PV inverter.