Research On Three-phase Photovoltaic Grid-connected Inverter Based On The Software Phase-locked

Because of solar energy’s efficient, non-polluting, and a wide range of resources, making it the representative of new green energy. Therefore, the development and utilization of solar energy take a universal concern, especially the use of mothed is respected. The inverter and its control technology, as the core of the solar power system, which are been focused on by various countries, especially with regard to the development and application of grid PV inverter.After analyze to a photovoltaic inverter and its control system, this paper chooses two-stage topologies:the top-level DC Boost conversion and post-DC/AC inverter. using the improved maximum power point tracking controlalgorithms and new grid inverter control strategy respectively,and tracking it in the actual PV grid inverter.Firstly, after analyze to the principles and characteristics of photovoltaic cells, establishing a simple and effective mathematical model and MATLAB simulation model. The maximum power point tracking control algorithm adopts incremental conductance of variable step size method, to achieve accurate and fast tracking of the maximum power point under different temperature and different light intensity conditions, and test it through MATLAB simulation. Secondly, the design of a two-stage three-phase photovoltaic grid-connected inverter topology: top-level is the DC boost conversion and post-DC/AC grid inverter, and establish the mathematical model of grid inverter, and it uses double-loop control, which are decoupled current inner loop and outer voltage loop, select the software phase-locked loop to get the grid angle, achieve independent control of reactive current and active current decoupling and inverter output grid current and grid voltage same frequency and phase. The analysis of standards about grid voltage drop and low voltage through, using the dynamic reactive current of low voltage ride through as suppuration.The grid inverter hardware and software design bases on the controller which uses TMS320F2812as the main control chip. Finally, the simulation and experimental validation of control strategy by MATLAB simulation and15kW prototype. Simulation and experimental results show that the inverter can realize interconnection unit power factor and low voltage across functions.The simulation and experimental results show that the design can achieve the desired goals basically.