Pv Grid Inverter System

Nowadays, as the world energy crisis deepens, all countries in the world is in rapid development of new energy technologies, such as solar energy, wind energy, ocean energy, biological energy and other renewable energy, as a huge amount of renewable energy, solar energy has its merits such as widely region, abundant resources, cleanly with no harm to environment and so on, so it is a main approach to solve the resource crisis. Solar photovoltaic (PV) power generation is the main form of using solar energy, and has broad prospects for development.In this paper, the research object is based on photovoltaic (PV) grid-connected inverter technology, on the basis of the thorough analysis of solar photovoltaic cells principle, it establishes the simple equivalent circuit model of photovoltaic cells based on an external output characteristics, and then through several of the most common maximum power point tracking control method to analyze the working principle and the advantages and disadvantages, it chooses the disturbance observation method as this paper's photovoltaic (PV) grid-connected power system tracking control methods, and the existing disturbance observation method was improved, this paper presents the improved disturbance observation method based on the inverter output current control.Finally, several different existing grid-connected inverter topology is studied, analyzed their advantages and disadvantages of them, taking full account of the inverter service life, cost and efficiency, on the basis of three factors, this paper puts forward a method which is the current type grid-connected inverter topology based on the immittance converter, and analyzes in detail the working principle of the circuit, and deduces characteristics of each part of the current output.On this basis, the topologies of three-phase current type grid-connected inverter is proposed based on the immittance converter and split-phase modulation, the system requires only a immittance converter, the input DC voltage through the immittance converter is transformed into high-frequency sinusoidal Current, and then three-phase AC current source is achieved into the grid through the split-phase modulation of frequency converter. Compared with the traditional current type grid-connected inverter,this system eliminats the DC side of the reactor, reduces the system size and lowers the system costs;and compared with the traditional three-phase current type grid-connected inverter,it just needs a immittance converter, and what's more,it has better system redundancy and stronger capability in dealing with grid fluctuation.Finally, through the Matlab software simulation and the Key Laboratory of Henan Normal University Solar doing field experiments, the feasibility and effectiveness of this system were verified.