Study On Grid-connected Photovoltaic Inverter And Strategies Of Maximum Power Point Tracking

With the global economy and the rapid growth of population, human demand forenergy is increasingly exuberant. After Fukushima Daiichi nuclear power station accident,many countries continue to declare a moratorium on nuclear power project. At the sametime, as represented by the coal, oil, fossil energy draining and pollution seriously.Countries around the world turn their attentions to renewable energy, solar energy to whichthe cleaning, lasting, pollution-free characteristics of concern. Research on grid-connectedphotovoltaic power technology has become an important major topic in the field of powerelectronics at home and abroad.First of all, a research background and status of grid-connected photovoltaic powergeneration technology is introduced. And topology and control strategy of thegrid-connected photovoltaic inverter is analyzed in the mainstream system. Thephotovoltaic inverter system critical technologies such as photovoltaic inverter ofmaximum power point tracking (Maximum Power Point Tracking, MPPT), topology andcontrol strategy of three aspects of the in-depth research and analysis, focusing on thesystem control strategy and MPPT technology. Based on ARM processor， grid-connectedphotovoltaic inverter system prototype whose capacity of up to7kW is developed, andrelated experimental research, the results verify the correctness of the system design. Maincontent of this paper can be listed as follows:(1) The system chooses DC link circuit topology of BOOST+INVERTER levels of achain of transforms. And analysis of parameters design and working principle is narratedfor this topology. System incorporates current inner loop and voltage outer loop of doubleclosed-loop control strategy, the strategy of DC and AC control independent of each other.(2) Study on commonly used Constant Voltage Method (CVT), Perturb and Observemethod (P&O) and Incremental Conductance method (IncCond).And prove a theory toanalyze the relationship between two methods. The paper gives a novel algorithm of MPPT,and gives the implementation scheme based on BOOST converter. This algorithm has fasttracking speed, high stability characteristics.(3) This paper use ARM processor which has Cortex-M3kernel to design the digitalcontrol system. Every function module realization principle is analyzed, and some function modules of the simulation and the experiment. Simulation and experiment results verifythe feasibility of the digital control system and the validity of the theory analysis.