Research And Design Of4KW Charging Station Rooftop Photovoltaic Grid-connected System

With the increasing environmental pollution and energy crisis, the development andutilization of new energy is urgently needed. Among them, the solar energy as the one kindof green, clean, renewable new energy is paid more and more attention by people. Thegrid-connected solar inverter is bounded to be actively developed as an important form ofphotovoltaic use. This paper begins with several typical network topology of the PV inverter.It detailedly analyzed the principle of photovoltaic, the maximum power point trackingalgorithms, network control algorithms and island effect detect protection.First, the paper describes the current status quo of photovoltaic technologydevelopment at home and abroad and gives the significance of the research. Then it explainsthe physical properties and mathematical models of the solar cell. PV modules can beformed by the photovoltaic cells of series and parallel, and thus constitute a photovoltaicarray. After comparative analysis of several classical maximum power point trackingalgorithm, it finally chooses the algorithm which based on the directly control of the current.Second, the paper gives several topology of the grid-connected PV inverter andanalyzes the switching state of the non-isolated grid inverter topology. Through detailedanalysis of the phase lock loop control and inverter control the author decides to use thecontrol strategy based on the photovoltaic cell output power to adjust the grid currentamplitude.Third, by using the software of PSIM the author do the simulation of the grid-connectedPV inverter system. And the actual verification is carried out by the experiment combinedwith the existing laboratory equipment. The output waveform of grid-connected systemmeets the requirement.Finally, based on the previous successful simulation and actual verification thehardware circuit is designed independently. The island effect of the current system is alsoanalyzed and specific types of islanding detection and protection measures are given out.