Research On Grid-connected/Stand-alone Integrated Converter With Photovoltaic And Battery

For relieving the world energy crisis and environmental pollution, human beings must be takemeasures to develop and utilize renewable energy sources. Solar energy, as a new type of greenrenewable energy has been more and more popular as the advantages of clean environmentalprotection, large reserves. Because of photovoltaic greatly influenced by external factor conditionssuch as light and temperature, the power output has stronger intermittent and volatility. So weusually equipped the device of photovoltaic power generation with a certain amount of energystorage.The single phase photovoltaic-storage and grid-connected/off-grid inverter system isresearched in this paper. The key technology of the photovoltaic power generation system, suchas its topological structure, switching condition of each working model and control strategy of theconverters, are approached. And so, the5kW photovoltaic energy storage power generation systembased on DSP.Firstly, base on the demand of application, the topological of a single phasegrid-connected/stand-alone photovoltaic power generation system is designed. The DC/DCconverter on PV side is adopted by a boost converter. The DC/DC on battery side is adopted by abuck-boost converter. And the load side converter is adopted by a single phase full bridge inverter.All these three converters are connected across to the DC bus, and the bus voltage can bestabilized by suitable control.Secondly, the working models of each converter in this system is discussed and their controlstrategy are then presented. Photovoltaic side boost converter can work at maximum power pointtracking (MPPT) mode and constant voltage (CV) mode. It makes photovoltaic component getmaximum output power when working in MPPT mode, otherwise, it can maintain the DC busvoltage stability when working in CV model. Battery side buck-boost converter can work in buckand the boost mode. When working in the buck mode is charged for the battery, and working inboost mode is to control dc bus voltage stability. Single phase full bridge converter can work ingrid-connected mode and off-grid mode. The proposed control strategy can supply stable voltage, current and uninterrupted power for the load.Finally, a5kW prototype of grid-connected/off-grid integrated photovoltaic energy storagepower generation system is developed. Based on the prototype, the experiments on each workingmode and different working models are also operated. The system can operate stable and supplyuninterrupted power for the load.