Design And Implementation Of Energy Storage Photovoltaic Grid-connected Power Generation System

As a green power generation method,photovoltaic power generation has been paid more and more attention.Due to the influence of environmental factors,the power generated by photovoltaic cells fluctuates and can’t provide stable power output.During the peak period of power generation,electricity will be wasted,and solar energy can’t be used at night.In view of the above problems,this paper designs an energy storage photovoltaic grid connected power generation system.When the light is sufficient,the surplus electric energy can be stored or transmitted to the power grid.At the rainy time or night,the stored electric energy can be released.It can also be stored during the valley period of power consumption and released during the peak power consumption period.Make better use of solar energy.Firstly,the structure of grid connected inverter and the coupling mode of energy storage device are analyzed.The grid connected inverter adopts two-stage non isolated structure,the front stage is boost circuit,and the back stage is full bridge inverter circuit.The energy storage device adopts DC side coupling mode,which is realized by bidirectional Buck-Boost circuit,and an independent AC-DC charging circuit is added.Secondly,the working principle of every power circuit in system is analyzed.Then,the hardware circuit of the system is designed,mainly including auxiliary power supply circuit,signal acquisition circuit and drive circuit,etc.The signal acquisition circuit is optimized to ensure the sampling accuracy of the control system.Finally,in the aspect of maximum power point tracking（MPPT）algorithm,a variable step interference observation method is designed.The simulation results show that the algorithm can track the maximum power point quickly and stably.In the aspect of grid connected control,voltage and current double closed-loop control is adopted to realize grid connected synchronous control.Also,the feedforward link of grid voltage is introduced to restrain the influence of grid voltage fluctuation on the system.In the aspect of energy management,three working modes of local load priority,battery priority and grid connection priority are designed to make all parts of the system run coordinately and stably.On the basis of the above research,an experimental prototype of 1 KW is built for verification.The experimental results show that each part of the energy storage photovoltaic grid connected power generation system designed in this paper have well performance,which meets the systematic designing requirements.