| Photovoltaic power generation system is currently an important energy new energy development field,and has attracted extensive attention from many scholars at home and abroad.The whole system is affected by external environmental changes and other factors.The whole system has typical intermittent and volatility characteristics in terms of output power.By increasing and controlling storage devices such as batteries,it is possible to stabilize the randomness and intermittentness of the power supply output of the photovoltaic power generation system.Therefore,energy storage technology also plays an important role in the new energy power generation system.Firstly,this article modeled PV cell and battery.According to the model of PV cell,we analyzed performance curve of the PV cell.And lead to the maximum power point tracking control strategy from analysis result.The efficiency curve of battery is analyzed according to the battery model.From efficiency curve we can designed the parameters of the battery in the experiment.After that,we analyzed the characteristics of the energy storage switching boost converter.It not only allows the upper and lower arm of the inverter to be turned on at the same time,but also reduces the harmonic content of the inverter output,making the system more suitable for grid connection.The structure ensures the continuity of the input current on the DC side,and ensures the utilization efficiency of the photovoltaic cell energy.Moreover,the system has strong boosting capability,so that the system can obtain higher voltage when working at the same duty cycle,no external transformer is needed,and the system is equipped with energy storage links,so that the energy in the system can flow between the photovoltaic cell,the grid-connected inverter and the energy storage battery.Then we divide the system into three parts for control strategy analysis.The first part is the photovoltaic cell part.The maximum power point tracking control strategy is selected for the disturbance observation with the hysteresis comparator.The second part is the energy storage part,which controls the energy of the battery so that the energy flows inside the system and avoids energy loss.The third part is the inverter control part.It chooses to use the phase-locked loop to track the grid phase,and uses the current closed-loop control inverter output current to be in phase with the grid voltage.Finally,we designed the system software and hardware.While considering the constraints of the control strategy,the system security and stability are also considered.From these constraints we given the hardware control block diagram and software operation flow chart of the system.According to the obtained results,the experimental platform hardware construction and software programming were carried out.Through the experimental platform,we carried out the boost experiment,maximum power point tracking experiment,energy storage experiment,grid-connected experiment and normal operation of the system.The theoretical analysis of the previous paper was verified by experiments. |
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