Research On Modular Power Supply Technology Combining Photovoltaic Power Generation With Energy Storage

With the development of photovoltaic technology,in the structure of large-scale distributed photovoltaic power generation system,energy storage system and photovoltaic power generation system are only connected by buses,two control system are independent of each other and have no information interaction.PV power generation system generally adopts global MPPT control,there is power loss.In the energy storage system,the energy storage devices running in series are lack of series load distribution control.Aiming at the present research situation,this paper designs a modular photovoltaic power supply which combines energy storage and photovoltaic power generation,and can realize multi-module serial-parallel expansion.First of all,the circuit topology of modular PV power supply and its corresponding control strategy are proposed.The modular technology and system integration technology are used to combine PV panel,energy storage device,main circuit and controller into a modular system.Based on this structure,the control strategy applied to the modular system is studied in detail,including the PV power generation technology based on the combination of the maximum power point tracking(MPPT)strategy and the power matching strategy,and the basic discharge control of the energy storage device strategy.In addition to the multi-module system,the corresponding cascade control technology is proposed,which combines the load sharing strategy in series system and current sharing control strategy in parallel system.In order to verify the feasibility of the proposed modular PV power supply design,a modularized PV power supply model with 20 W capacity is designed on the MATLAB / Simulink simulation platform,and the power supply controller is designed.The simulation results verify the feasibility of the MPPT control strategy and the power matching strategy switching.The simulation verifies the feasibility of the load sharing method in multi-module serial operation and the current sharing method in parallel operation.The simulation results are compared with the results of the multi-module direct serial or parallel operation.On the basis of simulation analysis,two 20 W prototypes based on DSP-TMS320F28335 are developed,and the control strategies of each part are verified by experiments.Simulation results and experiment results prove the feasibility of the proposed scheme.The proposed scheme not only meets the distributed maximum power point tracking(DMPPT)requirements of distributed PV power systems when multiple modules are cascaded,but also has the advantages over conventional of the PV power generation control strategy,power matching power generation strategy and MPPT strategy switching can achieve flexible management of PV power.In terms of power output and multi-module energy management,when the residual energy of the total energy storage device in the series system is under the same conditions,this program makes more reasonable use of the residual energy in each module,and realizes the flexible distribution of energy load among the modules.In the parallel system,this program can achieve a multi-module current sharing operation,the load can be average distributed.