Study Of Management Strategy For Photovoltaic System With Battery Energy Storage

With the aggravation of global environmental problems and the increasing exhaustion of non-renewable sources of energy,green energy,which is represented by solar energy,has become the hot spot of research.In this paper,the photovoltaic system of low-power storage is the focus of study.Different from large-scale photovoltaic power plants,this kind of system has less power and uses less space,which can be easily applied in everyone's home.Based on the reference and analysis of the current foreign research in the PV energy storage system,in this paper,the three-phase grid-connected PV energy system of duel DC bus in low power is set up,which fulfills several functions,including the photovoltaic cell maximum power point tracking(MPPT),the battery charge and discharge control,the inverter power control and the full-bridge LLC converter in high efficiency and high gain,and so on.Centralized energy management strategy for the entire photovoltaic energy storage system,in the paper,is also formulated.This paper summaries and analyzes the application and prospects of photovoltaic power generation system both at home and abroad.It briefly descripes the structure of photovoltaic power generation systems,and analyzes the development and research status of energy storage of photovoltaic power generation systems.On this basis,the paper carried out the following work.Based on the analysis of the existence of the false disturbance observation method phenomenon,this paper proposes a method combines fixed voltage and variable step disturbance observation method based on power prediction.This method can quickly and accurately track the maximum power point,and can prevent miscarriage when outside conditions mutations.Three stage charging policy is used to charge the battery,which is in line with the characteristics of the battery.The output power of the battery can be controlled accurately by using the discharge control strategy.A full bridge converter based on LLC resonant converter is introduced to realize boost isolation.The parameters design of the resonant converter,the frequency conversion control design and the characteristics of its own circuit are used to make the power switch zero-voltage turn on and the rectifier diodes zero-current turn off.After basic phase-locked loop was studied,the three-phase software PLL in application of control was analyzed.The corresponding control model of power control were established.According to the variation of the photovoltaic cell output power and load power,a comprehensive energy control scheme about PV energy storage system was given and a detailed analysis about the operating mode of the system was carried out.Finally,a whole circuit of PV energy storage system was simulated with the help of simulink in the software of Matlab.The simulation results show that the energy management strategy proposed here was effective to rapidly adjust the working modes of power system and to rapidly stabilize the system when the output power of photovoltaic cell and load power were variable.Additionally,the strategy was adaptable to a variety of operating conditions.