The Research Of Photovoltaic Power Generation System With Battery Energy Storage

In recent years,photovoltaic power generation has become an important form of distributed generation.However,photovoltaic power generation is strongly influenced by environmental factors such as light intensity and temperature,the output power has strong intermittent and volatility,which brought negative impacts on large-scale application.Photovoltaic power generation with energy storage has strong controllability and initiative,and this system can not only percolate through the grid better,but also realize demand side management effectively,to meet the diverse demand for electricity.The combining utilization of photovoltaic and energy storage is an important subject in the field of photovoltaic research.The PV system with battery energy storage is selected as main object and the main theses of this research are as follows:Firstly,this paper studied the configuration method of energy storage to suppress the PV power fluctuation.The volatility is quantitatively analyses in time domain and frequency domain,and the configure principle of capacity and power is discussed,then the configuration methods based on low-pass filter and moving average arithmetic are given.These two methods are tested and contrasted by actual examples.The special requirements of energy storage system for power stabilization are summarized,the technical performance and economic performance of the three typical energy storage devices are compared,and the factors affecting the cost of energy storage is discussed.The research results can provide reference for energy storage configuration of PV farms.Then,this paper discussed the topology structure of the system,and introduced the operating principles and mathematical models of photovoltaic interface converter,energy storage interface converter and ac interface converter in turns.The operation modes of each interface converter are analyzed and summarized;corresponding control strategy for each operating mode is designed.The control strategies are verified both by simulation and experimental platform,laying the foundation for the study of the subsequent chapter.Next,this paper studied operation control method of overall system.From the point of view of energy flow,three operation modes of the system are concluded;they are power generating in grid-connected mode,battery charging in grid-connected mode and island operation mode.Afterwards,from the point of view of maintaining system stability and improving energy efficiency,the energy use priorities and the targets of operating control are set.Power output control of photovoltaic power generation unit,droop and anti-droop control of energy storage unit are designed based on the mechanism of dc bus signaling,and operating control technology scheme of each operation modes are given.Simulation results show that the method can control the energy flow reasonably and achieve efficient operation of the system independently.Finally,this paper introduced the experimental platform.The hardware architecture and parameters have been discussed;the schematic diagrams of the main circuits are given.In addition,the human computer interaction system is designed.After designing the sampling control program and PLL program,the physical prototype and equipments used in the process are given.