Research On FM Technology Of Photovoltaic System Based On Energy Storage

In recent years,China's new energy has shown a state of spurt development,especially the development of photovoltaic power generation and wind power generation,especially the rapid development of photovoltaic power generation in recent years.However,the increasing number of new energy grids has also brought some challenges to the grid.For example,both wind power generation and photovoltaic power generation have great volatility,which will lead to an increase in energy imbalance in the short-term grid,which brings challenges to the grid's ability to maintain frequency stability.The energy storage has good frequency modulation performance,and the response time is relatively fast It has a good effect in the application of energy storage in the frequency modulation field.Therefore,this paper mainly studies the frequency modulation application of energy storage in photovoltaic systems,and comprehensively uses centralized energy storage systems for large-scale photovoltaic power plants,distributed energy storage systems and distributed photovoltaic power generation systems,analysis.Firstly,the mathematical model of photovoltaic power generation system based on energy storage is established.Topology is presented based on the energy storage of photovoltaic power generation system,and on this basis,several important unit of the photovoltaic system control strategy,and establish the corresponding mathematical model,mainly contains the MPPT photovoltaic power generation system,DC/DC boost chopper circuit and inverter side this three parts model of photovoltaic power generation system in which the incremental conductance method as an example to achieve maximum power point tracking of photovoltaic system,and through the voltage loop and current inner loop control strategy to realize the active reactive power control,The DC/AC converter on the network side can control the measured active power and reactive power through the control strategies of voltage outer loop and current inner loop.At the end of the chapter,the mathematical model of photovoltaic power generation system was built by Matlab/Simulink simulation software,and the effectiveness of control strategy of each unit of photovoltaic power generation system was simulated and verified.Secondly,on the basis of the first chapter,the research on frequency modulation of centralized energy storage system in large photovoltaic power station is carried out.A large grid-connected photovoltaic power generation system based on centralized energy storage is proposed.In this topology,the energy storage system is in parallel with the photovoltaic system,and the two are connected to the AC power grid tlirough their respective DC/AC inverters.Meanwhile,the mathematical model of centralized energy storage system is established,and the droop control strategy of DC/AC inverter is emphatically studied,and the charging and discharging control mode of battery is designed.Finally,Matlab/Simulink simulation software was used to build relevant mathematical models to verify the primary frequency modulation characteristics of the centralized energy storage system.Finally,aiming at engineering problems such as inverter tripping caused by large fluctuation of ac side voltage in the case of sudden change of illumination intensity of distributed photovoltaic power generation system,research on frequency modulation of distributed energy storage photovoltaic power generation system is carried out.The droop control strategy of DC/DC bidirectional chopper circuit of energy storage unit is proposed,in which frequency is used as outer loop control signal and current as inner loop control signal.The simulation model of photovoltaic power generation system based on distributed energy storage was built based on Matlab/Simulink simulation software,and the simulation research was conducted based on two operating conditions,namely light intensity mutation and power grid frequency drop,to analyze the characteristics of frequency modulation and stable ac side voltage of the system.At the end of the chapter,the experimental verification of distributed energy storage primary frequency modulation characteristics under two working conditions of power grid frequency drop and surge is carried out.