| With the rise of large-scale new energy power generation,China’s photovoltaic power generation has increased significantly,but the volatility and uncertainty of photovoltaic power generation have brought severe challenges to photovoltaic grid connection.At present,the most widely used is to rely on energy storage devices to flatten the output power of photovoltaic electric fields,in addition,according to the grid-connected fluctuations and flattening effects,different power decomposition methods have different treatment effects on photovoltaic electric fields.Based on the current research status at home and abroad,this paper adopts a hybrid energy storage array system composed of a 1 MW/250 kWh flywheel energy storage unit and a 250kW/150 kWh lithium-ion battery energy storage unit model,and processes the output power of the photovoltaic electric field by integrating three power decomposition methods empirical mode decomposition,wavelet packet decomposition and improved wavelet packet decomposition and establishes an economic model of photovoltaic farm-hybrid energy storage system,and uses the historical output data of the typical day of the photovoltaic electric field.This paper compares the flattening effect and economic benefits of different decomposition methods to treat photovoltaic farms.The main work is as follows:(1)In this paper,the connection mode between different energy storage types and the structure of hybrid energy storage system connected to the photovoltaic electric field are analyzed,and the models of 1 MW/250 kWh flywheel energy storage unit and 250 kW/150 kWh lithium-ion battery energy storage unit are established.Then,a simulation model is established based on Matlab/Simulink for feature verification,and finally the dynamic response characteristics of flywheel energy storage unit and lithium-ion battery energy storage unit are analyzed and compared.(2)Set Ensemble mode analysis,wavelet packet decomposition and improved wavelet packet decomposition are used to carry out power suppression treatment of photovoltaic electric field.Firstly,the principles of the three decomposition methods are introduced,and then the parameters of the decomposition methods are determined according to the grid-connected standards of photovoltaic electric field output power,so as to obtain the charging and discharging instructions of the hybrid energy storage system.Based on the response characteristics of different types of energy storage arrays,the node k values of the low and high frequency decomposition of charging and discharging of the hybrid system processed by different decomposition methods are determined,and the configured capacity of each energy storage unit is calculated.Finally,on the premise of meeting the requirements of hybrid energy storage capacity configuration,the capacity configuration of hybrid energy storage system is obtained,and the typical daily data of photovoltaic electric field is verified by example,and the grid-connection situation after processing by different methods is compared.(3)The energy management control strategy of the energy storage system is designed,and the working area of each type of energy storage unit is first divided.With the goal of reducing the number of charging and discharging switches of energy storage arrays and improving the stability of energy storage systems,a coordinated control strategy of energy storage arrays is established,and the proportional power allocation method is used to distribute energy to energy storage devices in different states.At the same time,the economic model of photovoltaic farm-hybrid energy storage system is established,and the income of photovoltaic farm under different methods is calculated by introducing three parts:joint system income,investment cost and operating cost.Through the typical daily data of photovoltaic farms,the economic calculation is carried out,and the annual profit and expenditure of photovoltaic farms under different methods are compared and studied. |
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