Research On Super Capacitor Energy Storage In The Application Of Photovoltaic Power Generation System

In recent years with the large scale application of renewable energy power generation such as wind power and solar energy etc,the demand of the power system for energy storage technology is more and more intense.The energy storage technology in the development of electric power is no longer just the icing on the cake,and gradually becomes a must.As a new type of energy storage device,the super capacitor have lots of excellent properties such as high power density,long life and rapid charging,ect.So the experts have payed more and more attention to the super capacitor in electrical engineering domain.But the super capacitor is still in the trail and researching period at present,which results that it cannot be widely used in power system because of its design problem of voltage balancing device and charge-discharge device.At first,in order to solve the voltage-balance problem of super capacitor,a simple but practical voltage-balance circuit was be designed on the basis of summarizing the existing super capacitor voltage-balance method.The simulation model of voltage-balance circuit was established by using Saber software.The simulation results demonstrate that method achieves the reliability for the voltage-balance function.So a new way for this voltage-balance circuit of the super capacitor is provided.After analyzing the topology and characteristics of dc converter,a kind of typical bidirectional DC/DC converter was selected as the super capacitor charge and discharge circuit in the photovoltaic energy storage system.State-space averaging method was used to establish the small signal linear model of the super capacitor energy storage system.According to the double closed-loop constant voltage and limited current control strategy,the simulation model was designed and established by using Matlab/Simulink software.At last,it's demonstrated that the double closed-loop control strategy for the converter can control effectively both voltage and current in the charge and discharge circuit of super capacitor.This kind of control strategy lays a certain foundation for the research of the solar energy storage device based on super capacitor in the next step.In the end,the simulation model of the super capacitor energy storage in photovoltaic power generation system was built by using Matlab/Simulink software.The simulation results show that the super capacitor model is charged by the dc bus of the photovoltaic power generation system under the strong light,and the dc bus is discharged through the super capacitor model under the weak light,which ensure the reliability of the photovoltaic power generation system.