Research On Power Control Of Hybrid Energy Storage System Of Battery And Super Capacitor

Compared with the non-renewable nature of non-renewable energy and the degree of environmental pollution,new energy sources such as wind energy and solar energy stand out in the field of energy application.In this paper,wind energy with large reserves and relatively mature technology is the main research object,focusing on how to better suppress the fluctuation of DC bus power caused by wind,load and power grid fluctuations,and achieve smooth control.In order to meet the power control requirements of wind power generation system,the HESS?hybrid energy storage system?is added to the system.On the basis of controlling the voltage stability of DC bus,the power stabilization control strategy of hybrid energy storage system and the overstepping control strategy to avoid the SOC?state of charge?overstepping of each energy storage element are studied.In order to make the operation of battery and supercapacitor more flexible and controllable,the characteristics of battery and supercapacitor are analyzed and the basic model is simplified.Two-way DC/DC converter is used to realize voltage conversion,and the connection mode is parallel.In order to fully combine the advantages of the two,the power stabilization control strategy of hybrid energy storage system based on battery control is adopted.The low-pass filter is used to filter the fluctuating power of DC bus and extract the low-frequency power.As the power reference of battery energy storage module,the remaining high-frequency power and the uncompensated power of slow battery reaction are controlled by supercapacitor.The purpose of power stabilization is achieved by controlling the stability of DC bus voltage.Based on this,the closed-loop parameters are designed.The stability of the power stabilization control is verified by simulation.In order to achieve better power stabilization effect,the effect of energy storage unit exceeding the limit must be considered in application.Aiming at the problem of the state-of-charge of battery(SOC_bat)exceeding the limit,a hysteresis control method is proposed.The system uses hysteresis control method to collect the charging state of SOC_batat in real time to determine the working mode of the battery.When SOC_batat exceeding the limit,the charging and discharging state of the battery can be adjusted by controlling the compensation power of the inverter side to avoid SOC_batat exceeding the limit.In order to further improve the slow speed of proportional compensation power in low wind speed compensation,a method of constant current charging with low wind speed is proposed,which can quickly restore to normal state and avoid SOC_batat exceeding the limit.In addition,in order to solve the problem of overshoot of the state-of-charge of supercapacitor(SOC_sc),a control method of automatic voltage recovery at supercapacitor terminal is proposed,which can keep the SOC_scc in a relatively stable state and avoid overshoot while having little influence on DC bus voltage.The effectiveness of the energy storage unit over-limit control is verified by simulation.On the basis of theoretical research and simulation verification,the experimental platform of hybrid energy storage system is built,the working principle of each control part is analyzed,and the equivalent configuration scheme is designed according to the actual situation.The control methods proposed in this paper are verified by experiments.