Research On Lead-acid Battery Backup And Online Repair System

With the rise of the concept of distribution network automation,lead-acid battery backup system applied in distribution terminal equipment has been widely used.However,the capacity decline and premature failure of lead-acid battery due to vulcanization not only make the maintenance cost of traditional battery backup system greatly increased,but also reduce the reliability of the whole distribution network automation system.In the traditional battery backup system,two unidirectional DC-DC converters are used to realize the charging and discharging function of batteries,which also makes the system more complex and costly.To solve these problems,this paper designs a lead-acid battery backup and online activation repair system based on distribution terminal equipment.The main work of this paper is as follows:(1)In order to solve the vulcanization problem of lead-acid batteries in traditional backup systems,an activation repair circuit is added.Firstly,according to the structure of lead-acid batteries and the principle of electrochemical reaction,the main reasons for the capacity decline and failure of lead-acid batteries are analyzed.Then,aiming at the vulcanization problem of batteries,the working principles of pulse repair method and high frequency resonance repair method are respectively carried out.The feasibility of the two repair methods is verified by experiments.The comparison experiment shows that the pulse repair method has better repair effect than the high frequency resonance repair method.(2)In view of the shortcomings of high cost and low reliability of battery charging and discharging circuit in traditional backup system,bi-directional DC-DC converter is used instead of traditional unidirectional DC-DC converter to realize battery charging and discharging function.The working principle of traditional Single-phase Shift Dual Active Bridge(SPS-DAB)is studied.Aiming at the shortcomings of power return and high current switching off of SPS-DAB,a control method of Triangular Current Mode Dual Active Bridge(TCM-DAB)is proposed.The working principle and soft switching state of TCMDAB are deeply studied.The corresponding formula and parameter optimization method are deduced.Finally,the feasibility and correctness of the theory are verified by simulation.(3)In order to realize the power supply function of the system,a high reliability dual switch forward converter is selected to design the power supply system.The input circuit,magnetic components and peak current mode control of the power supply are studied in depth.The formulas for calculating the parameters of each component and the method for selecting the components in the power supply are given.Finally,an experimental prototype is made,and the experimental data show that the prototype can basically meet the design specifications.