Research On Control Technology Of DVR Based On Multiphase Interleaved Parallel Buck Circuit

In the DC energy storage system with high-power impulsive load,the requirements of its energy storage capacity,discharge power and output voltage stability are constantly increasing.The previous energy storage system can not meet the new technical requirements.In this paper,the research work on the related technology of large-capacity DC energy storage system using battery as energy storage component is carried out.The main contents of the research include the core technologies of the circuit topology and control strategy of the dynamic Voltage Restorer(DVR)which can compensate the internal resistance of energy storage components and line impedance.The purpose of this study is to improve the dynamic performance of DVR in order to achieve high stability of output voltage of high-power energy storage system.In this paper,the equivalent circuit model of battery energy storage system is established firstly,and the influence of battery cell parasitic parameters on output voltage under high current output is analyzed.On this basis,the working characteristics of multi-phase interleaved parallel Buck converter,the core part of DVR compensation system,are deeply explored.According to the working principle of the converter,the relationship between the output current ripple of N-phase interleaved parallel Buck converter and the circuit phase number and duty cycle is deduced.Based on this,the main circuit parameters of the converter are designed,and the rationality of the circuit parameters is verified by simulation.Secondly,based on the mathematical model of three-phase interleaved Buck converter,the voltage-current double closed-loop control strategy is applied to the converter to realize the current sharing control between the parallel circuits.Then,the adverse effects of input voltage disturbance on the system are analyzed,and a double closed-loop control strategy with input voltage disturbance suppression is proposed.Based on the traditional double closed-loop control of voltage and current,the control strategy introduces the input voltage information into the current inner loop,which ensures the current sharing among parallel circuits and eliminates the adverse effects caused by the input voltage disturbance,thus improving the anti-disturbance performance of DVR system.According to the theoretical analysis,the validity of the control strategy is verified by comparative simulation.Then,based on the traditional double closed-loop control,the load current feed-forward control strategy is applied to the interleaved parallel Buck converter,which improves the dynamic performance of DVR device.The deficiency of feed-forward control is compensated by the proposed direct power control method based on full response power compensation.The control strategy improves the stability and dynamic performance of DVR by compensating the energy of each part in the dynamic process of the system.The simulation results show that the proposed control strategy has good control performance.Finally,a DVR hardware experimental platform based on 10-phase interleaved parallel Buck converter is built.Based on the theoretical analysis of the previous paper,a comparative experiment is carried out on the proposed control strategy.The experimental results verify the correctness and effectiveness of the theoretical study.