Research On Parallel Operation Of Multi-DC Energy Storage Modules Based On SOC Droop Control

In the context of the country’s vigorous promotion of "carbon peaks and carbon neutrality",it is particularly important to vigorously develop new energy power generation technologies and optimize the energy structure.However,due to the influence of various factors such as nature and geographical environment,new energy power generation technology has certain phenomena such as timing,randomness,and instability,which directly affect the stable operation of the power network.As an indispensable part of the new energy system,the DC energy storage module is of great significance to improve the stability,reliability,speed and synergy of its parallel operation.This article will conduct an in-depth study on the control strategy of multiple DC energy storage modules(two)operating in parallel.Realize the parallel operation of multiple DC energy storage devices with the DC bus to smooth the fluctuations in the power generation of new energy sources such as photovoltaics and stabilize the DC bus voltage.First of all,this article selects a push-pull bidirectional DC/DC converter with high gain characteristics,high efficiency and wide range as the main circuit of this article through the comparison and analysis of different isolated bidirectional DC/DC converters.The working principle of the push-pull DC/DC converter is described,and the working characteristics of the topology in different working modes are analyzed.Furthermore,according to the strong coupling characteristics of the energy storage components contained in the topology,a three-closed-loop control strategy was designed,and simulation verification and analysis were carried out.Then,according to the different differences in the state of charge(SOC)of each DC energy storage module battery,in order to improve the stability of the DC bus voltage operation,this paper conducts an in-depth study on the control strategy of the energy storage module.A hybrid estimation method of SOC is proposed,and on the basis of SOC droop control,the concept of variable speed factor is introduced.On top of maintaining the advantages of plug-and-play and interconnectless communication,it accelerates the convergence speed of the system and keeps the bus voltage stable.SOC quickly tends to equilibrium,and its effectiveness is verified by simulation.Finally,an experimental platform for parallel operation of multiple DC energy storage modules with push-pull bidirectional DC/DC converters as the connected carrier is built,and an improved control strategy is adopted to regulate the forward discharge operation status of the multiple DC energy storage modules.The comparative analysis of experimental results and theoretical simulation verifies the correctness and feasibility of the improved control strategy.