Optimization Operation Technology Of DC Distribution Center Based On VRB Energy Storage System

Distributed energy storage has the characteristics of low environmental requirements,flexible network access and fast response speed,and has become a current research hotspot in the field of electrical engineering.Among them,the vanadium redox battery(VRB)has received key attention due to its unique advantages and has been widely used in the field of large-scale energy storage technology.In this context,the application of energy storage systems to power systems has also become a research focus.However,existing energy storage systems are often connected to single-circuit 10 k V feeders or low-voltage stations through the Point of Common Coupling(PCC).,The comprehensive benefits of the energy storage system are difficult to reflect.To this end,this paper takes VRB as the research object and proposes a distributed energy storage structure based on flexible interconnection of DC Distribution Center(DDC),which improves energy storage while achieving flexible interconnection between feeders or stations.The benefits of the system.The main research contents of this paper are as follows:First,by comparing the technical characteristics and application occasions of existing energy storage devices,the current research status of flexible interconnected distribution networks at home and abroad and the battery cell balancing technology in the application of energy storage technology are explained.On this basis,a distributed energy storage structure based on the flexible interconnection of DC distribution centers is proposed.Secondly,the working principle of VRB is analyzed,and a simulation model of distributed energy storage is built based on the equivalent loss circuit of VRB.The inconsistency of the battery cells in the VRB energy storage system after grouping is studied,and a DC/DC converter buck-boost equalization circuit with a shared inductor is designed to realize the balance control of the battery cells in the VRB energy storage system.The PSCAD/EMTDC simulation platform is used to build a simulation model of the VRB energy storage system equalization circuit,which verifies the effectiveness of the designed equalization circuit.Finally,study the grid-source load-storage coordination mode based on the DC distribution center.While designing the three working modes of the energy storage system,the static,charging,and discharging modes of the energy storage system,the AC side load balance at both ends of the DC distribution center and VRB storage are considered.The influence of the state of charge(SOC)of the battery in the energy system,the overall control strategy of the DC distribution center based on the VRB energy storage system is proposed,and the coordinated optimization of the grid source charge and storage is realized.A simulation model of a DC power distribution center with two feedback lines connected through a modular multilevel converter(MMC)flexible interconnection was built on the simulation platform.The DC bus side is connected with 3 single cells through a DC transformer.Based on the VRB energy storage system,the simulation results verify the feasibility of the proposed network-source-load-storage coordination mode and the overall control strategy.