Research On Configuration-control Integrated Technology For Distributed Energy Storage Clusters To Connect The Grid Flexibly

At present,the profile of distributed sources in China is extremely uneven,which brings many problems to the configuration and operation of the distribution network.So,it is worth thinking that how to effectively alleviate the imbalanced and inadequate development of distributed sources and promote the renewal of China’s energy structure with new forms.The distributed storage system(DSS)has the characteristics of flexible settings and adjustable power in double directions.It can cooperate with other flexible resources in the distribution network to not only cut peaks and fill valleys,improve power quality,but also make up for the negative impact of distributed renewable sources’ randomness on the safe-economic operation of the distribution network.DSS opens up new ideas and important directions for the future development of distributed sources in China.Considering that the current price of DSS is still relatively high,how to make reasonable allocation and control of DSS to fully exerting its capacity characteristics has become the focus of current research.In addition,with the rapid development of electric vehicles(EV),it is predicted that the large-scale decommissioning stage of power batteries will soon be ushered in.The second use of retired batteries share the cost of EV,enhance the life cycle value of batteries,and save natural resources.So,it is beneficial to both EV and DSS industries.The second-used batteries can be regarded as a kind of DSS and it is cheaper to purchase.How to fully dig and utilize the remaining capacity of the second-used batteries is of great significance.Based on the background above,considering the characteristics of DSS in various forms and flexible layouts,this paper studies the integrated configuration-control strategy of both convergent DSS cluster and autonomous DSS cluster based on the layered architecture.The main contents of this article are as follows:1)Briefly introduce the layered architecture and basic theory that will be used later.Firstly,based on the characteristics of different DSS,this paper studies its application scenarios and designs a layered architecture of the DSS system.Then,this paper introduces the basic theories needed to solve the following models,including a multiagent consensus algorithm based on graph theory,chance-constrained goal programming(CCGP)for handling multiple uncertainties,second-order cone programming(SOCP)for solving optimal power flow of distribution network.2)Aiming at the problem of configuration and control of convergent DSS,based on the "location-capacity" decoupling idea during the configuration phase,the time-series comprehensive sensitivity index is used to select the location of the DSS cluster.Then,considering the multiple uncertainties,a CCGP-based DSS cluster capacity allocation model is proposed.In the control phase,a two-layer control model is proposed based on the idea of“cluster first and then unit” idea.The upper layer relaxes branch flow based on SOCP to optimize the chargingdischarging power of the DSS cluster.Based on the optimization results of the upper layer,the lower layer redistributes the charging-discharging power of the cluster based on the distributed control mode and the multiagent consensus algorithm.Finally,this paper takes the improved IEEE33 node distribution network as an example to analyze and verify the economics and reliability of the configuration-control integrated strategy for converged DSS clusters described in this article.Furthermore,a sensitivity analysis is performed to study the convergence of the consensus algorithm under different communication topologies.3)Aiming at the problem of configuration and control of autonomous DSS,an electric bus charging station(EBCS)is used as an application scenario,and a configuration-control integrated strategy is proposed.In the configuration stage,the number of second-used electric bus batteries(SUEBBs)is optimized to minimize the overall equivalent annual cost(EAC)of EBCS,based on the evaluation model of SUEBBs’ replacement.In the control stage,the coordinated charging-discharging power of the echelon battery system(EBS)and electric bus batteries(EBBs)is optimized in order to minimize the daily electricity cost of EBCS.Finally,this paper takes an actual electric bus charging station as an example to verify the economics and effectiveness of the integration and control strategy for autonomous DSS clusters described in this paper.Furthermore,the impact of the lifespan and price of SUEBBs is analyzed by sensitivity analysis.