Impacts And Countermeasures Of Distributed Energy Storage On Safe Operation Of Distribution Network

As the last link between the power grid and the user,the distribution network is of great significance to the safety and reliability of the user’s electricity consumption.At the same time,with the rapid development of distributed energy storage,it is increasingly connected to the distribution network,mainly used in the distribution network side,power supply side and user side.The access of distributed energy storage to the distribution network can cut peaks and fill valleys,delay the upgrading and transformation of the distribution network,and promote the consumption of new energy,but its access also brings certain challenges to the safe operation of the distribution network.The characteristics of the power supply will cause certain changes in the flow of the distribution network,affecting some applications installed in the traditional distribution network.For example,it will have a certain impact on the traditional relay protection of the distribution network.At the same time,how to reasonably configure distributed energy storage to maximize its performance is also an important research direction for distributed energy storage to be connected to the distribution network.Focusing on the impact of distributed energy storage on the distribution network,this thesis selects three aspects: the impact of steady-state operation,the impact of relay protection and the impact of fault recovery,and analyzes and summarizes its impact mechanism and evaluation methods from a theoretical point of view.And on this basis,formulate corresponding countermeasures.In terms of the optimal configuration of distributed energy storage in the distribution network,this thesis considers the distributed energy storage directly connected to the distribution network and the electric vehicle load considering V2 G,and establishes an optimization model of the distribution network.The two-stage optimization method of the power grid is used to optimize the configuration.This method selects the location of distributed energy storage based on the standard deviation of network loss sensitivity,solves the distribution network model through the second-order cone optimization algorithm,and finally conducts simulation calculations in the IEEE33 distribution network example and actual example model.The optimal configuration scheme of distributed energy storage and V2 G electric vehicles is obtained,and the results show that this scheme can give full play to the advantages of energy storage and improve the economy,safety and stability of the distribution network.In terms of relay protection of distribution network with distributed energy storage,this thesis proposes a wide-area protection scheme of distribution network with distributed energy storage.The scheme first divides the distribution network into regions,and uses the intelligent terminal unit STU to collect pre-fault and post-fault current information of the line.By comparing the fault current information in different regions,the fault region and location are determined.Finally,the simulation is carried out in the actual distribution network model.The simulation results show that the scheme can accurately find the fault area and location,and effectively solve the limitation proposition of the original protection of the distribution network after the distributed energy storage is connected.In terms of fault recovery of distribution network with distributed energy storage,this thesis proposes a fast fault recovery method for distribution network with distributed energy storage based on the basic principle of immune mechanism.Drawing on the efficiency and self-learning ability of the immune mechanism,a fault recovery model is established,and its fault recovery process is given.Finally,simulation analysis is carried out in the improved actual distribution network example.The results show that this method can give correct fault recovery results,and has high efficiency and good selflearning capacity,and improve the reliability of the distribution network system.