Research On The Influence Of Distributed Energy Storage On The User Side On Distribution Network

Energy storage technology is the key to ensure large-scale development of clean energy and economic operation of the grid,and is also an important part of the smart grid.With the advancement of energy storage technology,cost reduction and the evolution of demand side,the widespread application of distributed energy storage in power systems is an inevitable trend in the development of power grids.The 13 th Five-Year Plan for Renewable Energy Development issued by the National Development and Reform Commission will promote the demonstration application of energy storage technology in line with the National Energy Strategy Action Plan,promote the demonstration application of energy storage technology in the field of renewable energy,and realize the energy storage industry in the market.Breakthroughs in scale,application areas and core technologies are listed as the main tasks of renewable energy development during the 13 th Five-Year Plan period.When the distributed energy storage is connected to the distribution network,the direction and size of the distribution network power flow will change,which will affect the network loss,voltage and relay protection devices of the distribution network.Firstly,a simulation model of distributed energy storage is established,and the mechanism of the influence of distributed energy storage on the distributio n network is analyzed.An index for quantifying the degree of network loss of the distribution network is proposed.The distributed energy storage on the user side is divided into two operating states: charging and discharging.The user-side distributed energy storage access location and access power capacity are simulated respectively.The influence of distributed storage energy access on the transformer side of the transformer is analyzed.The law of the influence of distributed energy storage access on the distribution network on the distribution network is summarized.Secondly,for the typical daily load curve,a location and capacity optimization configuration method based on network loss sensitivity variance of distributed energy storage is proposed.The method considers the charging and discharging operation state of distributed energy storage,and determines the priority order of each node in the distribution network to access distributed energy storage based on the variance of network loss sensitivit y.Taking the distribution network loss and node voltage fluctuation as the objective function,the improved particle swarm optimization algorithm is used to optimize the charge and discharge power of distributed energy storage,and the optimal configuration capacity of distributed energy storage is determined.The simulation results show that the method can determine the position and capacity of distributed energy storage in the distribution network to maximize power local balance,reduce distribution network loss,reduce distribution network voltage fluctuations,realize distributed energy storage,realize the optimal configuration of distributed energy storage in the distribution network.Finally,using the distribution network with distributed energy storage as a model,the author discusses the relay protection of the original distribution network when the distributed energy storage on the user side accesses different sections of different feeders of the distribution network in detail.When the fault occurs in the upstream and downstream of the distributed energy storage and in different locations of the adjacent feeders after the distributed energy storage access to the distribution network,the effect of distributed energy storage on the user side on the three-stage current protection,inverse current protection,automatic reclosing and fuse protection are analyzed.In order to reduce the impact of distributed energy storage on existing protection devices,improvement measures are proposed for existing relay protection devices.