Research On Optimal Economic Configuration Of Distributed Energy Storage Systems For Improving The Voltage Quality In Distribution Network

With the improvement of power quality requirements of users,the problem about voltage quality in distribution network has attracted much attention.Simply relying on investment to expand power distribution equipment or to upgrade transmission lines,the utilization rate of equipment is low.This paper proposes using advantages of energy storage system(ESS),which can release electrical energy during the peak load period and absorb energy during the low load,to improve power supplying capacity of distribution network and achieve the purpose of improving voltage quality.The location and capacity and its operation scheduling strategy have a direct impact on the overall operating economy of the system and have a greater impact on the voltage quality of the distribution network.For this reason,this paper focuses on the optimal economic configuration of the energy storage system to improve the voltage quality of the distribution network.The development of energy storage technologies,the corresponding economic optimization configuration,and the research of improving voltage quality are introduced.To improve the voltage quality in distribution network,an optimal configuration method for energy storage system(ESS)is proposed,which combines the operation scheduling strategy.Firstly,taking simple line model as an example,the influence of energy storage system on voltage distribution and network loss is analyzed.It is preliminarily concluded that the location and capacity of energy storage system have great influence on distribution network.Next,based on the steady voltage model with ESS and power flow calculation of distribution network,a multi-objective integer programming upper optimization model,which minimizes the investment of ESS,line loss,main network electricity purchasing cost and node voltage safety,is modeled to locate and size the distributed ESS.The objective function contains ESS investment cost,line loss cost and net purchase cost and so on.Then,based on the characteristics of analytic hierarchy process(AHP),it is employed to transform this multi-objective optimization into a single-objective one and the transformed single-objective optimization model is solved by GAMS/BONMIN.Furthermore,an ESS operation strategy lower model taking into account of smoothing the daily load fluctuation is developed and solved to reduce the line loss,main network electricity purchasing cost.Finally,IEEE-33 test system and practical industrial feeder with 700 meters are used to evaluate the performance of the proposed method.The results demonstrate that the reactive power compensation device is not as effective as the energy storage system in improving the voltage at peak load period,because the energy storage device can provide active support for the system at this time.And the proposed bi-level programming model,which concerned ESS operation strategy,can improve network economy,voltage quality and reduce the active power loss effectively without changing the distribution structure.