Distributed/Centralized Energy Storage Palacement And Capacity Selection Considering Distribution Network Power Losses And Voltage Swings

Increased grid integration of photovoltaic(PV)has aggravated the uncertainty of distribution network operation.As an important part of microgrid,energy storage system(ESS)can not only improve economic benefits,but also has important significance for maintaining frequency stability of distribution network and ensuring power quality.The change of grid integration location of PV/ESS will affect the distribution network loss and power quality.The fault characteristics of distribution network with PV/ESS integrated are different from those of traditional power grid.For an active distribution network(ADN)with PV,optimal configuration of distribution network is investigated with the following three contributions:1)The mathematical model of distribution network with PV and ESS is established,and the control strategy of PV and storage are deduced.Based on this,the restraining effect of ESS on the fluctuation of active power of PV is analyzed.The calculation method of ESS compensation power and frequency fluctuation suppression of distribution network based on automatic generation control(AGC)strategy are proposed is proposed.A 10 k V distribution network model with PV / storage is established in the time domain simulation environment PSCAD/EMTDC.The results show that the proposed control method can optimize the effect of ESS frequency fluctuation suppression.2)For a distribution network with PV,the impact of the PV location on the network power losses and voltage swing is investigated with analytical derivations reflected by the line impedance.Optimization approaches of the PV/storage location with consideration of two aspects,i.e.minimum network power losses,minimum voltage swing,are proposed.A PSO algorithm is used to synthesize an optimal compromised solution so as to determine the location of PV/ESS.A 10 k V distribution network with PV/ESS is established on the timedomain simulation environment PSCAD/EMTDC.The simulation results justify the theoretical analysis and indicate that when the active power of the PV/ESS is more/less than twice of that of the overall loads/end loads,the network power losses and node voltage swing are both minimum when the PV/ESS is integrated to the head/tail end of the network.When the active power of the PV/ESS is between the above two conditions,nodes t/f can be identified for the integration of the PV between the head/end nodes of the network to achieve the minimum network power losses/voltage swing,respectively.The effectiveness of the proposed optimization approach is verified and can provide a reference for selecting the PV location in the distribution network.3)The influence of centralized storage location and capacitance on power losses and voltage swing of distribution network with PV grid integration is studied.An improved particle swarm optimization(PSO)algorithm based on elite set is proposed to solve the problem that PSO is prone to fall into local optimum,by adding the population convergence function and the inertia weight updating function to expand the population dispersion.The improved PSO Algorithm improves the global search ability of the algorithm,and optimize the algorithm flow,a centralized energy storage location and capacity optimization scheme is proposed.Taking 14 nodes as an example,a distribution network planning model with multi-PV and centralized energy storage is established,and an optimization method of centralized energy storage location and capacity is proposed.