Research On The Optimal Configuration Of Distributed Energy Storage Based On Hierarchical And Partitioned

With the increase of the proportion of photovoltaic(PV),wind power and other renewable energy in the distribution network,the randomness and uncertainty of its output will have a certain impact on the safety and stability of the power grid.When the output power is relatively large,wind curtailment and PV curtailment will occur,resulting in output power waste.Moreover,with the development of social economy,the load peak-valley power difference gradually increases,and the equipment utilization rate decreases,which affects the economy of power grid.In addition,the traditional power system technology has been unable to adapt to the complex distribution network system.Energy storage technology can effectively solve the problems existing in the distribution network due to its flexible access position,strong power handling capacity and fast response rate.However,because of the cost and technology,the energy storage system(ESS)has not been widely used.In this context,the distributed energy storage system(DESS)in distribution network is taken as the research object,starts from the actual problems of power grid,and based on the idea of hierarchy and partition,studies the optimal allocation of DESS to improve the rationality of configuration.It Mainly includes the following aspects:For the optimal location of ESS problem,a method of energy storage location based on load characteristics and voltage sensitivity is proposed.Substation ESS location selection: according to the load rate of the substation,the load peak-valley power difference,the important load power and the load fluctuation,the ESS site selection indices of the substation is constructed.Based on the indices,the ESS access location of the substation is selected according to the priority order,so as to balance the power of the grid and stabilize the load curve.Feeder DESS location selection: Based on weighted voltage sensitivity,an optimization model of DESS access location on feeders is proposed to improve the distribution of feeders' voltage.Moreover,the validity of the proposed site selection method is verified by an example.Aiming at the problem of optimal configuration of ESS capacity based on partition,a method of capacity optimization based on improved flame propagation model is proposed.The ground load distribution network type,network topology,and other factors,such as ESS power limit are considered in this thesis,and the introduction of combustible nodes,such as flame propagation direction,the flame propagation speed indicator coordinated optimization of ESS capacity,service radius and the relations between and among economic benefit,establish energy storage partition method based on flame propagation model.Based on the partition of ESS,a practical method to solve ESS power is presented which is on the basis of power gaps.Then,on the premise that the ESS power is given,the power benefit,reliability benefit and electricity price benefit are taken into comprehensive consideration to establish the ESS capacity optimization model with the maximum annual net profits as the objective function.The feasibility and effectiveness of the proposed partitioning method and capacity optimization model are verified by the IEEE 33 node distribution network system.In view of the structural characteristics of hierarchical distribution of ESS,an aggregator ESS capacity optimization model based on users' aggregation evaluation was proposed.The idea of hierarchical ESS capacity optimization is introduced,and the power distribution of DESS is evaluated.Then,a DESS aggregation model based on the herd mentality is established to evaluate the functional relationship between subsidies and participation.The capacity optimization model of the aggregator ESS participating in the peak regulation of power grid based on users' aggregation evaluation is established,and the correctness of the proposed model is verified by an example.