Research On Optimal Placement And Regulation Of Energy Storage In Distribution Network Adapting To Complex Characteristics Of Net Load

With the proposal of national carbon peaking and carbon neutrality goals,clean replacement and low-carbon environmental protection have gradually become popular research contents,making the penetration ratio of photovoltaic power generation systems and electric vehicles in the distribution network higher and higher.However,the output of the photovoltaic system has a strong correlation with the light intensity and weather conditions,but these factors have strong uncertainty and randomness.On the one hand,it seriously threatens the safe and stable operation of the distribution network;on the other hand,the output of the photovoltaic system has obvious timing characteristics,which makes the original load curve appear "duck curve" phenomenon.The electric vehicle load is closely related to the travel behavior of the car owner.Compared with the traditional load,there is a certain degree of uncertainty.At the same time,when the load penetration rate of electric vehicles reaches a certain level,the disordered charging load characteristics will change the peak-valley time characteristics of the original load,making the original load curve appear peak-to-peak.The connection of photovoltaic power generation systems and electric vehicle loads greatly changes the net load characteristics of the distribution network,and at the same time poses severe challenges to the operation of the distribution network.It has important theoretical significance and application value to study the complex characteristics of the net load of the distribution network,optimize the placement and regulation of energy storage equipment,and ensure the safe and economic operation of the distribution network.In this paper,the net load characteristics of the distribution network are studied.The main work and research results are as follows:(1)Analysis of complex characteristics of distribution network net load.First of all,through the data analysis of typical passenger car travel,obtains the electric vehicle mileage and start charging time two important probability distributions.Then,the Monte Carlo simulation method is used to obtain the charging load data of electric vehicles for one year.Then one year’s normalized PV output,base load and EV load data form a combined source-load datasets;In order to avoid the subjectivity of artificially selecting the number of clusters,the elbow method is used to determine the optimal number of clusters in the joint datasets,and then the FCM clustering algorithm is used to cluster the source-load joint datasets to generate typical scene sets.Finally,the net load curve of each typical scenario is obtained through the source load curve of the typical scenario,and the indicators of the net load curve are analyzed.The complex characteristics of the net load of the distribution network when the large-scale photovoltaic system and the charging load of electric vehicles are connected to the grid are obtained.(2)Optimal placement of energy storage equipment in distribution network adapting to net load characteristics.In view of the complex characteristics of large-scale connection of PV and EV to the distribution system,which increases the fluctuation of net load,increases the peak-to-valley difference,and reduces the load rate,a multi-objective energy storage optimal placement model considering energy storage construction and operation cost,net load fluctuation and network loss is proposed,so as to improve the safe and economic operation of the power grid while considering the optimized net load characteristics;The multi-objective energy storage optimal placement model is solved by using the NSGA-Ⅲ algorithm,and finally the energy storage placement is obtained with the minimum net load fluctuation target.The validity of the placement of the energy storage equipment is verified by analyzing the change of the net load characteristics after the energy storage is connected.(3)Optimal regulation strategy of energy storage equipment to stabilize net load fluctuations.Firstly,the optimal regulation of energy storage equipment is described as an optimal power flow problem,and then a two-stage optimization regulation model of energy storage equipment is established.In the day-ahead energy storage regulation stage,energy storage is planned to reasonably moderate the net load of the distribution network based on the predicted results of renewable energy generation and load in the day-ahead energy storage network.To maximize the effect of energy storage to stabilize the net load,realize the net load prediction of the distribution network and reduce the fluctuation of the net load of the distribution network,solve various uncertain factors of internal regulation of distribution network to the maximum extent.Due to the existence of forecast errors,there will always be deviations between intra-day regulation and day-ahead regulation.The surplus reserve in energy storage system and the backup provided by the superior power grid are used to solve the deviation of intra-day regulation and day-ahead regulation,and the regulation problem of stabilizing the net load of the entire energy storage equipment is transformed into energy storage and superiors grid backup solves the problem of residual forecast deviation,achieves the goal of stabilizing the expected net load to the greatest extent.