Research On Load Transfer Capacity Of Distribution Network

As the terminal directly connected to the user in the power system,the distribution network bears the task of delivering power to the user's "last mile",which has a great influence on the quality and reliability of the user's power supply.In order to improve the reliability of load power supply after distribution network faults,this dissertation studies deeply the load transfer capability of distribution network.The main content of the paper is as follows:First,considering the influence of random factor fluctuations on distribution network power flow calculations,the stochastic power flow based on point estimation method is introduced into the research of power distribution network transfer capacity.The basic principles of point estimation method are introduced,and the probability distribution of state variables is obtained by using Gram-Charlier expansion series.Then,the topology of the distribution network is studied deeply and the common topology of the distribution network is introduced,take the main transformer interconnection matrix method to narrow down the search path for transfer.Based on this,the heuristic search algorithm is used to complete the topology search and the transfer plan is obtained.In order to find the optimal transfer program among multiple possible transfer options,a load transfer evaluation model is established,focusing on voltage quality,main transformer load ratio,number of switch operations,additional network loss,current level,and load loss.The subjective weights and objective weights are combined to determine the comprehensive weight of each index,the optimal load transfer program is then obtained through the grey correlation analysis method.The actual example in Yangzhou proves the effectiveness and practicability of the algorithm.Finally,in order to evaluate the capacity of regional power distribution network transfer and find out the weak links in the area,based on the risk theory,evaluation is made from the possibility and severity of the accident after the failure,and comprehensive risk indicators for each transfer plan are obtained,on this basis,it traverses all the lines of the distribution network and simulates the possibility of failure.In this case,the area with high probability of accidents in the power grid is obtained and targeted reconstruction is carried out to reduce its risk.By verifying the example of distribution system in Yangzhou,the correctness and feasibility of the algorithm are shown.