Research On Load Characteristic And Economical Capacity Of Distribution Transformers In The Urban Distribution Network

With the continuous improvement of people's living standard in our country and the continuing adjustment of industrial structure.The growth rate of power load in distribution network is speeding up gradually.The load type and the characteristics can't be analysed easily.Distribution transformers' capacities in many parts are bigger than what we needs to avoid overload.The maximum load rate in some parts is less than 7%,which increase the initial investment and the fixed loss of distribution transformer.Armed at the problems aboved,some kinds of typical load characteristic in urban distribution network is analysed in this paper,based on which the load forecasting model is studied.Then the distribution transformers' capacities can be caculated by the demand factor table,according to which a software for selecting distribution transformer capacity is designed.Finally we use the comprehensive costs method to choose the suitable distribution transformers.Firstly,in order to get the time and change rules of maximum power load,the residential,commercial,hospitals' and universities' load is analysed by years,seasons,months and days.Then we can analyse the load characteristics such as load rate and peak-valley rate.The correlation between various meteorological factors and the power load is analyzed and the influence of temperature on load is analyzed emphatically.Secondly,the load curves which fit the measured data are manufactured by Kernel density estimation method.According to analysing the curvers,we can get the calculating power load and the demand factor table,by which we can obtain the corresponding distribution transformer capacity.Then a software for calculating distribution transformer capacity from the load characteristics is designed.At last,we should formulate distribution transformer options according to the established distribution transformer capacity,transformer types,substations,lines,load change,the time value of money and other factors.The best alternatives can be chosen by the comprehensive analysis and calculation of comprehensive costs for each scheme.In this paper,we choose distribution transformers by analysing the load characteristics,caculating the distribution transformer capacity and choosing the suitable transformer option.The problems that many distribution transformers' capacities are too large and economic benefit is low can be solved appropriately by these processes.This is a valuable reference for selecting the economic capacity of distribution transformers.