Detection And Analysis Of Three-phase Unbalance Of Distribution Transformer

Power plays an important role in the development of social economy and our daily life,otherwise,it is also a powerful driving force to promote the development of national industry,science,technology and social stability.With the development of science,technology and the national economy,it appears all kinds of load in the grid.At the same time,people pay more and more attention to power quality.Power quality is usually characterized by the frequency,offset,fluctuation,flicker,discontinuity,collapse,spikes,harmonics,distortion,three-phase unbalance and high frequency interference of the supply voltage,and the three-phase unbalance is one of the important indexes of power quality.As the low-voltage load commonly used three-phase four-wire wiring,coupled with the random load of single-phase load,resulting three-phase load of distribution transformer in a long-term unbalanced.This will cause s series of problems such as three-phase voltage unbalanced,zero sequence current is too large,the distribution transformer local heat and so on,thereby it may reduce the motor active power output,reduce the transformer output and increase the loss of distribution lines.More of worse,it may even burn off the zero line and damage the user's electrical equipment.Power quality is important for the safe and economic operation of power grid and electrical equipment,and it is important to ensure the quality of production and the normal order of people's life.Aimed at the three-phase unbalance of distribution transformer in Jiaozuo,Henan Province,this paper studies the causes and harms of the distribution transformer three-phase unbalance deeply,and summarizes the calculation method of three-phase unbalance factor.Design power quality testing device,carry out field research and detection,select 30 distribution transformer points as the detection of objects which are distributed among the industrial area,residential area,business district,urban and rural areas,and finally get a lot of field test data.Then write an analysis software through LabVIEW,analysis the distribution transformer three-phase unbalance and load characteristics deeply.Use MATLAB to establish a simulationmodel of low voltage load,find out the characteristics and causes of the three-phase unbalance problem of distribution transformer in Jiaozuo,Henan Province through compared the simulation results with the analysis results of field test data.Finally,give the method and measures to control the three-phase unbalance of distribution transformer from management and technology aspects.