Study On Detection Method Of Power Transformer Winding Deformation

Power transformer plays a very important role in the power supply,which can guarantee the normal operation of the power supply stability and reliability.In addition to the production process or transport,winding deformation will occur,but in the event of a large current fault,due to the role of electric power,electric power transformer winding deformation may also occur after deformation,even if the transformer is not damaged,it could be a security risks,such as:insulation part is damaged,resulting in partial discharge,over-voltage action in the likely breakdown occurs,causing the accident;when a short circuit fault occurs again,could withstand the force of the winding,and the occurrence of serious damage.Because in the daily operation,the frequency of occurrence of accidents is relatively high short-circuit other accidents,so the possibility of power transformer winding deformation will be enormous,so the study of transformer winding deformation detection technology,production and use of electric power transformer business,has a very significance.Current transformer winding deformation detection methods,including:low-pulse method,short circuit impedance,frequency response method,capacitance testing method,in which short-circuit impedance method can be used for online measurement,the test environment is not affected significantly,test indicators clear,However,the sensitivity of the poor,frequency response method for testing winding deformation,the higher degree of sensitivity,a slight deformation measurement error is small,but in the measurement process,anti-interference ability is relatively poor,higher capacity requirements for testers,its measurement indicators are not clear,can only be used off-line measurement;capacitance method can measure the displacement characteristics winding.Combining the advantages of the three,a comprehensive detection method is proposed,that is,in the daily operation,using the method line short-circuit impedance measured rate of change of the measured impedance transformer windings,when exceeds the set threshold,the transformer exit run time,then its frequency response test and capacitance test.This article will be divided into deformation,not deformation,a slight deformation,deformation,severely deformed,four deformation stages for discussion.The article first analyzes the relationship between geometry and winding space between the short-circuit impedance,indicating that the line impedance measurement method and the measurement system is designed,and then to determine the rate of change of short-circuit impedance winding deformation,based on the rate of change of the short-circuit impedance has been obtained between deformation and historical data,forming the membership function,using the principle of maximum membership degree of fuzzy math to determine the degree of deformation of the winding.In the case of short-circuit resistance sentenced to resist,using frequency response method further off-line testing,introduced the principle of frequency response method and criteria.Using the method proposed by this paper,we tested two transformers for a long-term.Experimental results demonstrate the effectiveness of this method.