Research Of Distribution Transformer Winding Fault Online Diagnosis Method

Distribution transformer performs the important task of voltage transform andpower distribution in the power distribution system. It’s safe and reliable operation is ofgreat significance to ensure the stable operation of power distribution system. Due todistribution power network planning, construction and present development situation,distribution transformer operation conditions is in serious and winding faults oftenhappen. Distribution transformer maintenance take planned maintenance as theprincipal thing, which affects distribution network power supply reliability and powerquality, so it is of great significance to present a kind of on-line distribution transformerwinding fault diagnosis method which is suitable for condition based maintenance. Dueto the existing fault detection is not suitable for distribution transformer windings faultdiagnosis and the lack of diagnostic basis and quantitative standards of distributiontransformer winding fault, so it is of vital significance to positive analysis and calculatetransformer internal electromagnetic parameters and winding current and short-circuitimpedance when transformer is in fault, and establish fault diagnostic basis andquantitative standards, and reverse diagnosis winding fault through windingshort-circuit impedance which is calculated by winding current and voltage.Based on the investigation of distribution transformer winding faults andtransformer parameter model, this paper set up the static magnetic field and thefield-circuit coupling transient model which based on the finite element method. Andthis paper use ANSOFT to calculate transformer leakage magnetic field distribution,winding electromotive force, winding current and the equivalent winding short-circuitimpedance when transformer is in winding short circuit, winding insulation aging andwinding deformation failure, which provide the diagnostic basis and quantitativestandards for distribution transformer winding fault diagnosis. Winding fault on-linediagnosis system whose method based on winding short-circuit impedance parameterwhich is calculated through winding terminal current and voltage is established. Theexactness of the winding fault diagnosis system is verified through the transformeradjustable hood check. In this paper, the main contents are as follows:①This paper briefly describes background and significance of distributiontransformer winding fault diagnosis, and state transformer parameter model andwinding fault diagnosis research present situation, and determine transformer winding fault diagnosis method, and survey transformer winding fault types and causes.②Transformer static magnetic field model and field-circuit coupling transientmodel are established. Static magnetic field model is used to calculate transformerleakage magnetic field distribution and winding electromotive force when transformeris in no-load and rated-load and external short circuit. Field-circuit coupling model isused to calculate transformer internal electromagnetic parameters and windingterminal current and equivalent short-circuit impedance. Short-circuit test is used toprove the validity of the field-circuit coupling model.③Distribution transformer windings turn-to-turn short circuit and winding shortto ground fault field-circuit coupling model is established to positive calculatetransformer leakage magnetic field distribution, winding electromotive force, windingcurrent and equivalent short circuit impedance, which provide diagnostic basis andquantitative standards for winding short-circuit fault on-line diagnosis.④Distribution transformer winding axial displacement deformation and windingpotential insulation ageing fault field-circuit coupling model is established to positivecalculate transformer leakage magnetic field distribution, winding electromotive force,winding current and winding equivalent short circuit impedance, which is used toprovide diagnostic basis and quantitative standards for winding potential fault on-linediagnosis.⑤Transformer winding fault on-line diagnosis system which based onshort-circuit impedance that is calculated through winding terminal current and voltageparameters is established to reverse diagnose winding fault. Experimental platform isestablished to verify the accuracy of on-line short-circuit impedance measurement.Error analysis is done through Matlab simulink.⑥Transformer winding fault on-line diagnosis platform is established. Theaccuracy of on-line winding fault diagnosis method is verified through windingshort-circuit impedance measurement and transformer adjustable hood inspection.