Diagnostic Gas Analysis

Condition Monitoring of Power Transformers Using DGA and Neuro-Fuzzy Logic

Presented By:Rahul PandeyM.E. 4th Semester (Electrical)SSGI Bhilai (CG)Guided By:Prof. M.T.DeshpandeSr.Associate ProfessorSSGI Bhilai (CG)18/10/2013 1118/10/2013ContentIntroductionObjective of Project WorkLiterature SurveyMechanism of gas generationInterpretation of DGAResidual Life AssessmentResult and DiscussionsConclusion

18/10/2013 2IntroductionTransformer oil is one of the most common materials used for transformers. When the mineral oil is subjected to high thermal and electrical stress, gases are generated from the decomposition of the mineral oil.Different type of faults will generate different gases and the analysis of these gases will provide useful information about the condition of the oil and the identification of the type of fault in the transformer. The chemical analysis of these gases is called dissolved gas analysis or DGA.

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Objective of Project Work

Advance warning of developing faults. Determining the improper use of units. Status checks on new and repaired units.Convenient scheduling of repairs.Monitoring of units under overload.To introduce a mechanism to reduce time consuming data analysis.

18/10/2013 4Literature Survey 18/10/2013 5S.NOAUTHORSPAPER TITLEPUBLICATION /YEARCONCLUSION(i)R.Rogers IEEE and IEC codes to interpret incipient faults in transformerIEEE ,1978.Discussed the gases produced during the deterioration of mineral oil and cellulose were examined and techniques were established to assist in the interpretation of the type of fault, incipient or growing, occurring within the transformer.(ii)Q. Su, C. Mi, L. L. Lai and P. Austin A Fuzzy Dissolved Gas Analysis Method for the Diagnosis of Multiple Incipient Faults in a TransformerIEEE ,2000Discussed the fuzzy logic technique which can diagnose multiple faults in a transformer and quantitatively indicates the likelihood severity of each fault.(iii)M.Ahfaz Khan and Dr.A.K.Sharma

Transformer Failure Rate Prediction Based on Condition AssessmentIJSR,2013Discussed the Condition monitoring has traditionally been done manually by the use of various diagnostic checks. Examples include the levels and types of oil condition, winding condition, insulation condition and physical condition of transformer and timing or operating checks on mechanical equipment etc.

18/10/2013 6618/10/2013S.NOAUTHORSPAPER TITLEPUBLICATION /YEARCONCLUSION(iv)Akgundogu Abdurrahim ,qozutok Abdulkadir, Killic Niyazi,Ucan Osman N.Fault diagnosis of power transformer using neuro-fuzzy modelJournal of EEE,2008This paper proposes a fuzzy-neural method to perform self-learning and auto rule-adjustment for producing the best rules. Test using the hybrid diagnosis system are satisfactory.(v)M. Duval Dissolved gas analysis: It can save your transformer,IEEE,1989Discussed the use of dissolved gas analysis (DGA) to monitor the in-service behaviour of transformers.(vi)Balint nemeth,Szilivia Laboncz and Istvan kiss Condition Monitoring of Power Transformers using DGA and Fuzzy Logic IEEE ,2009In the paper it was presented how a fuzzy logic approach of DGA can be applied for a certain problem. Steps of the application including the analysis of the working process, determination of the parameters to be monitored and the fuzzy logic based evaluation of their values.18/10/2013 7Types of faultsInsulation overheating -When transformer is overloaded it generates more heat and deteriorates the cellulose insulation. In this case DGA results show high carbon monoxide and high carbon dioxide. In extreme cases methane and ethylene are at higher levels.Insulation liquid overheating -The overheating of insulation liquid results in breakdown of liquid by heat and formation of high thermal gases. They are methane, ethane and ethylene.Corona -It is a partial discharge and detected in a DGA by elevated hydrogen.Arcing -It is the most severe condition in a transformer and indicated even by low levels of acetylene.18/10/2013 8Mechanism of Gas GenerationGases in oil always result from the decomposition of electrical insulation materials (oil or paper), as a result of faults or chemical reactions in the equipment.

For example, oil is a molecule of hydrocarbons, i.e., containing hydrogen and carbon atoms, linked by chemical bonds (C-H, C-C).18/10/2013 9Fault Gasses When gassing occurs in transformers there are several gasses that are created. Enough useful information can be derived from nine gases so the additional gasses are usually not examined. The nine gasses examined are:Atmospheric Gases: hydrogen, nitrogen and oxygen

Oxides of Carbon: carbon monoxide and carbon dioxide

Hydro Carbons: acetylene, ethylene, methane and ethane

18/10/2013 10Interpretation of DGA 18/10/2013 11IEC 599- Gas Ratio CodesThe IEC599-Gas Ratio Code MethodC2H2/C2H4CH4/H2C2H4/C2H6Code of Range of Ratios010=0.1 ~ =1 ~ =3Code CombinationCharacteristic Fault000Normal Ageing001Thermal Fault of Low Temperature700C.102Discharge of High Energy (Arcing).010Discharge of Low Energy (P.D).110Discharges of Low Energy (P.D).1-201-2Discharge of Low Energy.18/10/2013 12Extended IEC 599 CodesAlthough IEC codes were developed to diagnose transformer faults, there are situations of errors and misleading results occurring due to borderline and multiple faults.

IEC codes are extended into expert rules using experiences in the field by filling in the gaps created by IEC.18/10/2013 13

Extended IEC 599 DGA Codes Code of Range of RatiosCode for different gas ratiosC2H2/C2H4CH4/H2

C2H4/C2H6

322218/10/2013 14Fault Description Fault TypeFault DescriptionC2H2/C2H4CH4/H2C2H4/C2H6HEDA 1High Energy Discharge and Arcing20 or 2X HEDA 210 or 2XLED1Low Energy Discharge21XLED211XPDPartial Discharge01XNormalNormal Aging Condition000OHT 1Low Temperature Overheating T