Analysis of excessive hydrogen generation in transformers in service

The paper concerns the case study of a group of oil power transformers in which, on the basis of the measurements of concentration of gases dissolved in oil, excessive generation of hydrogen was noticed. Analysis performed using the ratio method proposed by IEC 60599 standard, and the Duval triangle method, identified partial discharge (PD) generation in the transformer units considered. Deepened analysis indicated however that such a diagnosis may by false and excessive hydrogen generation is a result of stray gassing. Additional studies such as the measurements of partial discharge intensity using acoustic emission method as well as internal inspection and factory tests (including PD measurements using electrical method) of selected units seem to confirm this hypothesis. However, taking into account the recommendations described in CIGRE brochure 296, lack of compatibility of constructional materials with the oil used in the analyzed group of transformers is also probable. Finally, this may be concluded that assessment of the results of the DGA needs to be carried out carefully when an increase in the concentration of hydrogen in the transformers in service is observed. An unambiguous determination of the cause of the fault cannot be indicated only on the basis of basic analysis. Some other, more specific analyses and tests should be used.

[1]  Jian Li,et al.  Canonical Correlation Between Partial Discharges and Gas Formation in Transformer Oil Paper Insulation , 2012, Energies.

[2]  J. L. Guardado,et al.  A Comparative Study of Neural Network Efficiency in Power Transformers Diagnosis Using Dissolved Gas Analysis , 2001, IEEE Power Engineering Review.

[3]  Ieee Standards Board.  IEEE guide for the interpretation of gases generated in oil-immersed transformers , 1992 .

[4]  Michel Duval.  Dissolved Gas Analysis and the Duval Triangle By , 2006 .

[5]  Tomasz Boczar,et al.  Diagnostic expert system of transformer insulation systems using the acoustic emission method , 2014, IEEE Transactions on Dielectrics and Electrical Insulation.

[6]  I. Hohlein,et al.  Unusual cases of gassing in transformers in service , 2006, IEEE Electrical Insulation Magazine.

[7]  B. Noirhomme,et al.  Unusual ethylene production of in-service transformer oil at low temperature , 2012, IEEE Transactions on Dielectrics and Electrical Insulation.

[8]  T. Boczar.  Identification of a specific type of PD from acoustic emission frequency spectra , 2001 .

[9]  M. Duval,et al.  The duval triangle for load tap changers, non-mineral oils and low temperature faults in transformers , 2008, IEEE Electrical Insulation Magazine.

[10]  M. Duval,et al.  Improving the reliability of transformer gas-in-oil diagnosis , 2005, IEEE Electrical Insulation Magazine.

[11]  Whei-Min Lin,et al.  Study of Partial Discharge Measurement in Power Equipment Using Acoustic Technique and Wavelet Transform , 2007, IEEE Transactions on Power Delivery.

[12]  J. Rolim,et al.  A hybrid tool for detection of incipient faults in transformers based on the dissolved gas analysis of insulating oil , 2006, 2006 IEEE Power Engineering Society General Meeting.

[13]  Michel Duval,et al.  A review of faults detectable by gas-in-oil analysis in transformers , 2002 .