Condition assessment of cellulosic part in power transformer insulation using transfer function zero of modified debye model

Analysis of Polarization-Depolarization Current, recorded from high voltage oil-paper insulation using insulation model is common among researchers. It is reported that paper insulation of power transformers undergoes non-uniform aging. Unlike Conventional Debye Model (CDM), Modified Debye Model (MDM) is capable of modeling such non-uniform aging. However, factors like insulation geometry affect the values of the MDM branch parameters. Therefore, model parameterized using data obtained from one insulation system finds limited use in assessing the condition of a different transformer, even with similar loading history and power rating. The present paper shows that a performance parameter, which is less sensitive to insulation geometry, can be evaluated from Transfer Function, TFM(s) of MDM. The parameter is the zero Z1 of TFM(s) which is located farthest away from the origin in the Left Half Plane of s-plane. The capability of Z1 as an insulation condition sensitive parameter is first tested on laboratory samples and then on data recorded from several real life power transformers. Results obtained for these transformers show that there is a good correlation between magnitude of Z1 and paper moisture content obtained from Frequency Domain Spectroscopy (FDS) using IDAX 300.

[1]  Dennis S. Bernstein,et al.  Matrix Mathematics: Theory, Facts, and Formulas with Application to Linear Systems Theory , 2005 .

[2]  P. Purkait,et al.  Deriving an equivalent circuit of transformers insulation for understanding the dielectric response measurements , 2005, IEEE Transactions on Power Delivery.

[3]  M. Pompili,et al.  Corrosive Sulfur Induced Failures in Oil-Filled Electrical Power Transformers and Shunt Reactors , 2009, IEEE Transactions on Power Delivery.

[4]  W. Zaengl,et al.  On-site diagnosis of power transformers by means of relaxation current measurements , 1998, Conference Record of the 1998 IEEE International Symposium on Electrical Insulation (Cat. No.98CH36239).

[5]  Tapan Kumar Saha,et al.  Review of modern diagnostic techniques for assessing insulation condition in aged transformers , 2003 .

[6]  Hassan Ezzaidi,et al.  On the Feasibility of Using Poles Computed from Frequency Domain Spectroscopy to Assess Oil Impregnated Paper Insulation Conditions , 2013 .

[7]  F Meghnefi,et al.  On the frequency domain dielectric response of oil-paper insulation at low temperatures , 2010, IEEE Transactions on Dielectrics and Electrical Insulation.

[8]  S. Chakravorti,et al.  Assessment of non-uniform aging of solid dielectric using system poles of a modified debye model for oil-paper insulation of transformers , 2013, IEEE Transactions on Dielectrics and Electrical Insulation.

[9]  Jesse B. Hoagg,et al.  Nonminimum-phase zeros - much to do about nothing - classical control - revisited part II , 2007, IEEE Control Systems.

[10]  W. S. Zaengl,et al.  Dielectric Response Methods for Diagnostics of Power Transformers , 2003 .

[11]  Shuzhen Xu,et al.  A comparison of Return voltage measurement and frequency domain spectroscopy test on high voltage insulation , 2003, Proceedings of the 7th International Conference on Properties and Applications of Dielectric Materials (Cat. No.03CH37417).

[12]  C. Ekanayake,et al.  Application of polarization based measurement techniques for diagnosis of field transformers , 2010, IEEE PES General Meeting.

[13]  P. Purkait,et al.  Investigations of Temperature Effects on the Dielectric Response Measurements of Transformer Oil-Paper Insulation System , 2008, IEEE Transactions on Power Delivery.

[14]  G. Csepes,et al.  Practical foundations of the RVM (recovery voltage method for oil/paper insulation diagnosis) , 1998, 1998 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.98CH36257).

[15]  L. Adeen,et al.  Dielectric spectroscopy in time and frequency domain applied to diagnostics of power transformers , 2000, Proceedings of the 6th International Conference on Properties and Applications of Dielectric Materials (Cat. No.00CH36347).

[16]  C. D. Halevidis,et al.  Calculation of the activation energy of oil-paper insulation in a distribution transformer , 2012, IEEE Electrical Insulation Magazine.

[17]  H. Borsi,et al.  PDC measurement evaluation on oil-pressboard samples , 2004, Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004. ICSD 2004..

[18]  P. Purkait,et al.  Investigation of an expert system for the condition assessment of transformer insulation based on dielectric response measurements , 2004, IEEE Transactions on Power Delivery.

[19]  Walter S. Zaengl,et al.  DIELECTRIC SPECTROSCOPY IN TIME AND FREQUENCY DOMAIN FOR HV POWER EQUIPMENT (TRANSFORMERS, CABLES ETC.) , 2001 .

[20]  W. S. Zaengl,et al.  Time domain measurements of dielectric response in oil-paper insulation systems , 1996, Conference Record of the 1996 IEEE International Symposium on Electrical Insulation.

[21]  V. Der Houhanessian,et al.  Application of relaxation current measurements to on-site diagnosis of power transformers , 1997, IEEE 1997 Annual Report Conference on Electrical Insulation and Dielectric Phenomena.

[22]  W. S. Zaengl,et al.  Dielectric spectroscopy in time and frequency domain for HV power equipment. I. Theoretical considerations , 2003 .

[23]  S. Chakravorti,et al.  A modified Maxwell model for characterization of relaxation processes within insulation system having non-uniform aging due to temperature gradient , 2013, IEEE Transactions on Dielectrics and Electrical Insulation.

[24]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[25]  W.S. Zaengl,et al.  Applications of dielectric spectroscopy in time and frequency domain for HV power equipment , 2003, IEEE Electrical Insulation Magazine.