Power Transformer No-Load Loss Prediction with FEM Modeling and Building Factor Optimization

Ehsan Hajipour, Pooya Rezaei, Mehdi Vakilian, Mohsen Ghafouri

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DOI: 10.4236/jemaa.2011.310068                

Abstract

Estimation of power transformer no-load loss is a critical issue in the design of distribution transformers. Any deviation in estimation of the core losses during the design stage can lead to a financial penalty for the transformer manufacturer. In this paper an effective and novel method is proposed to determine all components of the iron core losses applying a combination of the empirical and numerical techniques. In this method at the first stage all computable components of the core losses are calculated, using Finite Element Method (FEM) modeling and analysis of the transformer iron core. This method takes into account magnetic sheets anisotropy, joint losses and stacking holes. Next, a Quadratic Programming (QP) optimization technique is employed to estimate the incomputable components of the core losses. This method provides a chance for improvement of the core loss estimation over the time when more measured data become available. The optimization process handles the singular deviations caused by different manufacturing machineries and labor during the transformer manufacturing and overhaul process. Therefore, application of this method enables different companies to obtain different results for the same designs and materials employed, using their historical data. Effectiveness of this method is verified by inspection of 54 full size distribution transformer measurement data.

Keywords

Building Factor, Core Losses, Finite Element Method, Power Transformer

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	G. F. Mechler and R. S. Girgis, “Calculation of Spatial Loss Distribution in Stacked Power and Distribution Transformer Cores,” IEEE Transactions on Power Delivery, Vol. 13, No. 2, 1998, pp. 532-537. doi:10.1109/61.660925
[2]	P. S. Georgilakis, “Spotlight on Modern Transformer Design,” Springer-Verlag, New York, 2009. doi:10.1007/978-1-84882-667-0
[3]	NEMA Standard TP 1, Guide for Determining Energy Efficiency for Distribution Transformers, 2002.
[4]	CENELEC Standards HD 428.1, Three Phase Oil-immersed Distribution Transformers 50 Hz, from 50 kVA to 2500 kVA, with Highest Voltage for Equipment Not Exceeding 36 kV, 1992.
[5]	A. J. Moses, “Prediction of Core Losses of Three Phase Transformers from Estimation of the components Contributing to the Building Factor,” Journal of Magnetism and Magnetic Materials, Vol. 254-255, 2003, pp. 615- 617. doi:10.1016/S0304-8853(02)00911-3
[6]	A. Basak and, A. A. Bonyar, “Effects of transformer core assembly on building factors,” Journal of Magnetism and Magnetic Materials, Vol. 112, No. 1-3, 1992, pp. 406- 408. doi:10.1016/0304-8853(92)91214-E
[7]	K. A. L. Abdul-Retha and A. Basak, “A Comparison of Building Factors for Different Types of Transformer Cores Built With Highly Oriented and Conventional Grade Silicon-Iron Laminations,” Journal of Magnetism and Magnetic Materials, Vol. 26, No. 1-3, 1982, pp. 92- 94. doi:10.1016/0304-8853(82)90123-8
[8]	Z. Valkovic, “Additional Losses in Three-Phase Transformer Cores,” Journal of Magnetism and Magnetic Materials, Vol. 41, No. 1-3, 1984, pp. 424-426. doi:10.1016/0304-8853(84)90237-3
[9]	G. W. Swift, “Excitation current and Power Loss Characteristics for Mitered Joint Power Transformer Cores,” IEEE Transactions on Magnetic, Vol. 11, No. 1, 1975, pp. 61-64. doi:10.1109/TMAG.1975.1058541
[10]	M. Elleuch and M. Poloujadoff, “New Transformer Model Including Joint Air Gaps and Lamination Anisotropy,” IEEE Transactions on Magnetic, Vol. 34, No. 5, 1998, pp. 3701-3711. doi:10.1109/20.718532
[11]	M. Elleuch, M. Poloujadoff, “Analytical model of iron losses in power transformers,” IEEE Transactions on Magnetic, Vol. 39, No. 2, 2003, pp. 973-980. doi:10.1109/TMAG.2003.808591
[12]	C. Nussbaum, T. Booth, A. Ilo and H. Pfutzner, “A Neural Network for the Prediction of Performance Parameters of Transformer Cores,” Journal of Magnetism and Magnetic Materials, Vol. 160, No. 1, 1996, pp. 81-83. doi:10.1016/0304-8853(96)00122-9
[13]	C. Nussbaum, H. Pfutzner, Th. Booth, N. Baumgartinger, A. Ilo and M. Clabian, “Neural Networks for the Prediction of Magnetic Transformer Core Characteristics,” IEEE Transactions on Magnetic, Vol. 36, No. 1, 2000, pp. 313-329. doi:10.1109/20.822542
[14]	E. Hajipour, M. Vakilian and S. A. Mousavi, “A Novel Fast FEA No-Load Loss Calculation Method for Stacked Core Three Phase Distribution Transformers,” 45th International Universities Power Engineering Conference, Cardiff, 2010, unpublished.
[15]	R. Prieto, J. A. Cobos, V. Bataller, O. Garcia and J. Ucedci, “Study of Toroidal Transformers by Means of 2D Approaches,” Proceeding of 28th IEEE Annual Power Electronics Specialists Conference, St. Louis, 22-27 June 1997, pp. 621-626.
[16]	G. F. Mechler and R. S. Girgis, “Magnetic Flux Distribution in Transformer Core Joints,” IEEE Transactions on Power Delivery, Vol. 15, No. 1, 2000, pp. 198-203. doi:10.1109/61.847251
[17]	E. G. teNyenhuis, R. S. Girgis and G. F. Mechler, “Other Factors Contributing to the Core Loss Performance of Power and Distribution Transformers,” IEEE Transactions on Power Delivery, Vol. 16, No. 4, 2001, pp. 648- 653. doi:10.1109/61.956752
[18]	NEMA Standard TP 2, Standard Test Method for Measuring the Energy Consumption of Distribution Transformers, 2005.
[19]	M. Enokizono and N. Soda, “Finite Element Analysis of Transformer Model Core with Measured Reluctivity Tensor,” Transactions on Magnetic, Vol. 33, No. 5, 1997, pp. 4110-4112.
[20]	A. Ilo, H. Pfutzner and T. Nakata, “Critical Induction: A Key Quantity for the Optimization of Transformer Core Operation,” Journal of Magnetism and Magnetic Materials, Vols. 215-216, No. 1, 2000, pp. 637-640. doi:10.1016/S0304-8853(00)00248-1
[21]	J. C. Olivares, Y. Liu, J. Canedo, R. Escarela-Perez, J. Driesen and P. Moreno, “Reducing Losses in Distribution Transformers,” IEEE Transactions on Power Delivery, Vol. 18, No. 4, 2003, pp. 821-826. doi:10.1109/TPWRD.2003.813851
[22]	S. A. Mousavi, “Harmonic Core Losses Calculation in Power Transformers,” M.Sc. Thesis, University of Tehran, Tehran, 2008.
[23]	W. A. Roshen, “A Practical, Accurate and Very General Core Loss Model for Non-Sinusoidal Waveforms,” IEEE Transactions on Power Electronics, Vol. 22, 2007, pp. 30-40. doi:10.1109/TPEL.2006.886608
[24]	A. J. Moses, “Comparison of Transformer Loss Prediction from Computed and Measured Flux Density Distribution,” IEEE Transactions on Magnetic, Vol. 34, No. 4, 1998, pp. 1186-1188. doi:10.1109/20.706473
[25]	F. Loffer, T. Booth, H. Pfutzner, C. Bengtsson and K. Gram, “Relevance of Step-Lap Joints for Magnetic Characteristics of Transformer Cores,” IEE Proceeding in Electric Power Application, Vol. 142, No. 6, 1995, pp. 371-378.doi:10.1049/ip-epa:19952228
[26]	M. R. Pishvaie, “Process Optimization Course” 2010. http://sharif.ir/~pishvaie/OptimCoursePage.htm.
[27]	Z. Valkovic, “Influence of Transformer Core Design on Power Losses,” IEEE Transactions on magnetic, Vol. 18, No. 2, 1982, pp. 801-804. doi:10.1109/TMAG.1982.1061824