A Simplified Top-Oil Temperature Model for Transformers Based on the Pathway of Energy Transfer Concept and the Thermal-Electrical Analogy

Muhammad Hakirin Roslan, Norhafiz Azis, Mohd Zainal Abidin Ab Kadir, Jasronita Jasni, Zulkifli Ibrahim and Azalan Ahmad
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Muhammad Hakirin Roslan: Faculty of Engineering, Universiti Pertahanan Nasional Malaysia, Kem Sg Besi 57000, Malaysia
Norhafiz Azis: Centre for Electromagnetic and Lightning Protection Research, Universiti Putra Malaysia, Serdang 43400, Malaysia
Mohd Zainal Abidin Ab Kadir: Centre for Electromagnetic and Lightning Protection Research, Universiti Putra Malaysia, Serdang 43400, Malaysia
Jasronita Jasni: Centre for Electromagnetic and Lightning Protection Research, Universiti Putra Malaysia, Serdang 43400, Malaysia
Zulkifli Ibrahim: Centre for Electromagnetic and Lightning Protection Research, Universiti Putra Malaysia, Serdang 43400, Malaysia
Azalan Ahmad: Malaysia Transformer Manufacturing Sdn. Bhd, Ampang 54200, Selangor, Malaysia

Energies, 2017, vol. 10, issue 11, 1-15

Abstract: This paper presents an alternative approach to determine the simplified top-oil temperature (TOT) based on the pathway of energy transfer and thermal-electrical analogy concepts. The main contribution of this study is the redefinition of the nonlinear thermal resistance based on these concepts. An alternative approximation of convection coefficient, h , based on heat transfer theory was proposed which eliminated the requirement of viscosity. In addition, the lumped capacitance method was applied to the thermal-electrical analogy to derive the TOT thermal equivalent equation in differential form. The TOT thermal model was evaluated based on the measured TOT of seven transformers with either oil natural air natural (ONAN) or oil natural air forced (ONAF) cooling modes obtained from temperature rise tests. In addition, the performance of the TOT thermal model was tested on step-loading of a transformer with an ONAF cooling mode obtained from previous studies. A comparison between the TOT thermal model and the existing TOT Thermal-Electrical, Exponential (IEC 60076-7), and Clause 7 (IEEE C57.91-1995) models was also carried out. It was found that the measured TOT of seven transformers are well represented by the TOT thermal model where the highest maximum and root mean square (RMS) errors are 6.66 °C and 2.76 °C, respectively. Based on the maximum and RMS errors, the TOT thermal model performs better than Exponential and Clause 7 models and it is comparable with the Thermal-Electrical 1 (TE1) and Thermal-Electrical 2 (TE2) models. The same pattern is found for the TOT thermal model under step-loading where the maximum and RMS errors are 5.77 °C and 2.02 °C.

Keywords: top-oil temperature thermal model; pathway of energy transfer; thermal-electrical analogy; nonlinear oil thermal resistance; transformers (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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