Study and Analysis of the Effect of Harmonics on the Hot Spot Temperature of a Distribution Transformer Using Finite-Volume Method |
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Authors: | Mabel Ebenezer Rajkumar Mattacaud Ramachandralal Chandramohanan Nair Padmanabha Pillai Sarasamma |
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Affiliation: | 1. Department of Electrical Engineering, College of Engineering, Trivandrum, Kerala, India;2. Department of Mechanical Engineering, College of Engineering, Trivandrum, Kerala, India;3. Department of Electrical Engineering, Amrita School of Engineering, Amrita University, Kollam, Kerala, India |
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Abstract: | Transformers are critical components in power systems and their failure can cause long interruption of power supply. The condition of a transformer can be monitored by performing thermal analysis. The use of non-linear devices, such as rectifiers and converters, draws harmonic currents that increase losses in transformers, thereby increasing their operating temperature. In this article, a new numerical approach is presented for determining the rise in hot spot temperature in a 5-kVA, 400/400-V dry-type three-phase transformer laboratory prototype. The key novelty is that the additional winding eddy current loss due to non-linear loads is considered in the numerical modeling. The winding eddy current loss corresponding to harmonic distortion is estimated by conducting experiments and calculations. Numerical simulations are carried out for a wide range of non-linear loads using a commercial computational fluid dynamics package, FLUENT 6.3. The proposed numerical methodology is validated by performing experiments on the transformer for possible non-linear loads and comparing the measured hot spot temperature with the simulated values. Correlation equations for rise in hot spot temperature as a function of total harmonic distortion are presented, which can be used for estimating the life of transformers when connected to different types of loads. |
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Keywords: | dry-type three-phase transformer hot spot temperature total harmonic distortion dimensionless temperature rise |
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