Adequate voltage in the medium and low voltage electrical network is a mandatory issue. The transformers tap- changer (TC) is used to achieve this vital issue. The increasing of the power demand and the integration of the distributed generation with the electrical grid led to adjusting the TC of the transformer. Adjusting TC leads to adjusting the thermal parameters of the transformer, which affect directly the winding hottest spot temperature of the transformer. In addition, the winding hottest spot temperature is a function of the ambient temperature and the load profile. The transformer aging is a function of the winding hottest spot temperature. The cost-effectiveness of the transformer is based on the transformer total losses cost. Hence, TC plays a vital role in determining the loading capacity, the aging, and cost-effectiveness of the transformer. In this paper, a 630 kVA, ±5% voltage tap at the low voltage winding, ONAN cooling type, oil – immersed transformer is considered. The derivation of the impact of the TC position is based on the variation of the voltage at the medium voltage side. The winding hottest spot temperature, the aging, the energy losses, and the loading of the transformer with varying the TC positions are simulated in MATLAB programming language. The results show the TC position has a great impact on the aging, the cost-efficient, and the loading of the transformer.
2009 Elsevier Ltd. All rights reserved.
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