A Simple Model for Calculating Transformer Hot-Spot Temperature

Energy Res. Dept., SINTEF, Trondheim
IEEE Transactions on Power Delivery (Impact Factor: 1.73). 08/2009; 24(3):1257 - 1265. DOI: 10.1109/TPWRD.2009.2022670
Source: IEEE Xplore


A simple model for calculating the hot-spot temperature is introduced. The model is based on the hot-spot to ambient gradient. The model considers the changes of the oil viscosity and winding losses with temperature. The results are compared with temperatures calculated by IEEE Annex G method and measured results at varying load for the following transformer units: 250-MVA ONAF, 400-MVA ONAF, and 605-MVA OFAF.

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    • "At moments of loading jerks, the calculation of temperature h due to the proposed model gives the most accurate values as compared to the known methods. The results obtained correspond to the results published by foreign authors[5,6]wherefore they may be recognized to be satisfactory. "
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    ABSTRACT: It has been proven that the introduction of the systems for continuous control of the power transformer technical state predetermines the need for improvement of the methods for calculation of the thermal modes, insulation wear and remaining service life of the equipment. Disadvantages of the existing methods recommended by domestic and foreign regulatory documents are noted. It is appeared to be practically to consider parameters of the environment, thermal mode retention and non-linearity of the thermal characteristics. The structure of algorithm for calculating temperature charts according to the load parameters with regard to the influence of the above factors is proposed. The developed software is briefly specified, too. The ultimate purpose is to develop and study the improved model for thermal characteristic calculation designed for the systems of on-line monitoring transformer technical state.
    Full-text · Article · Dec 2015 · Procedia Engineering
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    • "IEEE guide [9], [18] and IEC 60354 loading guide for oil-immersed power transformers [16]. In [5], [13], and [17], Swift et al. proposed a basic approach of modelling based on heat transfer theory. The existing models are studied below. "
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    ABSTRACT: Integration of rooftop photovoltaics (PVs) in residential networks at moderate penetration levels is becoming a reality in many countries including Australia. Despite the technical challenges in properly accommodating PV units, one of the major benefits is the ability of PV units to extend useful life time of distribution transformers. This effect is not quantified in the existing literature. This paper carries out an analysis into the impacts of rooftop PVs at different penetration levels on the performance of distribution transformers and residential networks. This paper presents a methodology to quantify the benefit of the distribution transformer life extension brought about by customer-owned rooftop PV units. The proposed methodology is applied to a real distribution system with various scenarios, including different penetration levels. The results show the distribution transformer loss-of-life function, as a function of the rooftop PV penetration level, is monotonically decreasing function which saturates after a certain penetration level. The best life improvements occur with transformers that are highly loaded and the presence of a significant PV installation may support the deferral of transformer upgrades.
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    ABSTRACT: Thermal stresses are the main factor of deterioration of transformer insulation. These stresses, which are originated from heavy loading, are more severe in the hot spot of transformer winding. So, the transformer loading capability is mainly restricted by the hot spot temperature. In this paper, a new method is proposed for transformer dynamic loading capability assessment using fuzzy modeling. Firstly, the hot spot temperature is estimated by fuzzy thermal model and then is compared with the temperatures obtained by measurement and IEEE thermal model. Afterwards, the method of dynamic loadability assessment is described and implemented by the fuzzy model. Comparison between the results obtained by the fuzzy thermal model and the IEEE model demonstrates the usefulness of the fuzzy model application. Also, this fact is emphasized by an economic analysis.
    No preview · Article · Jun 2009 · International Review of Electrical Engineering
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