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Under harmonic conditions, caused by nonlinear loads, losses and temperature inside the power transformer increase. The hot spot temperature is one of the major limiting factors that affect the transformer life time and its loading capability considerably. This paper presents the determination of field distribution on the transformer components as well as its losses using finite element method (FEM). The hot spot and top oil temperature are computed under harmonic conditions according to two techniques, i.e. the dynamic thermal model and IEEE guide. The effect of harmonics on the useful life of transformer is then analyzed. Finally, an algorithm is proposed to determine the loading capability of transformer under harmonic conditions. [ABSTRACT FROM PUBLISHER]

This paper presents a model of lightning performance of a 400kV double circuit overhead transmission line using ATP/EMTP. Including the models of transmission line, tower surge response, footing impedance, impulse electric strength of line insulator and lightning stroke as well as corona, the paper introduces a comprehensive lightning transients study. Based on this model, the paper discussed the influence of corona on two transient phenomena known as back flashover and shielding failure. [ABSTRACT FROM PUBLISHER]