Modeling and simulation of transformer loading capability and hot spot temperature under harmonic conditions

Due to nonlinear loads, power frequency harmonics exist mainly in power systems so that they increase the losses and temperature inside the power transformer consequently. The hot spot temperature is one of the major limiting factors that affect the useful life of the power transformer and its loading. This paper presents the determination of field distribution on the transformer components using finite element method (FEM) and the calculations of hot spot and top oil temperature under harmonic conditions according to two techniques including dynamic thermal model and IEEE guide. The useful life of transformer is analyzed and the loading capability of transformer under harmonic conditions is furthermore verified using simulation in MATLAB.

► Harmonics in power systems can cause losses and hot spot temperature of transformers.
► We determine the field distribution on the transformer components using finite element method (FEM).
► We calculate the hot spot and top oil temperature under harmonic conditions.
► We present an algorithm to determine the loading capability of transformer under harmonic conditions.