Abstract
The transformer bushing hot spot temperature (HST) seriously affects its performance and design. In this paper, a novel method for calculating the hot spot temperature of bushing is proposed, in which the principle of constant joule heat is adopted to transform the fluctuating current into the steady-state current. Firstly, the fluctuating current based on time is segmented. Then, the fluctuating current in each period of time is transformed into steady-state current which is used as heat source. Next, the Finite Element Method (FEM) is used to determine a typical bushing's temperature distribution and specify its hot spot. According to the calculation results of hot spot temperature rise, the time interval is adjusted. Finally, the optimal time interval and the steady-state equivalent current are obtained by solving the hot spot temperature of the transformer bushing iteratively. In addition, the method is used to calculate the hot spot temperature of a 220kV Oil Impregnated Paper (OIP) bushing. Compared with the results of traditional transient calculation method, the validity of the proposed method is verified, and the computing time is greatly reduced.
Highlights
Bushings are essential component of power transformers
GOVERNING EQUATION OF TRANSIENT TEMPERATURE FIELD 1) HEAT SOURCE OF TRANSFORMER BUSHING The heat source of transformer bushing mainly comes from two aspects [8] : 1) The joule heat generated by the current passing through the conductor is shown in the following equation
The time-harmonic electric field of bushing is calculated by the finite element method, and the internal dielectric loss is obtained
Summary
Bushings are essential component of power transformers. Without bushings, large power transformers are unthinkable. Z. Yang et al.: Calculation of HST of Transformer Bushing Considering Current Fluctuation model to calculate the transient temperature distribution of the transformer bushing. Allahbakhshi and Akbari [8] calculated the temperature field distribution of a two-dimensional axisymmetric model of a typical OIP bushing using FEM and COMSOL, and studied the position of hot spots under different load. AkbariM et al [2] used FEM to calculate the transient temperature field of the 110 kV transformer bushing. GOVERNING EQUATION OF TRANSIENT TEMPERATURE FIELD 1) HEAT SOURCE OF TRANSFORMER BUSHING The heat source of transformer bushing mainly comes from two aspects [8] : 1) The joule heat generated by the current passing through the conductor is shown in the following equation.
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