Abstract
Hot spot temperature (HST) is an important parameter reflecting the working state of the traction transformer, and the load characteristics have a great influence on the HST. The current researches rarely consider the load characteristics of transformers in-depth, and most of the research on the temperature field focuses on steady load. Therefore, a prediction model of HST for the traction transformer considering the load characteristics is established by the finite element simulation in this paper. Considering the impact and nonlinearity of traction load, the influence of the load characteristics on the HST is studied. Analysis of the load curve revealed that the steady and step load combination could well simulate the traction load. Based on the analysis of traction transformer load characteristics, the temperature field coupling calculation of traction transformer is carried out according to the VI normative duty class. On this basis, the influence of load rate and time on HST is studied. The present findings show that the method can predict the HST of traction transformer under different working conditions and provide a reference for load dispatching of traction transformer. The simulation data are in good agreement with the test results, and the average relative error is 3.4%. The results verify the effectiveness of the proposed method.
Highlights
As an essential part of urban rail transit, the traction transformer operation’s reliability depends on its insulation performance [1], [2]
10−3 where, PT is the total loss of the traction transformer, PNL is no-load loss, PLL is load loss, Phl is magnetic hysteresis loss, Pcl is eddy-current loss, η is the hysteresis factor of the iron core, f is the power supply frequency, Bmax is the maximum flux density, V is the volume of the iron core, d is the thickness of silicon steel sheet
2) LOSS ANALYSIS UNDER STEP LOAD In practical application, it is not easy to calculate with an accurate load curve
Summary
As an essential part of urban rail transit, the traction transformer operation’s reliability depends on its insulation performance [1], [2]. The traction transformer’s insulation performance is closely related to the heat generation and heat dissipation inside the traction transformer [3], [4]. The traction transformer’s operation instability or damage is mainly due to the temperature of the transformer windings. The accurate prediction of HST for traction transformer is of great significance to improve the traction transformer operation’s reliability and ensure the train’s stable operation [5], [6]. Insulation aging is closely related to the internal temperature field of the transformer.
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