Thermal analysis and derating of a power transformer with harmonic loads

Hot spot as well as top oil temperatures have played the most effective parameters on the life of the electrical transformers. The prognostication of these factors is very vital for determining the residual life of the electrical transformers in the transmission and distribution systems. Thus, an accurate mathematical method is required to calculate the critical temperature such as hot spot and top oil temperature based on the different types of thermal models. In this study calculates the service life of the transformers based on an accurate top oil temperature. Accordingly, An approach solution is given for calculating the thermal model. Also, findings are validated with true temperatures. Finally, this method is implemented on 2500 KVA electrical transformer.

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“…For 𝜃 𝐻𝑆𝑇 =110 C, and per-unit-life=1, the value of A constant becomes 9.8×10-18. The aging factor can be calculated [3], [23]…”

Section: The Loss Of Life Of the Transformermentioning

confidence: 99%

Analysis of thermal models to determine the loss of life of mineral oil immersed transformers

et al. 2021

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“…Secondly, to show the developed model's validity under sinusoidal and DC-biased grid voltage cases, it is comparatively analyzed with the FEM model, which is one of the most preferred techniques for transformer analysis and design in the literature [19]. Here, it should be mentioned that the FEM modelling technique is also widely employed for the analysis of transformers under DC-biased voltage and non-linear loading conditions [20][21][22]. And then, for the considered-type transformer operated under DC bias, behaviour of the losses, excitation current's harmonic distortion, and reactive power demand are investigated with using the developed model.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of three‐phase five‐leg transformers under DC bias using a new frequency‐dependent reluctance‐based model

Canturk

Balcı

Hocaoğlu

et al. 2022

IET Generation Trans & Dist

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This paper presents a reluctance-based model considering the frequency-dependent loss nature of the windings for the analysis of three-phase five-leg transformers under grid voltages with direct current (DC) bias. This is very important especially for proper determination of their harmonic current distortion and maximum loading capability (MLC) under DC-biased grid voltage conditions. To figure out the developed model's validity under sinusoidal and DC-biased grid voltage cases, it is comparatively analyzed with the model based on 2D finite element method (FEM). Thus, for the considered transformer type operated under DC bias, the excitation current's harmonic pollution, losses, and reactive power demand parameters are analyzed by using the developed model. Additionally, by regarding these performance parameters, the DC susceptibilities of the considered-type transformer and the single-phase shell-type transformer are comparatively evaluated. Finally, for the studied grid voltage conditions, the effects of two important design considerations as (i) magnetic core material selection and (ii) legs' cross-sectional area sizing on the MLC are investigated. It is concluded from these investigations that under saturation conditions, the transformers, which have the core material with higher permeability or lower reluctance, draw higher excitation current, and have lower MLC ratio when compared to ones having the core material with lower permeability or higher reluctance. However, for unsaturated transformers, which work under DC bias, the case is the opposite to that in saturation conditions. On the other hand, under DC bias conditions, the effect of cross-sectional area sizing on the MLC ratio is much more for the transformer with high permeable magnetic core material with regards to ones with low permeable magnetic core material.

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“…In the transition region, the current-carrying connections defects often appear due to metal wear during production and operation or longterm aging, which will cause the overheating and failure of the valve-side bushing as shown in Figure 1. Therefore, it is very important to detect the defects and evaluate the state of the copper-aluminium transition region in the valve-side bushing [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

3‐D thermal analysis for the valve‐side bushings of HVDC converter transformer and application in the evaluation of current‐carrying connections defects

Miao

Wu³

et al. 2022

IET Generation Trans & Dist

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To analyze the overheating problem of the valve‐side bushings of high voltage direct current (HVDC) converter transformer, which is mainly caused by current‐carrying connections defects at copper–aluminium transition region in the bushing, this paper set up a 3‐D electromagnetic‐thermal analysis model for the valve‐side bushings, and a method was proposed to calculate the thermal distribution of the valve‐side bushings under the influence of current‐carrying connections defects. Based on this model, the details of an example were shown in this paper, and the numerical results agreed with the measured results within 1%. Then, the temperature field distribution characteristics of valve‐side bushing under different working current I, defect degree k, and ambient temperature Tamb were determined. According to the characteristics, the temperature difference ΔT and working current I of the bushing were applied to evaluate contact resistance at the copper–aluminium transition region of the bushing, which can be provided by a novel method to evaluate for current‐carrying connections defects in the valve‐side bushings.

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Thermal analysis and derating of a power transformer with harmonic loads

Cited by 25 publications

References 29 publications

Analysis of thermal models to determine the loss of life of mineral oil immersed transformers

Analysis of thermal models to determine the loss of life of mineral oil immersed transformers

Performance analysis of three‐phase five‐leg transformers under DC bias using a new frequency‐dependent reluctance‐based model

3‐D thermal analysis for the valve‐side bushings of HVDC converter transformer and application in the evaluation of current‐carrying connections defects

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