The effect of DC bias and noise on the performances of power transformer

Direct current can be found in a transformer’s winding as a result of imperfections in connected equipment such as power electronics devices used and also due to magnetic disturbances of the earth’s field as geomagnetically induced currents (GIC). There are some host adverse effects that can potenti...

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Main Author:	Syafruddin, Hasan
Format:	Thesis
Language:	English
Subjects:	Direct current Noise Electric transformers > Design and construction Electric transformers Transformers
Online Access:	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/2/full%20text.pdf
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id	my-unimap-44114
record_format	uketd_dc
spelling	my-unimap-441142016-11-22T04:51:49Z The effect of DC bias and noise on the performances of power transformer Syafruddin, Hasan Direct current can be found in a transformer’s winding as a result of imperfections in connected equipment such as power electronics devices used and also due to magnetic disturbances of the earth’s field as geomagnetically induced currents (GIC). There are some host adverse effects that can potentially accompany the presence of direct current in a transformer’s windings, such as increased introducing extremely large voltage and current harmonic distortion, increased power losses, half-cycle saturated of the transformer core and elevated increasing of acoustic noise emission. This research involved the combination of MATLAB simulation and experimental works. Based on MATLAB program simulation, the results demonstrate that the exciting current becomes much more distort and will incline to half-circle saturation when the DC bias increases from 0.2 T to 1.0 T with the maximum saturation limit of AC magnetic flux density assumed as 2.0 T. A laboratory test is performed on lab-scale single phase power transformer. Excitation harmonics generated from dc biased and noise levels emitted by transformer core are investigated. The DC bias was injected simultaneously with AC source for no-load condition, meanwhile, through half wave rectifier with variable load for load situation. With DC bias, the transformer is prone to half-cycle saturated and rich harmonics are introduced. The simulated waveforms have good agreement with the measured one. The existence of DC bias was signified with zero and the significantly of even order harmonics beside of odd order harmonics. The harmonics contribute most to transformer noise. The higher magnetic flux density produces large harmonic and also higher noise such as 65.5, 68.4 and 72.4 dB for 1.3 T (under excited), 1.5 T (normal operation) and 1.9 T (over excited). The overall power losses and harmonics is lower for smaller core overlap length and thinner thickness of core lamination. The results of this study contribute in understanding transformers as harmonic and noise sources during DC bias existence. Universiti Malaysia Perlis (UniMAP) 2014 Thesis en http://dspace.unimap.edu.my:80/xmlui/handle/123456789/44114 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/1/p.1-24.pdf 72e27b2c50358474368ab6be823b6dd2 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/2/full%20text.pdf b3286c6c31d5c763a22ff6d403705419 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/3/license.txt 8a4605be74aa9ea9d79846c1fba20a33 Direct current Noise Electric transformers -- Design and construction Electric transformers Transformers School of Electrical Systems Engineering
institution	Universiti Malaysia Perlis
collection	UniMAP Institutional Repository
language	English
topic	Direct current Noise Electric transformers -- Design and construction Electric transformers Transformers
spellingShingle	Direct current Noise Electric transformers -- Design and construction Electric transformers Transformers Syafruddin, Hasan The effect of DC bias and noise on the performances of power transformer
description	Direct current can be found in a transformer’s winding as a result of imperfections in connected equipment such as power electronics devices used and also due to magnetic disturbances of the earth’s field as geomagnetically induced currents (GIC). There are some host adverse effects that can potentially accompany the presence of direct current in a transformer’s windings, such as increased introducing extremely large voltage and current harmonic distortion, increased power losses, half-cycle saturated of the transformer core and elevated increasing of acoustic noise emission. This research involved the combination of MATLAB simulation and experimental works. Based on MATLAB program simulation, the results demonstrate that the exciting current becomes much more distort and will incline to half-circle saturation when the DC bias increases from 0.2 T to 1.0 T with the maximum saturation limit of AC magnetic flux density assumed as 2.0 T. A laboratory test is performed on lab-scale single phase power transformer. Excitation harmonics generated from dc biased and noise levels emitted by transformer core are investigated. The DC bias was injected simultaneously with AC source for no-load condition, meanwhile, through half wave rectifier with variable load for load situation. With DC bias, the transformer is prone to half-cycle saturated and rich harmonics are introduced. The simulated waveforms have good agreement with the measured one. The existence of DC bias was signified with zero and the significantly of even order harmonics beside of odd order harmonics. The harmonics contribute most to transformer noise. The higher magnetic flux density produces large harmonic and also higher noise such as 65.5, 68.4 and 72.4 dB for 1.3 T (under excited), 1.5 T (normal operation) and 1.9 T (over excited). The overall power losses and harmonics is lower for smaller core overlap length and thinner thickness of core lamination. The results of this study contribute in understanding transformers as harmonic and noise sources during DC bias existence.
format	Thesis
author	Syafruddin, Hasan
author_facet	Syafruddin, Hasan
author_sort	Syafruddin, Hasan
title	The effect of DC bias and noise on the performances of power transformer
title_short	The effect of DC bias and noise on the performances of power transformer
title_full	The effect of DC bias and noise on the performances of power transformer
title_fullStr	The effect of DC bias and noise on the performances of power transformer
title_full_unstemmed	The effect of DC bias and noise on the performances of power transformer
title_sort	effect of dc bias and noise on the performances of power transformer
granting_institution	Universiti Malaysia Perlis (UniMAP)
granting_department	School of Electrical Systems Engineering
url	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44114/2/full%20text.pdf
_version_	1747836822472359936

The effect of DC bias and noise on the performances of power transformer

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