Improvement of distribution transformer fault analysis using FRA method
The distribution transformers are one of the most expensive components in the electrical power distribution system. During its lifetime, distribution transformers are exposed to several failures. For this reason, it is crucial to continuously monitor its condition. Frequency Response Analysis (...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/942/1/24p%20SALEM%20MGAMMAL%20AWADH%20NASSER%20AL-AMERI.pdf http://eprints.uthm.edu.my/942/2/SALEM%20MGAMMAL%20AWADH%20NASSER%20AL-AMERI%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/942/3/SALEM%20MGAMMAL%20AWADH%20NASSER%20AL-AMERI%20WATERMARK.pdf |
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| Summary: | The distribution transformers are one of the most expensive components in the
electrical power distribution system. During its lifetime, distribution transformers are
exposed to several failures. For this reason, it is crucial to continuously monitor its
condition. Frequency Response Analysis (FRA) is an advanced electrical test, which
is commonly employed to investigate the transformer’s main winding. Moreover, it
has been shown to be sensitive to non-mechanical changes such as winding
insulation. The measured FRA result needs to be compared with the previous
measurement to identify any variation between them. The variation will indicate
mechanical changes in the transformer. However, interpreting the variation to
determine the type, location, and severity of the suspected failure, requires expertise.
For this reason, further understanding of the damage detecting characteristic of FRA
is required. In this study, an electrical circuit model is developed based on 33/11kV,
1MVA distribution transformer to investigate the influence of various changes in the
winding RLC values on the frequency response. The model is also used to simulate
other failures such as winding deformation, bushing and short circuit faults. In
addition, the tap changer fault and weakness of clamping structure are also
investigated by examining an 11/0.433 kV, 500KVA distribution transformer.
Additionally, the transformer ageing and degradation of winding’s insulation is also
investigated using different FRA measurement configuration. Findings show that tap
changer coking and clamping faults affect the frequency response at less than 2kHz.
FRA capacitive inter-winding shows isolation in between 2kHz to 20kHz due to
transformer ageing. The frequency response shifting towards lower frequencies at
20kHz to 2MHz due to winding insulation degradation. Also, in this study, the
method or interpretation scheme for FRA is obtained. It is a guideline in the form of
a flowchart, which is proposed for the first time and helps the engineers in having a
better interpretation of FRA results. In conclusion, this study is to improve the
understanding on the distribution transformers faults detection using FRA method. |
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