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A New Technique To Detect Loss Of Insulation Life In Power Transformers

Abu Bakar, Norazhar (2016) A New Technique To Detect Loss Of Insulation Life In Power Transformers. PhD thesis, Universiti Teknikal Malaysia Melaka.

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Power transformer condition monitoring plays an important role in order to maintain the reliability of power systems operations. Failure of a power transformer could lead to a major disaster affecting the whole transmission and distribution network systems. The quality of the insulation system within power transformers comprising dielectric insulation paper and oil reflects the overall health condition of the transformer. The combination of heat (pyrolysis), moisture (hydrolysis) and air (oxidation) within operating transformers causes oil and paper decomposition which result in a number of gases that relate to the cause and effect of various faults. A gas chromatography (GC) instrument is currently used as a laboratory-based technique to quantify dissolved gases in transformer oil samples. However, the GC technique incurs running costs and requires an expert to conduct the test. Furthermore, due to the complexity of the equipment, GC measurement can only performed in a laboratory environment hence takes a long time to get the results. On the other hand, the quality of the insulating oil influences the performance and the service life of the transformer. During the oil aging process, oil gets contaminated with dissolved decay products and sludge as a result of the chemical reaction between the mineral oil molecules and oxygen dissolved in oil. Sludge and contamination development in insulating oil can be identified by measuring the interfacial tension (IFT) value of the oil. The ASTM D971 standard (Interfacial Tension of Oil Against Water by the Ring Method) is widely used to measure IFT of insulating oil. However, this technique is very sensitive and if the precautions mentioned in the standard procedure are not carefully followed may result in an incorrect or inconsistent IFT reading. Moreover, the current technique calls for a trained person to conduct the test that requires a relatively expensive piece of equipment and lengthy time to get the results as oil samples have to be sent to an external laboratory which also incurs an additional running cost. This thesis proposes an alternative method of measuring the IFT and dissolved gases in transformer oil using absorption spectroscopy which can be performed instantly on-site and has the potential to be implemented on-line. Two novel methods were developed: measuring transformer oil IFT using ultraviolet-to-visible (UV-Vis) spectroscopy, and detecting dissolved gases in transformer oil using near-infrared-to-infrared (NIR-IR) spectroscopy. Also, a new fuzzy logic approach to provide a proper asset management decision and predict the remaining operational life of a power transformer based on some routine insulating oil tests such as furan, dissolved gas analysis (DGA), IFT, water content, and operating temperature has been proposed in this thesis.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Finite element method, Electric inverters, Electric transformers -- Design and construction, Electric power transmission, Electric inductors
Subjects: T Technology > T Technology (General)
T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Library > Tesis > FKEKK
Depositing User: NOR AINI MD.JALI
Date Deposited: 31 Jul 2017 00:57
Last Modified: 31 Jul 2017 00:57

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