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A comparative analysis applied to identification of partial discharges in dry-type transformers by inductive sensors and acoustic emission

Grant number: 20/11035-3
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): November 01, 2020
Effective date (End): April 30, 2021
Field of knowledge:Engineering - Electrical Engineering
Principal researcher:Bruno Albuquerque de Castro
Grantee:Vitor Vecina dos Santos
Home Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

The interest in monitoring systems applied to power transformers has grown significantly in recent years and the motivation for the study comes from industry and academy sectors. Among several existing topologies, dry-type transformers have an important role in the electrical systems and industry. In this device, air circulation performs heat exchange and the insulation is composed by materials such as paper and epoxy resin. Some critical issues in the operation of the transformer can induce a slow degradation of the insulation materials, leading it to total failure. In the stages before the total failure, it is common to detect discharges in the insulation of the electrical machine. Among several methodologies to monitor discharges in transformers, acoustic emission (AE) and current analysis (CA) are characterized as promising non-destructive approach. In AE, piezoelectric transducers capture the acoustic waves emitted by the discharges. In CA, the electric current signature is analysed by using inductive sensors to identify the transients generated the failures. The objective of this work is to apply the discrete Fourier transform (DFT) and the Wavelet transform (WT) in the current and acoustic emission signals aiming to differentiate discharges in paper insulation and epoxy resins. In practice, each material requires different maintenance actions, and therefore, the differentiation of the types of failures is crucial to the improvement of this research field. In fact, besides to the scientific contribution of the proposal, this work has an international cooperation with the research group of the High Voltage Laboratory at the Technical University Federico de Santa Maria, in Santiago, Chile.