Application of Acoustic Emission and Thermal Imaging to Test Oil Power Transformers

Franciszek Witos,Grzegorz Szerszeń,Zbigniew Opilski,Aneta Olszewska,Agnieszka Lisowska-Lis

doi:10.3390/en13225955

Franciszek Witos, Grzegorz Szerszeń + Show 3 more

Open Access

https://doi.org/10.3390/en13225955

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Abstract

In this paper, the research methodology and the results of the analysis carried out using the acoustic emission (AE) and thermal imaging for a selected oil power transformer are presented. The basis for the research, by means of the AE method, was the author’s patented research method. The AE descriptor maps on the side walls of the tested transformer along with the location of areas with increased AE activity and an analysis of the properties of AE signals recorded at the measurement points located in these areas have been performed. The results showed no partial discharges that could threaten further operation of the tested transformer as well as three areas where increased magnetoacoustic emission occurred. Thermal imaging studies were carried out in the 7.5 μm < λ < 13 μm band. Three areas were located on the calculated thermograms: the entire upper surface of the transformer tank and two areas on the side walls of the tested transformer in which increased IR radiation occurred. The results of the analysis of the research results for the two methods correspond with each other, having a common part, and complement each other giving a broader description of studied phenomena.

Highlights

Oil power transformers are an important element of the power system, and detailed rules of their operation and operational research programs are developed to avoid failures [1,2].Operational testing programs for oil power transformers aimed at avoiding transformer failure include basic, specialist, and periodic tests
In the area of specialist and periodic tests, an important role is played by tests performed without disconnecting the transformer from the network. These are chromatographic analysis of gases dissolved in transformer oil (DGA), tests of the content of furan compounds dissolved in oil, tests of partial discharges (PDs) by electrical, acoustic, chemical, and optical methods, tests of magnetization processes occurring in the magnetic circuit of a transformer, vibroacoustic analysis, and thermal imaging studies
They are: (a) acoustic emission (AE) signals generated during deformation processes [11,20] that accompany partial discharges (PDs) [8,35,36], magnetoacoustic emission (MAE) signals generated by numerous phenomena that occur during the magnetization of the ferromagnetic materials [13,14], acoustic signals generated during oil circulation in the transformer, vibroacoustic signals, and outer acoustic interference

Summary

Introduction

Oil power transformers are an important element of the power system, and detailed rules of their operation and operational research programs are developed to avoid failures [1,2].Operational testing programs for oil power transformers aimed at avoiding transformer failure include basic, specialist, and periodic tests. In the area of specialist and periodic tests, an important role is played by tests performed without disconnecting the transformer from the network These are chromatographic analysis of gases dissolved in transformer oil (DGA), tests of the content of furan compounds dissolved in oil, tests of partial discharges (PDs) by electrical, acoustic, chemical, and optical methods, tests of magnetization processes occurring in the magnetic circuit of a transformer, vibroacoustic analysis, and thermal imaging studies. Complete discharges, overheating, damage to the tap switch, and contaminants in the oil (such as sulfur or fine particles) Since these processes deteriorate the insulation condition and shorten the transformer’s lifetime, the following parameters of the transformers are constantly monitored: the temperature of the core, the temperature of the windings and the oil temperature, the oil humidity, the gases dissolved in the oil (for example, hydrogen, acetylene, other explosive gases, carbon dioxide, and carbon monoxide). A quick detection of overheating is necessary, for example through the use of thermography [33,42]

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