Towards Online Ageing Detection in Transformer Oil: A Review

Abstract

Transformers play an essential role in power networks, ensuring that generated power gets to consumers at the safest voltage level. However, they are prone to insulation failure from ageing, which has fatal and economic consequences if left undetected or unattended. Traditional detection methods are based on scheduled maintenance practices that often involve taking samples from in situ transformers and analysing them in laboratories using several techniques. This conventional method exposes the engineer performing the test to hazards, requires specialised training, and does not guarantee reliable results because samples can be contaminated during collection and transportation. This paper reviews the transformer oil types and some traditional ageing detection methods, including breakdown voltage (BDV), spectroscopy, dissolved gas analysis, total acid number, interfacial tension, and corresponding regulating standards. In addition, a review of sensors, technologies to improve the reliability of online ageing detection, and related online transformer ageing systems is covered in this work. A non-destructive online ageing detection method for in situ transformer oil is a better alternative to the traditional offline detection method. Moreover, when combined with the Internet of Things (IoT) and artificial intelligence, a prescriptive maintenance solution emerges, offering more advantages and robustness than offline preventive maintenance approaches.

A new technique for fault diagnosis in transformer insulating oil based on infrared spectroscopy measurements

“…In fact, as the amounts of these byproducts increase within the oil insulation, the power loss (DDF) increases. Generally, the DDF value can be taken as an indication of the by-product quantities formed in each oil sample [48,49]. Anyway, it is clear from Figure 11a that the insulating material seems to be stable throughout the whole range even after the electrical fault.…”

Adsorption Behavior of Dissolved Gas Molecules in Transformer Oil on Rh Modified GeSe Monolayer

“…As one of the main equipment in the power system, the normal operation of the transformer is crucial for the reliability and stability of the power system . Dissolved gas analysis (DGA) in oil is an effective means to find early transformer faults and can determine the operating status of the transformer in advance, , which is of great significance in guiding the transformer overhaul work and preventing major accidents in the power grid. − Overheating of oil and paper inside the transformer, partial discharge of oil-paper insulation, moisture or bubbles in the oil, increased water content in the oil, and so forth will produce H 2 , CH 4 , NO 2 , C 2 H 2 , CH 4 , and other dissolved gases in the oil. − DGA can monitor the dissolved gas in the transformer oil in real time and online and send out an alarm signal when the concentration and rate of change of the dissolved gas in the oil exceeds a certain limit, so that effective measures can be taken in time to avoid transformer failure. , Therefore, the effective monitoring of dissolved gases in transformer oils is of great significance.…”

“…8−10 DGA can monitor the dissolved gas in the transformer oil in real time and online and send out an alarm signal when the concentration and rate of change of the dissolved gas in the oil exceeds a certain limit, so that effective measures can be taken in time to avoid transformer failure. 11,12 Therefore, the effective monitoring of dissolved gases in transformer oils is of great significance.…”

Transformer Oil Temperature Variation Based on Terahertz Time-domain Spectroscopy

“…The main research object is to study and analyze the biodiesel content in the mixture of petroleum diesel engines by THz-TDS, and obtain the absorption characteristics of the above-mentioned oils in the terahertz band [5] . In the process of transformer insulation oil detection, domestic and foreign scholars have also conducted in-depth research [6][7] .…”