Abstract
It has been over two decades since the publication of pioneer works about the power transformer diagnostics based on monitoring of their acoustic fingerprints. Since then, there has been great progress in this field and the methods used are as complex as ever. Any unnecessary intervention on a power transformer implies its temporary disconnection from the power grid. The inability to supply electricity to the customer means not only financial loss for the utility but also generates a non-material loss, e.g., the loss of reputation to the customer. Faster, more accurate, more reliable, and less invasive diagnosis is the main reason behind development and improvement in this field. The main goal of this paper is to categorize and review state-of-the art of vibro-acoustic diagnostic methods for power transformers. This paper opens with a brief note about continuous condition monitoring, after which we overview the causes of transformer vibrations as well as the collection and preprocessing of diagnostic data. Then, we review and categorize works related to the acoustic condition assessment of power transformers considering both: feature extraction in the time, frequency, time-frequency domain, and mathematical modeling and system identification of dynamic systems.
Highlights
Preventive maintenance of machinery and other objects is becoming more and more suppressed by continuous monitoring
Rest of the paper is structured as follows: in section II a brief overview of causes behind transformer vibrations is given; in section III, diagnostic data collection and preprocessing are discussed; sections IV and V are the focus of the work and here the literature on vibro-acoustic methods for condition assessment of power transformers is surveyed
High complexity and nonlinearity is observed in the results shown in numerous papers dealing with on-load tap changer (OLTC) diagnostics
Summary
Preventive maintenance of machinery and other objects is becoming more and more suppressed by continuous monitoring. Some newer compiled failure statistics [4] (transformer failure data from 22 countries) show progress in the reliability of the OLTC (27%), but there is still a high percentage of failures connected to windings (40%) and core (3.4%) (see Fig. 1) This is precisely the reason why this paper focuses on vibro-acoustic diagnostic methods for these three parts of the transformer. Rest of the paper is structured as follows: in section II a brief overview of causes behind transformer vibrations is given; in section III, diagnostic data collection and preprocessing are discussed; sections IV and V are the focus of the work and here the literature on vibro-acoustic methods for condition assessment of power transformers is surveyed.
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