Vibro-Acoustic Methods in the Condition Assessment of Power Transformers: A Survey

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.

Transformer Condition Monitoring Based on Load-Varied Vibration Response and GRU Neural Networks

“…In the FE model, the hysteresis phenomenon is ignored, and the mean value is used instead. The electromagnetic force distribution can be obtained by establishing a 2-D axisymmetric model in ANSYS [9]. The axial electromagnetic force amplitude defined in (2) is obtained when the input current is 75 A, which is shown in Fig.…”

“…Increased concerns about fault detection and diagnosis efficiency in a smart-grid context have motivated research into developing online non-intrusive monitoring techniques [5]. Previous studies have shown that transformer vibration is connected with the mechanical properties of windings, and the vibration technique has been used to provide diagnostic information [6][7][8][9].…”

Load Noise Prediction of High-Voltage Transformers by Equation Applying 3-D EMCN

“…The SPL can be expressed as (4), where Prms is the rootmean-square (RMS) value of the sound pressure and Pref Thus, it is important to investigate the relationship between the sound pressure and Lorentz force generated by the windings to predict the load noise of a 3-phase transformer.…”

“…There are several kinds of transformer noise; load noise, caused by the electromagnetic force generated by the interaction between electric and magnetic fields; core noise, produced by magnetostriction of the laminated core; cooling noise, generated by the cooling components of transformers such as cooling fans. Among these noise sources, load noise becomes the dominant source of total transformer noise with an increase in the transformer power [2]- [4].…”

“…By using equations (5)-(10), the initial equation for the sound pressure is shown as(11). The initial form of the load noise prediction equation is obtained by(12) by applying(11) to(4).…”