The Use of Generalized Gaussian Distribution in Vibroacoustic Detection of Power Transformer Core Damage

Vibroacoustic diagnostics (VM-Vibroacoustic Method) is one of the methods for diagnosing the active part of power transformers. Measurement technologies have been refined over the past several years, but the methods of analyzing data obtained in VM diagnostics are still in development. In most cases, they are based on a simple frequency spectrum analysis, and the diagnostic conclusions are subjective and depend on the expert's professional experience. The article presents an objective method for the detection of transformer unit core damage, based on the analysis of the statistical properties of the vibration signal registered on the surface of the tank of an unloaded transformer in the steady state of vibrations (VM). The algorithm for proceeding further is: FFT analysis of the vibroacoustic signal, with the determination of the relative changes in vibration power as a function of frequency <mml:semantics>Pr(f)</mml:semantics> and, finally, the determination of the statistic properties of the dataset <mml:semantics>Pr(f)</mml:semantics>. The Generalized Gaussian Distribution (GGD) is used to describe the <mml:semantics>Pr(f)</mml:semantics> set. The detector output values are the <mml:semantics>lambda</mml:semantics> and p parameters of the GGD distribution. These two numerical values form the basis for the classification of the technical condition of the transformer unit core. The correctness of the described solution was verified on the example of ten pieces of 16 MVA power transformers with different operating times and degrees of wear.