Automatic selection of frequency bands for the power ratios separation technique in partial discharge measurements: part I, fundamentals and noise rejection in simple test objects

Partial discharge (PD) measurements are important for the monitoring of the status of almost any type of high-voltage equipment. The use of this technique for on-line measurements involves several challenges related to noise rejection and PD source recognition. In order to face these issues, pulse shape analyses are made in high-frequency and very-high-frequency ranges. The authors proposed in a previous paper the so-called Power Ratios (PR) of the spectra as useful parameters for pulse source separation in a two-dimensional approach. This technique provides good results, but its reliability depends on the appropriate selection of two frequency intervals where these spectral power ratios are calculated. In order to improve this separation system, the authors propose an algorithm that provides the frequency intervals necessary to obtain very good separation results in several experimental setups. The explanation of the system and the results obtained are presented in two papers. The simultaneous measurements of pulse sources (PD or noise) are complemented with pulse characterization when only one single source is active in order to check that the selected frequency intervals are appropriate. In this first paper, the authors summarize the fundamentals of the proposed algorithm and its first results for PD and noise separation in simple test objects that create corona, internal and surface discharges.