On Savitzky–Golay Filtering for Online Condition Monitoring of Transformer On-Load Tap Changer

Abstract

Abstract-Vibro-acoustic measurement on a transformer's On-Load Tap Changer (OLTC) can provide indications on its mechanical condition. Recently, a joint vibro-acoustic and arcing measurement system has been proposed, which can correlate the vibro-acoustic signal to mechanical events of OLTC's operation. However, there are still considerable difficulties in extracting useful information from both vibro-acoustic signal and arcing signal in a synchronized manner without any distortions in the extracted signals. In this paper, Savitzky-Golay filter is introduced to process the signals acquired from a joint vibro-acoustic and arcing measurement system installed on in-service OLTCs. It proves that the Savitzky-Golay filter can process both vibroacoustic and arcing signals induced by OLTC, extract essential information without any time delay from both types of signals, and retrieve voltage phase information from the arcing signal. The methodologies developed in this paper can improve the visibility of OLTC's mechanical operation for an effective online condition monitoring.

Improving the frequency response of Savitzky-Golay filters via colored-noise models

“…For a fixed polynomial degree, the side-lobes and variance of an FIR SGfilter are lowered by increasing the filter order; however, this also decreases the bandwidth [10]. This inflexibility of standard SG-filters is evident in a number of applications where polynomials of high degree are necessary to achieve the desired bandwidth in low-variance designs [4], [8], [10]. It is recommended here that the polynomial degree should be matched to the known characteristics of the signal and not used as a means of setting the filter bandwidth or side-lobe height.…”

“…dilute, distant, or covert), and the environment cluttered, additional processing/filtering is necessary to ensure satisfactory performance. Digital linear-phase finite-impulse-response (FIR) realizations of polynomial regression filters, sometimes known as Savitzky-Golay (SG) filters (named after the physical chemists who first applied them to the smoothing of spectra), are commonly used in such problems; for instance in: image-processing [1], [2], power-engineering [3], [4], and bio-medical applications [5], [6], [7], [8], [9]. SG-filters are popular and have a long history because they have: a low computational complexity, for fast realization in online systems; and a simple mathematical foundation, for the intuitive interpretation of their operation and output.…”

A Review of Fault Diagnosis Research on On-Load Tap-Changers

“…As an important voltage regulating equipment in the power system, the on-load tap-changer can automatically change the taps, adjust the transformation ratio, adjust the voltage and reduce the loss during the system operation, so it has been widely used. Through investigation and statistics of OLTC failure modes, it is found that transformer failures caused by OLTC irregular operation account for more than 27% of the total number of transformer accidents, which is the main reason for transformer failure [1][2][3] . This article will summarize the research methods of OLTC fault diagnosis, and put forward the remaining problems and analysis of the links that can be broken.…”

Dynamic Finite Element Model Updating for On-load Tap Changer based on Super-model

“…Seo et al [5] present the set-up of OLTC vibration measurement system, and based on test data, base waveform determination and waveform alignment methods are proposed for comparing waveforms of different tap positions. In addition, they introduce savitzky-Golay filter to process the signals acquired from a joint vibroacoustic and arcing measurement system [6]. This method can improve the visibility of OLTC's mechanical operation for an effective online condition monitoring.…”