Estimation of de-trapped charge for diagnosis of transformer insulation using short-duration polarisation current employing detrended fluctuation analysis

• Published in: High voltage Vol. 5; no. 5; pp. 636 - 641
• Main Authors: Dutta, Saurabh, Mishra, Deepak, Baral, Arijit, Chakravorti, Sivaji
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 01.10.2020; Wiley
• Subjects: charge carriers; charge measurement; detrended fluctuation analysis-based technique; electric current measurement; fluctuations; normalised detrapped charge; off-line time-consuming process; oil-paper interface; PDC data; polarisation; polarisation-depolarisation currents; power transformer insulation; real-life power transformers; Research Article; short-duration polarisation current; transformer oil; oil-paper interface; polarisation; real-life power transformers; normalised detrapped charge; charge measurement; detrended fluctuation analysis-based technique; off-line time-consuming process; paper; fluctuations; charge carriers; PDC data; transformer oil; electric current measurement; power transformer insulation; short-duration polarisation current; polarisation-depolarisation currents
• ISSN: 2397-7264; 2397-7264
• DOI: 10.1049/hve.2019.0348

Researchers have shown that the value of charge carriers, de-trapped from the oil–paper interface of power transformer insulation, is useful in carrying out the diagnosis. However, the evaluation of the de-trapped charge requires the analysis of polarisation–depolarisation currents. Being an off-line time-consuming process, the measurement and analysis of polarisation and depolarisation current (PDC) data are not practically advantageous. The study presents a detrended fluctuation analysis-based technique to estimate the magnitude of normalised de-trapped charge using the polarisation current measured for a short duration. Using the proposed technique, the requirement of measuring the complete PDC data, for diagnosis purposes, can be eliminated. Further, the technique also eliminates the requirement of depolarisation current which in turn facilitates a reduction in equipment shutdown time. The applicability of the proposed technique is tested on the data obtained from several real-life power transformers.