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Power companies arrange regular training sessions to keep their operators ready to face blackout events, and expert systems play an important role in achieving this goal. Expert systems [1] have been proven to be an effective platform for diagnostic and control applications in power industry. Conventional expert systems are PC based and are not of much use where the expertise is required over a large...
The international trend is for power utilities having major capital equipment with service ages in excess of their assigned lifetimes. The key role for the asset manager in this situation is to be able to define the risks for future operation. This will then permit criticality based decisions for managing future operating and capital expenditure. The first step is to define relevant failure modes...
Experience in on-line UHF partial discharge detection on high voltage plug-in cable connectors (terminations) for GIS and transformers are presented. Narrow vs. broadband, as well as zero-span measurements were carried out using a spectrum analyzer on a laboratory setup with a built-in artificial PD defect of variable intensity. A sensitivity below 5 pC turned out to be detectable by the presented...
Fifteen years since the first application of the UHF method for partial discharge in gas insulated switchgear, this has become widely used and the preferred method for PD diagnostics in GIS. Same technique is currently starting to be applied for onsite PD testing of Power Transformers. Significant advantages of this UHF method include the reduction of background noise and the possibility of on-line...
In this paper, in order to represent three kinds of typical partial discharge respectively happened in dielectric, out of dielectric and surface of dielectric, five kinds of typical partial discharge models, which included needle to plate, needle to needle, plate to plate, surface and air void, were designed and manufactured with aluminum. Based on the designed models, an experiment system of ultra...
Transformer fault diagnosis based on artificial neural networks (ANN) is widely used, because ANN has essential nonlinear character, parallel processing ability and the ability of self organize and self learning. But there exist problems if we use traditional ANN method alone to diagnose transformer fault, the large input vector dimension and complex training database will cause the computation complexity...
A method based on frequency characteristics to distinguish partial discharge (PD) source in oil filled transformer is proposed. Frequency spectrum of electromagnetic wave from two typical PD sources, i.e., protrusion of metal and air void in oil was investigated. It was found that metal protrusion gave PD signal with stronger component in the frequency range above several hundreds MHz compared with...
Modern T&D system has the issues about economical aspects, aged equipment, reliability etc. To solve these issues, equipment should be maintained optimally and the T&D system should be operated based on the present performance of equipment. For realization of these purposes, intelligent grid management system (IGMS) was proposed and its basic functions are being investigated. In this paper,...
Notice of Violation of IEEE Publication Principles"New Distribution Class Arrester Ground Lead Disconnector Design,"by Yong-Sung Choi; Ju-Ho Yun; Hyang-Kon Kim; Chung-Seog Choi; Kyung-Sup Lee,in the Proceedings of the 2008 International Conference on Condition Monitoring and Diagnosis, 21-24 April 2008, pp 731-734After careful and considered review of the content and authorship of this paper...
This paper proposes a partial discharge analysis in cylindrical insulators model for finding electrical parameters. There are three types of electric insulator, namely liquid, solid and gas insulator. The capacitance, dielectric loss factor (tandelta) are found by measuring PD pattern of each insulator. The power dielectric loss (Pd) of each electric insulator also calculates by using the result of...
Frequency response analysis (FRA) is a diagnosis method to detect troubles of a transformer, which are deformation and displacement of winging and so, by detecting change of a transfer function compared with that measured when the transformer is normal. However, identification of the troubles detected by FRA is not clear. In this paper, firstly, identification method of the troubles is investigated...
Sweep frequency response analyzer (SFRA) measurements are now an established method for condition assessment of power transformers. Since most of evaluation procedures is based on comparison between; 1) earlier measurements on same transformer, 2) measurements on sister transformers, or 3) phase to phase comparison on same transformer, the measurement accuracy and repeatability is of utmost importance...
The practical interest of power utilities regarding the maintenance and replacement policy of insulating systems such as cables, switchgear and transformers is often based on experiences knowledge and data from the past. The ages of components in the network are increasing and this can result in an increase of the number of failures in coming years. To be able to monitor the components powerful tools...
PD measurement is well-known method for inspection of high voltage equipment. However, its on-site application has some difficulties. This paper is dedicated to the calibration of PD measurement by electrical method; it is more precise, to the method of the introduction of charge into the tested object.
With the increasing average in years of use of transformers, there is an increasing need to ascertain transformer condition. Therefore, it is of vital importance to establish monitoring and diagnostic techniques capable of assessing transformer operating conditions. Frequency response analysis, generally known within the industry as FRA, is one diagnostic technology applied to transformers. The crucial...
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