S. Grzybowski

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Wavelet shrinkage methods are effective for de-noising of partial discharge (PD) detection. Base wavelets are related to distortion of PD signals de-noised by wavelet shrinkage methods. This paper presents a scale dependent wavelet selection scheme for de-noising of PD detection. The scale dependent wavelet selection scheme is called the energy based(More)
This paper presents an integrated model based upon the fuzzy approach and evidential reasoning decision-making approach to condition assessment of power transformers. An assessing index system, including the DGA data, electrical testing, and oil testing, is established to facilitate the assessing model. The model is composed of two levels, that is, the(More)
Wavelet shrinkage is efficient for de-noising the partial discharge (PD) detection. An improved wavelet de-noising approach for PD online measurement is presented. The wavelet de-noising approach is based on a genetic adaptive threshold estimation (GATE) scheme. The thresholding functions with continuous derivatives are used for the GATE scheme. A genetic(More)
The estimated number of lightning flashes to a transmission line is the vital parameter to evaluate the lightning performance precisely. An experimental study on the factors that have an impact on the number of lightning flashes to transmission lines has been performed at the MSU High Voltage Laboratory. Models of typical transmission lines with different(More)
This paper presents aging condition assessment of oil-paper transformer insulation based on partial discharge analysis in order to realize statistical parameters reduction. The extracted feature factors of this proposed model were used to identify oil-paper samples with different aging degrees. An accelerated aging test was implemented using artificial(More)
In order to analyze the thermal aging mechanism of the insulation paper inside the power transformer, a series of accelerated thermal aging tests were performed on pressboard. Subsequently, the atomic force microscope (AFM) together with scanning electron microscope (SEM) and X-ray diffraction (X-RD) were utilized to observe the micro surface of the(More)
This paper presents a quadtree partitioning fractal image compression (QPFIC) method used for the partial discharge (PD) image remote recognition system. Self-similarity in PD images is the premise of fractal image compression and is described for the typical PD images acquired from defect model experiments in laboratory. Influences of fractal image(More)
This paper presents the electric properties of a type of refined rapeseed oil, which can be used as transformer oil. The lifetime of the rapeseed oil-immersed paper is estimated by performing the step-stress test. Two Weibull parameters are used for statistical analysis of mean lifetime of oil-paper specimen. The mathematic models, the inverse power model,(More)
The objective of this paper is to present the results of a study on the effect of multistress on the lifetime characteristics of magnet wires. The enamel coating on a magnet wire is subjected to multistress aging factors such as electrical, thermal and other environmental stresses. In order to identify the most important factors that contribute to the(More)
Even in lightning protection of a complicated object, a Franklin rod is the most common and effective device used to protect the ship. Based on review of the previous study on EGM and recent theoretical exploration of lightning striking distance, an elliptical model of lightning protection zone is established by the Mississippi State University HV Lab. The(More)