Influence of the geometrical parameters of power transformer insulation on the frequency domain spectroscopy measurement

Pradhan, Manoj Kumar; Yew, J.H.; Saha, Tapan Kumar

doi:10.1109/pes.2008.4596601

Cited by 15 publications

(8 citation statements)

References 10 publications

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“…The DDF of a dielectric material is a complex function of at least two variables-frequency and temperature, although aging, moisture and pressure may be other physical variables [4][5][6][7][8][9][10][11][12][13][14][15][16]. A complete representation should therefore be "three-dimensional" plots, but these are cumbersome and are therefore seldom employed, although modern computer graphics enable one to plot third-angle projections in two dimensions.…”

Section: Results Of the Investigationsmentioning

confidence: 99%

“…This correlation is clearly highlighted by the linear trend-line reported in the Figure 14. Recall that the frequency vs. dissipation factor relationship response curve for oil-impregnated paper is well known to display moisture and ageing impact at higher and lower frequencies with much clearer indication in the very lower frequencies (below millihertz range) [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The interpretation scheme must allow a separation between these parameters.…”

Section: Moisture Content In Oil-paper Insulation Estimationmentioning

confidence: 99%

“…Over the last decades, the increasing requirements for appropriate tools to diagnose power equipments insulation non-destructively and reliably in the field drive the development of diagnostic tools based on changes of the dielectric properties of the insulation. Among these tools time domain measurement based on Polarization/Depolarization Current (PDC) and Frequency Domain Spectroscopic (FDS) measurements are gaining exceptional importance to the utility professionals [7][8][9][10][11][12][13][14][15]. The FDS is the favoured choice for on-site measurements due to its robustness against noise.…”

Section: Introductionmentioning

confidence: 99%

“…The FDS is the favoured choice for on-site measurements due to its robustness against noise. In the last decades, much study and work has been performed with the aim of improving our basic understanding of dielectric response interpretation schemes (e.g., [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]). It is now accepted that Frequency Domain Spectroscopy (FDS) measurement techniques provide indication of the general ageing status and moisture content of the oil-paper insulation of transformer.…”

Section: Introductionmentioning

confidence: 99%

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On the Feasibility of Using Poles Computed from Frequency Domain Spectroscopy to Assess Oil Impregnated Paper Insulation Conditions

et al. 2013

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Frequency Domain Spectroscopy (FDS) is an effective tool allowing assessing the condition of oil-paper insulation system in power equipment. However, results from these measurements are known to be greatly influenced by various parameters, including insulation aging, moisture content, and insulation geometry/volume, together with environmental condition such as temperature. In this contribution, a series of experiments have been performed under controlled laboratory conditions. The dielectric response of the oil impregnated paper, along with the degree of polymerization and moisture content, were monitored. Since dielectric parameters are geometry dependent, poles (independent of the geometry) which depends on resistivity and permittivity, were considered to assess the condition of the insulation. From the investigations performed on new and aged samples, it is shown that poles (P) can be regarded as insulation aging indicator. It is also shown that a per unit value based on the Dielectric Dissipation Factor (DDF), measured in the frequency range from 1 to 1000 Hz can be correlated to moisture content in the insulation paper.

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Section: Results Of the Investigationsmentioning

confidence: 99%

Section: Moisture Content In Oil-paper Insulation Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Feasibility of Using Poles Computed from Frequency Domain Spectroscopy to Assess Oil Impregnated Paper Insulation Conditions

et al. 2013

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“…Through this method, slow polarization processes of the insulation are examined by measuring magnitudes and phase angles of currents [25,90,94]. With a single frequency is considered at a time, the resultant current can be defined as [25,90]:…”

Section: Frequency Domain Spectroscopy (Fds)mentioning

confidence: 99%

Advanced signal processing techniques for online power transformer insulation diagnosis

Chan¹

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Power transformer is one of the most important assets in an electric utility. However, a large number of existing power transformers worldwide have already approached or even exceeded their designed lifetimes. Any failure of a transformer can be disastrous. Therefore, the conditions of transformers need to be continuously monitored and evaluated. Since a transformer's condition is largely dependent on its insulation system, a number of diagnostic methods have been developed for assessing transformer insulation conditions over the past decades. Among these methods, partial discharge (PD) measurement is widely adopted due to its capability of providing continuously online monitoring and diagnosis of a transformer without disturbing its normal operation.PD is a rather complicated phenomenon and stochastic in nature. Properly performing online PD measurements of a transformer, effectively analysing the measured PD signals, and subsequently making an informed condition assessment on a transformer's insulation system are still challenging.This thesis is aimed at developing advanced signal processing techniques for online PD monitoring and diagnosis of power transformer insulation systems.PD signals acquired at substation environments are always coupled with extensive noise, which exhibits different distribution properties. Therefore, PD signal de-noising is an essential process for accurately extracting PD signals from the acquired noise-corrupted signals before further analysis. In this thesis, advanced signal processing techniques, such as wavelet transform (WT), empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD), blind equalization (BE) and pre-whitening, have been investigated for removing discrete spectral interference (DSI) that exhibits sinusoidal behaviour at various frequencies. Mathematical morphology (MM) has also been investigated for suppressing white noise by adaptively selecting threshold values. To remove stochastic noise, fractal dimension and entropy analyses have been investigated. Based on these techniques, several adaptive PD signal de-noising methods have been proposed in this thesis for removing different types of noise. A number of case studies using PD signals acquired from both laboratory experiments and online PD measurements of field transformers are presented. These case studies demonstrate advantages of the proposed PD signal de-noising methods over conventional methods in PD signal de-noising.In this thesis, phase-resolved pulse sequence (PRPS) diagrams and kurtograms have also been proposed for consistent representations of PD patterns after the noise has been removed. Case studies have been provided to prove a PRPS diagram's capability for accurately and consistently ii representing PD patterns. This representation can minimize influences of different types of PD sensors and measurement systems on PD pattern construction. Results are presented to demonstrate that kurtograms can be used to represent PD patterns even in the presence of extensive w...

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Dielectric Response Measurements

Saha¹,

Purkait²

2017

Transformer Ageing

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Influence of the geometrical parameters of power transformer insulation on the frequency domain spectroscopy measurement

Cited by 15 publications

References 10 publications

On the Feasibility of Using Poles Computed from Frequency Domain Spectroscopy to Assess Oil Impregnated Paper Insulation Conditions

On the Feasibility of Using Poles Computed from Frequency Domain Spectroscopy to Assess Oil Impregnated Paper Insulation Conditions

Advanced signal processing techniques for online power transformer insulation diagnosis

Dielectric Response Measurements

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