Modeling of relaxation phenomena in transformer oil-paper insulation for understanding dielectric response measurements

Ojha, S. K.; Purkait, P.; Chakravorti, S.

doi:10.1109/tdei.2016.7736885

Cited by 32 publications

(22 citation statements)

References 38 publications

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“…The conduction loss is mainly reflected in the low frequency band. According to theoretical derivation [ 12 ], when the frequency is low enough, the polarization process has sufficient time to complete. At this time, the conductivity process in the oil-paper insulation medium is dominant, and the corresponding low-frequency C ″- f curve is a straight line with a slope of –1.…”

Section: Analysis Of Measurement Resultsmentioning

confidence: 99%

Effect of Radial Moisture Distribution on Frequency Domain Dielectric Response of Oil-Polymer Insulation Bushing

Zhang

Long

et al. 2020

Polymers

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In order to realize the diagnosis of water distribution, this paper analyzes the interface polarization and macroscopic space charge polarization mechanism when the water distribution is non-uniform. The experimental results of this paper and bushing show that when the moisture distribution is non-uniform, there is a significant loss peak in the tanδ-f curve. The loss peak shifts to higher frequencies as the non-uniformity coefficient increases. There are common intersection points between multiple tanδ-f curves. Further, this paper realizes the diagnosis of the location of moisture distribution through Frequency Domain Spectroscopy (FDS) testing of different voltages and different wiring methods based on the macroscopic space charge polarization. In the single-cycle FDS test, when the positive electrode is first added to the area with higher moisture content, the amplitude of the tanδ-f curve is smaller. The tanδ-f curves under different wiring methods constitute a “ring-shaped” loss peak. As the voltage increases, the peak value of the loss peak shifts to the lower frequency band. As the temperature increases, the peak value of the loss peak shifts to higher frequencies. Based on the above rules and mechanism analysis, this research provides a new solution for the evaluation of moisture content of oil-immersed polymers equipment.

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Section: Analysis Of Measurement Resultsmentioning

confidence: 99%

Effect of Radial Moisture Distribution on Frequency Domain Dielectric Response of Oil-Polymer Insulation Bushing

Zhang

Long

et al. 2020

Polymers

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“…Studies of dielectric spectrum characteristics of materials mainly focus on the qualitative characterization [28]. Dielectric response function based on the classical ''single relaxation time'' Debye model has been proposed by various researchers to model the experimental data [29]. D. K. Das-Gupta et al discussed different relaxation models (Debye model, Cole-Cole model, Davidson-Cole model, Havriliak-Negami two-parameter model) and their possible implication in the interpretation of the relaxation spectra of polymers [30].…”

Section: Thermal Performance Analysismentioning

confidence: 99%

“…D. K. Das-Gupta et al discussed different relaxation models (Debye model, Cole-Cole model, Davidson-Cole model, Havriliak-Negami two-parameter model) and their possible implication in the interpretation of the relaxation spectra of polymers [30]. S. K. Ojha et al estimated function representing distribution of relaxation frequencies [29]. Cole-Cole model and modified Cole-Cole model have been widely used to extract characteristics of frequency dielectric spectroscopy of oil-paper insulation [31]- [34].…”

Section: Thermal Performance Analysismentioning

confidence: 99%

Morphological, Structural, and Dielectric Properties of Thermally Aged AC 500 kV XLPE Submarine Cable Insulation Material and Its Deterioration Condition Assessment

et al. 2019

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Cross-linked polyethylene (XLPE) has been widely used as insulation material for cables. In 2019, the highest voltage level AC 500 kV XLPE submarine cable has been operated in Zhoushan, China. The irreversible degradation poses a safety hazard to the operation of submarine cable. Therefore, it is necessary to investigate the physical, chemical and electrical properties of XLPE submarine cable insulation under aging condition and explore the method for its deterioration degree assessment. In this paper, the AC 500 kV XLPE submarine cable insulation material was thermally aged at 130 • C. The deterioration characteristics of materials were analyzed based on morphology, chemical structure, mechanical property, thermal property and dielectric properties. Multiple characteristic parameters were extracted and new deterioration condition assessment model was established. Results show that the physicochemical characteristic parameters including retention rate of elongation at break, carbonyl index (CI) based on FTIR, full-width at half-maximum (FWHM) of the diffraction peak based on XRD, melting enthalpy based on DSC analysis, and the dielectric characteristic parameters including modified Cole-Cole model parameter χ sα and AC breakdown strength are sensitive to deterioration condition of XLPE material. According to the change of elongation retention at break, the deterioration condition of XLPE sample was divided into enhanced stage, wear-out stage and disposal stage. The new multi-factor deterioration condition assessment model including six characteristic parameters (retention rate of elongation at break, CI, FWHM, melting enthalpy, modified Cole-Cole model parameter χ sα , AC breakdown strength) was successfully established by grey correlation analysis. The new model can reflect the property of mechanical, chemical, thermal and dielectric property and has prominent effect in differentiating deterioration degree of the AC 500 kV XLPE submarine cable insulation material. INDEX TERMS Cross-linked polyethylene (XLPE), thermal aging, physicochemical properties, dielectric properties, condition assessment.

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“…2. Both polarization and depolarization currents, i p and i d respectively, are dependent on the geometry of the insulation [14], [23] and also properties of the insulating material [24], [25]. In the same figure, t polarization and t depolarization refer to the polarization and depolarization times, respectively.…”

Section: A Pdc Measurement Principlesmentioning

confidence: 99%

Determining the Number of Parallel RC Branches in Polarization / Depolarization Current Modeling for XLPE Cable Insulation

Sulaiman¹,

Ariffin²,

Kien³

2017

International Journal on Advanced Science, Engineering and Information Technology

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An important element in the electric power distribution system is the underground cable. However continuous applications of high voltages unto the cable may lead to insulation degradations and subsequent cable failure. Since any disruption to the electricity supply may lead to economic losses as well as lowering customer satisfaction, the maintenance of cables is very important to an electrical utility company. Thus, a reliable diagnostic technique that is able to accurately assess the condition of cable insulation operating is critical, in order for cable replacement exercise to be done. One such diagnostic technique to assess the level of degradation within the cable insulation is the Polarization / Depolarization Current (PDC) analysis. This research work attempts to investigate PDC behaviour for medium voltage (MV) cross-linked polyethylene (XLPE) insulated cables, via baseline PDC measurements and utilizing the measured data to simulate for PDC analysis. Once PDC simulations have been achieved, the values of conductivity of XLPE cable insulations can be approximated. Cable conductivity serves as an indicator of the level of degradation of XLPE cable insulation. It was found that for new and unused XLPE cables, the polarization and depolarization currents have almost overlapping trendlines, as the cable insulation's conduction current is negligible. Using a linear dielectric circuit equivalence model as the XLPE cable insulation and its corresponding governing equations, it is possible to optimize the number of parallel RC branches to simulate PDC analysis, with a very high degree of accuracy. The PDC simulation model has been validated against the baseline PDC measurements.

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Modeling of relaxation phenomena in transformer oil-paper insulation for understanding dielectric response measurements

Cited by 32 publications

References 38 publications

Effect of Radial Moisture Distribution on Frequency Domain Dielectric Response of Oil-Polymer Insulation Bushing

Effect of Radial Moisture Distribution on Frequency Domain Dielectric Response of Oil-Polymer Insulation Bushing

Morphological, Structural, and Dielectric Properties of Thermally Aged AC 500 kV XLPE Submarine Cable Insulation Material and Its Deterioration Condition Assessment

Determining the Number of Parallel RC Branches in Polarization / Depolarization Current Modeling for XLPE Cable Insulation

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