Modeling oil-paper insulation frequency domain spectroscopy based on its microscopic dielectric processes

Abstract

The present study sets out to devise a universal function model to explain the characteristic curve obtained in the frequency domain spectroscopy (FDS) test on oil paper insulation, based on its microscopic conduction and relaxation processes, and thus to enhance the accuracy and applicability of the test. First, from the analysis of the relationship between the real and imaginary parts of the dielectric's complex permittivity, it is demonstrated that a relaxation peak co-exists with the conduction process in the low-frequency band of an FDS curve obtained for oil-impregnated paper sample. Second, values for polarization barrier heights, essential to the determination of the microscopic polarization mechanisms, are presented as results of FDS and thermally stimulated depolarization current experiments carried out on oil impregnated paper samples. The polarization peaks obtained in the imaginary permittivity frequency spectrum are determined as, respectively, space charge polarization and interface polarization. Finally, a function model in good agreement with experiment data is proposed, which quantitatively describes the FDS curve in oil impregnated sample, including two relaxation processes and one conduction process.

Analysis of low‐frequency polarisation behaviour for oil‐paper insulation using logarithmic‐derivative spectroscopy

“…It is presented that the ε *( ω ) processed by LD could also form an obvious ‘peak’ in low‐frequency regions by using oil‐paper insulation. In literature [24], the temperature effect on LDS itself is analysed, which is based on another original formula for LD calculation. Further, if the polarisation information can be extracted in the research, the observed results are interesting and deserve further attention.…”

“…Given these issues, an alternative idea is reported to extract the polarisation information from the total FDS data by using logarithmic‐derivative spectroscopy (LDS). In the current work, the LDS of oil‐paper insulation is first calculated by using the logarithmic‐derivative (LD) method [23, 24]. Findings revealed that the mathematical formula for extracting the polarisation information can be derived using LDS.…”

Physical Model for Frequency Domain Spectroscopy of Oil–Paper Insulation in a Wide Temperature Range by a Novel Analysis Approach

“…Take this as a reference, Figure 6 reveals each peak's accumulated charge quantities QTSDC under different bias voltages. According to [21], it could be inferred from Figure 6 that the QTSDC of Relaxation A remains positive and is in a linear correlation with the bias voltage amplitude; this indicates that Relaxation A is dominated by a dipole. Meanwhile, the QTSDC of Relaxation C changes from positive to negative when the bias voltage turns to positive, the variation law of which is consistent with electrode polarization.…”

“…Meanwhile, the QTSDC of Relaxation C changes from positive to negative when the bias voltage turns to positive, the variation law of which is consistent with electrode polarization. As regards Relaxation B, the relationship between its accumulated charge quantity and According to [21], it could be inferred from Figure 6 that the Q TSDC of Relaxation A remains positive and is in a linear correlation with the bias voltage amplitude; this indicates that Relaxation A is dominated by a dipole. Meanwhile, the Q TSDC of Relaxation C changes from positive to negative when the bias voltage turns to positive, the variation law of which is consistent with electrode polarization.…”

Ageing state identification and analysis of AC 500 kV XLPE submarine cable based on high‐voltage frequency dielectric response

“…In recent years, the frequency dielectric spectroscopy (FDS) method has been widely used in evaluating the insulation condition of cables, due to its advantage of non-destructive [6][7][8][9]. Wang et al [10] performed FDS measurement on 10 kV XLPE cable with different ageing conditions under 200 V testing voltage.…”