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

Zhang, Daning; Long, Guanwei; Li, Yang; Mu, Hai‐Bao; Zhang, Guanjun

doi:10.3390/polym12061219

Cited by 8 publications

(5 citation statements)

References 20 publications

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“…The oil-immersed transformer is the core equipment of power transmission in the power grid, wherein safety and stability are significantly important to energy security and social stability. According to statistics, fault of bushing is one of the main causes for transformer faults, and the cellulose polymer paper, as the main insulation material of bushing, is the main factor contributing to the fault of bushing after moisture invaded [1][2][3]. To ensure the safe operation and stability of the transformer, it is necessary to analyze the time-domain relaxation behavior of carriers at high applied voltage with various moisture contents.…”

Section: Introductionmentioning

confidence: 99%

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

et al. 2022

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Cellulose insulation polymer material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

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Section: Introductionmentioning

confidence: 99%

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

et al. 2022

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“…1. One end of the high-voltage bushing ( 2) is connected to the high-voltage bus (1). The other end is connected to the transformer (3) body, and the voltage transformer ( 4) is installed on the incoming line side of the high-voltage bus.…”

Section: Dielectric Response Test Scheme Of the Bushingmentioning

confidence: 99%

“…Among them, oilimmersed paper insulation equipment such as large power transformers and high-voltage bushings have the most noticeable impact on the stable operation of the power grid. Therefore, the safe and stable operation of the bushing directly affects the stability of the whole power grid and is of great significance for diagnosing and evaluating its insulation state [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

A New technology of transformer bushing state detection based on transient dielectric response

Sun

Zhang²,

Feng³

et al. 2023

J. Phys.: Conf. Ser.

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Failure of the transformer bushing will cause the transformer to be powered down or damaged, affecting the safe operation of the power system. This paper proposes a method using system harmonics as the dielectric response excitation source and studies the transformer bushing insulation online detection technology based on transient dielectric response characteristics. The technical scheme and system structure of the online monitoring technology of transformer bushing insulation based on dielectric response characteristics are given. A calculation model of short-circuit grounding and capacitor switching of a 35kV substation was established, and the harmonic frequency content and amplitude distribution of grid disturbance were analyzed. A case of dielectric response measurement of the bushing is given. The research shows that the system will generate overvoltage in short circuit grounding, capacitor switching, etc. The system harmonic frequency is in the range of the dielectric response test frequency band (1Hz~1kHz), and the harmonic amplitude is also large, which can be used as an excitation source. The excitation source of the dielectric response test causes a change in the dielectric response of the transformer bushing and acts as a “probe” that reflects the insulation state of the bushing. The medium and high-frequency bands of the dielectric spectrum in the frequency domain are also sensitive to moisture, which can be used to diagnose the insulation state of the bushing.

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“…If the classification margin of the two types of sample data reaches the maximum, the hyperplane in Equation (3) will become the optimal hyperplane, which can be expressed by Equation (5).…”

Section: The Introduction Of Svmmentioning

confidence: 99%

“…Power transformers perform a vital task of transforming electrical energy in power systems, and the condition evaluation of its internal oil/paper system has attracted wide attention [ 1 , 2 , 3 , 4 , 5 , 6 ]. In recent years, a prevailing method of moisture determination is the so-called frequency domain spectroscopy (FDS) [ 7 , 8 , 9 , 10 ] technique, which is also called dielectric frequency response (DFR) technique.…”

Section: Introductionmentioning

confidence: 99%

Moisture Prediction of Transformer Oil-Immersed Polymer Insulation by Applying a Support Vector Machine Combined with a Genetic Algorithm

Zhang

Fan

et al. 2020

Polymers

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The support vector machine (SVM) combined with the genetic algorithm (GA) has been utilized for the fault diagnosis of transformers since its high accuracy. In addition to the fault diagnosis, the condition assessment of transformer oil-immersed insulation conveys the crucial engineering significance as well. However, the approaches for getting GA-SVM used to the moisture prediction of oil-immersed insulation have been rarely reported. In view of this issue, this paper pioneers the application of GA-SVM and frequency domain spectroscopy (FDS) to realize the moisture prediction of transformer oil-immersed insulation. In the present work, a method of constructing a GA-SVM multi-classifier for moisture diagnosis based on the fitting analysis model is firstly reported. Then, the feasibility and reliability of the reported method are proved by employing the laboratory and field test experiments. The experimental results indicate that the reported prediction model might be serviced as a potential tool for the moisture prediction of transformer oil-immersed polymer insulation.

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

Cited by 8 publications

References 20 publications

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

A New technology of transformer bushing state detection based on transient dielectric response

Moisture Prediction of Transformer Oil-Immersed Polymer Insulation by Applying a Support Vector Machine Combined with a Genetic Algorithm

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