Moisture estimation for oil‐immersed bushing based on FDS method: field application

Wang, Dongyang; Zhou, Lijun; Liao, Wei; Wang, An; Xu, Xiaowei; Guo, Lan-Ping

doi:10.1049/iet-gtd.2018.0194

Cited by 18 publications

(4 citation statements)

References 24 publications

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“…Measurements were performed at six measurement temperatures: 293. 15 This had a positive impact on the accuracy of the determination of the activation energy of the direct and alternating current conductivity of the oil-impregnated pressboard.…”

Section: Methodsmentioning

confidence: 99%

“…To test the moisture content of power transformer insulation, diagnostic methods based on relaxation changes in the time domain using the recovery voltage method (RVM) [3][4][5][6] and polarization depolarization current (PDC) method [7][8][9][10] are used. In the frequency domain, however, the values of the loss factor tgδ and system capacity at low frequencies are determined using the frequency domain spectroscopy (FDS) method [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Precise Measurements of the Temperature-Frequency Dependence of the Conductivity of Cellulose—Insulating Oil—Water Nanoparticles Composite

et al. 2020

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This article presents direct σDC and alternating σ(f) current conductivity measurements obtained by the frequency domain spectroscopy (FDS) method on cellulose-transformer oil–water nanoparticle composite with a moisture content of (5.0 ± 0.2)% by weight in a temperature range from 293.15 to 333.15 K with step of 8 K. The uncertainty of temperature maintenance during measurements was below ±0.01 K. The sample was prepared for testing in a manner as close as possible to the cellulose insulation moisturizing process in power transformers. For the analysis of the results obtained, a model of alternating and direct current hopping conductivity was used, based on the quantum phenomenon of electron tunneling between the potential wells and nanodrops of water. It was observed that on the d(logσ)/d(logf)-derived waveforms there was a clear low-frequency maximum, and a tendency to reach the next maximum in the high-frequency area was visible. On this basis it was established that the increase in conductivity takes place in two stages. It was found that the position of σ(f) waveforms in the double logarithmic coordinates is influenced by the temperature dependence both of the conductivity and of the relaxation time of the conductivity. These relationships are described with the appropriate activation energies of the conductivity and relaxation time of conductivity. Based on the analysis of experimental data using Arrhenius diagrams, average values of the activation energy of conductivity ΔWσ ≈ (0.894 ± 0.0134) eV and the relaxation time of conductivity ΔWτσ ≈ (0.869 ± 0.0107) eV were determined. The values were equal within the limits of uncertainty and their mean value was ΔW ≈ (0.881 ± 0.0140) eV. Using the mean value of the activation energy, the frequency dependence of conductivity, obtained at different temperatures, was shifted to 293.15 K. For this purpose, first the waveforms were shifted along the horizontal and then the vertical axis. It was found that after the shift the σ(f) waveforms for the different temperatures overlap perfectly. This means that the shape of the frequency dependence of the conductivity is determined by the moisture content of the pressboard. The position of the waveforms in relation to the coordinates is determined by the temperature relationships of the conductivity and the relaxation time of the conductivity.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Precise Measurements of the Temperature-Frequency Dependence of the Conductivity of Cellulose—Insulating Oil—Water Nanoparticles Composite

et al. 2020

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“…Moreover, the authors in Refs. [14,15] introduced a method, based on the FDS results, for assessing the OIP bushing's moisture level. Additionally, they have realised that the temperature can affect the values of tanδ.…”

Section: Introductionmentioning

confidence: 99%

Assessing the moisture content of oil‐impregnated paper bushings with a simple and fast method

Ansari,

Vahedi

2023

IET Electric Power Appl

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Power outages can cause harm to both society and individual health. Among the crucial elements of power systems, power transformers play a vital role, and their failures can lead to incidents and disruptions. According to statistics, almost 50% of the explosions and fires in the power transformer are caused by oil‐impregnated paper (OIP) bushing failures. Moreover, moisture is a crucial factor that affects the health of OIP bushings, and assessing the moisture level in OIP bushings is vital to guarantee the safety of power systems. While the frequency‐domain dielectric spectroscopy (FDS) method has been widely used to assess the moisture content of OIP bushings on‐site, it has the disadvantage of requiring a long measurement time. Therefore, a novel technique was proposed in this study that involves measuring the OIP bushing dissipation factor (tanδ) at 1 Hz to estimate the moisture content in a significantly shorter time. Five samples of OIP with various moisture levels have been selected, and an equation based on the OIPs' value of tanδ at 1 Hz was proposed to assess the moisture level of OIP bushings. Furthermore, the validity of the proposed method was successfully verified, proving its precision and time efficiency.

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“…What should be noted is that moisture can be produced during the thermal aging process of the internal insulation. Besides, due to the loose of nut, cracks in external insulation and poor sealing of oil pillow, the invasion of external moisture from the environment is the main way in field [15], [16]. For oil-immersed insulation paper, moisture is a harmful agent that catalyzes the thermal aging reactions and accelerates the aging process, which reduces the dielectric strength, decreases the partial-discharge inception voltage and increases the fault probability [17].…”

Section: Introductionmentioning

confidence: 99%

Simulation for Transient Moisture Distribution and Effects on the Electric Field in Stable Condition: 110 kV Oil-Immersed Insulation Paper Bushing

et al. 2019

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Oil-immersed insulation paper (OIP) bushing is one of the most important equipment in power transmission and distribution systems. Moisture is one of the most serious factors that affect the insulation status of OIP bushing. In this paper, the OIP bushing was assumed to be in a stable and simplicity condition, and then the transient moisture distribution of capacitor core and its effects on the electric field were studied. First, by dissecting a 110 kV OIP bushing, the specific sizes for modelling were obtained. Afterwards, a moisture diffusion model for OIP bushing was established based on COMSOL Multiphysics software, and it was also verified by moisture diffusion experiment. Then, the moisture distribution for different conditions were obtained and analyzed. Finally, a model for the electric field of OIP bushing was established, and then the effects of moisture on the electric field were studied. INDEX TERMS Oil-immersed insulation paper (OIP) bushing, 110 kV, capacitor core, transient moisture distribution, electric field.

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Moisture estimation for oil‐immersed bushing based on FDS method: field application

Cited by 18 publications

References 24 publications

Precise Measurements of the Temperature-Frequency Dependence of the Conductivity of Cellulose—Insulating Oil—Water Nanoparticles Composite

Precise Measurements of the Temperature-Frequency Dependence of the Conductivity of Cellulose—Insulating Oil—Water Nanoparticles Composite

Assessing the moisture content of oil‐impregnated paper bushings with a simple and fast method

Simulation for Transient Moisture Distribution and Effects on the Electric Field in Stable Condition: 110 kV Oil-Immersed Insulation Paper Bushing

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