Influence of metal transformer materials on oil-paper insulation after thermal aging

Deng, Wei; Zhu, Zengwei; Zhang, Li; Qian, Yihua; Su, Wei; Chen, Tiansheng; Fan, Shengping; Zhao, Yaohong

doi:10.1109/tdei.2018.007546

Cited by 22 publications

(6 citation statements)

References 19 publications

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“…The basic component of insulating paper for oil-immersed transformers is cellulose, it is formed by D-glucose through β-1,4-glycosidic linkage (Gao et al 2019). The degree of polymerization of cellulose molecules is the number of glucose monomers, the degree of polymerization of the newly-running transformer insulation paper is between 1000 and 1200 (Wang et al 2019). Mazeau et al (2003) conducted simulation experiments with cellulose chains of different lengths.…”

Section: Reaxff-md Simulation Detailsmentioning

confidence: 99%

WITHDRAWN: Microscopic Reaction Mechanism of Formic Acid Generated During Pyrolysis of Cellulosic Insulating Paper

Zheng

Yang

et al. 2021

Preprint

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Cellulosic insulating paper is the component part of the insulation in power transformers. Under thermal stress inside the transformer, cellulosic insulating paper degrades to generate formic acid that will dissolve in insulating oil. In addition, the generation of formic acid further accelerates the aging process of insulating paper. This study took cellulose molecule with DP of 2 that was composed of D-glucose as the research object, the ReaxFF reaction force field was used to simulate the high temperature thermal aging process of cellulose. This study obtained the main reaction pathways of cellulose pyrolysis to generate formic acid. During the pyrolysis process, the number of formic acid molecules presented short-term fluctuations, which was the phenomenon of disappearance and regeneration of formic acid molecules. The combined element tracing method obtained three pathways of cellulose pyrolysis to generate formic acid: 1) The ether group oxygen atom O5(O'5) and C1(C'1) form a carbonyl group to generate formic acid. 2) Dehydrogenation of the primary alcohol hydroxyl group and the attached C atom form a carbonyl group to generate formic acid. 3) Dehydrogenation of the secondary alcohol hydroxyl group and the attached C atom form a carbonyl group to generate formic acid. Statistics found that the generation of formic acid molecules mainly come from the first pathway. The pre-exponential factor and activation energy of the calculated pyrolysis model were consistent with the experimental results. This study designed the accelerated thermal aging experiment of oil-paper insulation. The silanization derivatization method was used to detect the formic acid generated by the aging of insulating paper, which further verified the feasibility of formic acid as an index for evaluating the aging of cellulosic insulating paper.

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Section: Reaxff-md Simulation Detailsmentioning

confidence: 99%

WITHDRAWN: Microscopic Reaction Mechanism of Formic Acid Generated During Pyrolysis of Cellulosic Insulating Paper

Zheng

Yang

et al. 2021

Preprint

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“…It can be seen from formula (10) and formula (11) that the zero-order ageing kinetic model believes that the ageing rate of insulation paper is only related to the experiment temperature and activation energy, and the activation energy is a physical quantity to measure the difficulty of low-energy molecules obtaining energy from the outside to become high-energy molecules within a certain temperature range and it can be considered as a constant due to its small change range. Therefore, when analysing the accelerated thermal ageing data at constant temperature, the ageing rate shown in formula (11) is regarded as a fixed value.…”

Section: Time Varying Pre Exponential Factor and Its Relationship Wit...mentioning

confidence: 99%

“…Practically, it is not convenient to test the DP as the sampling process needs to hang the core and the sampling will damage the insulation of the transformer. To solve this problem, various indirect measurement methods were proposed in [8][9][10][11], such as furfural content, acid value test, and frequency domain dielectric spectroscopy (FDS) methods. The main idea of these methods is to propose characteristic parameters based on the test results, establish the mapping relationship between characteristic parameters and DP, and then realize the evaluation of DP.…”

Section: Introductionmentioning

confidence: 99%

Degree of polymerisation estimation for insulation paper immersed in silicone oil using frequency domain dielectric spectroscopy

Zhou,

Zhang,

et al. 2023

High Voltage

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Frequency domain dielectric spectroscopy (FDS) is an effective method reflecting the changes of ageing status of silicone oil‐immersed insulation paper. For better evaluating the ageing status of silicone oil‐immersed insulation paper, an evaluation method was studied by analysing the ageing kinetic model and results of FDS. First, the method to separate the different polarization losses and conductivity loss from the results of FDS was studied. Then, based on the idea of ageing correction translation coefficient and time‐varying pre exponential factor, the zero order ageing dynamic model was modified, which combines the ageing kinetic model with the results of FDS. Finally, the evaluation method for the degree of polymerisation (DP) of silicone oil‐immersed paper was proposed, and experiments were conducted to obtain the parameters in the modified model and then to verify the proposed method. The results show that the proposed method can be used to evaluate the DP effectively.

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“…Cellulose is the main component of the insulation paper. In addition, cellobiose is the repeating unit of cellulose [21], and the DP of new insulation paper is between 1000 and 1200 [22]. However, it is impractical to model molecules with thousands of DPs directly.…”

Section: Model Constructionmentioning

confidence: 99%

A Molecular Dynamics Study of the Generation of Ethanol for Insulating Paper Pyrolysis

Zhang

et al. 2020

Energies

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Cellulosic insulation paper is usually used in oil-immersed transformer insulation systems. In this study, the molecular dynamics method based on reaction force field (ReaxFF) was used to simulate the pyrolysis process of a cellobiose molecular model. Through a series of ReaxFF- Molecular Dynamics (MD) simulations, the generation path of ethanol at the atomic level was studied. Because the molecular system has hydrogen bonding, force-bias Monte Carlo (fbMC) is mixed into ReaxFF to reduce the cost of calculation by reducing the sampled data. In order to ensure the reliability of the simulation, a model composed of 20 cellobioses and a model composed of 40 cellobioses were respectively established for repeated simulation in the range of 500–3000 K. The results show that insulating paper produced ethanol at extreme thermal fault, and the intermediate product of vinyl alcohol is the key to the aging process. It is also basically consistent with others’ previous experiment results. So it can provide an effective reference for the use of ethanol as an indicator to evaluate the aging condition of transformers.

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Influence of metal transformer materials on oil-paper insulation after thermal aging

Cited by 22 publications

References 19 publications

WITHDRAWN: Microscopic Reaction Mechanism of Formic Acid Generated During Pyrolysis of Cellulosic Insulating Paper

WITHDRAWN: Microscopic Reaction Mechanism of Formic Acid Generated During Pyrolysis of Cellulosic Insulating Paper

Degree of polymerisation estimation for insulation paper immersed in silicone oil using frequency domain dielectric spectroscopy

A Molecular Dynamics Study of the Generation of Ethanol for Insulating Paper Pyrolysis

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