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A Molecular Dynamics Study on the Influence of Atmosphere on the Characteristics of Thermal Decomposition Products of Cross-Linked Epoxy Resins in Composite Insulators 18th

A Molecular Dynamics Study on the Influence of Atmosphere on...

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18th Annual Conference of China Electrotechnical Society, ACCES 2023

作者： Zhiyu, Wan Dandan, Zhang Chao, Gao Ming, Lu Zhenbiao, Li Junjie, Lin Yuwei, You Ziheng, Huang Luqing, Cheng Zehong, Wang School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Zhengzhou450052 China

ISBN: (纸本)9789819713509

The degradation of the epoxy resin matrix, triggered by partial discharges within composite insulators, is a prominent phenomenon in decay-like fracture incidents. The decomposition products of epoxy resins could significantly influence the further progression of these incidents. This study establishes crosslinked and non-crosslinked models of epoxy resin molecules, employing molecular dynamics methods to investigate the characteristics of the thermal decomposition products of epoxy resins within composite insulators. The effects of an oxygen atmosphere and a crosslinking network on the properties of pyrolysis small molecule products are also examined. Results demonstrated that the introduction of oxygen notably impacts the thermal decomposition products of small molecules, leading to an increase in CO2 and H2O yields, with no significant effect on CH2O yield. The presence of oxygen also results in an increase in the types and quantities of C2 and C3 products, particularly oxygen-containing compounds. Compared to non-crosslinked epoxy resins, the impact of oxygen on CO2 yield during the thermal decomposition process of crosslinked epoxy resins is relatively minor, but its effect on H2O yield is more substantial. Furthermore, regardless of the presence or absence of oxygen, the types of C2 and C3 products from crosslinked epoxy resins are fewer, implying that the crosslinking network limits intermolecular freedom, thereby resulting in enhanced oxidation reaction capabilities and more stable chemical reaction behaviors. © Beijing Paike Culture Commu. Co., Ltd. 2024.

关键词： Molecular dynamics

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Study on the Morphology Characteristics of Epoxy Resin of Composite Insulator under Acid-heat Condition 8

Study on the Morphology Characteristics of Epoxy Resin of Co...

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2022 8th International Conference on Electrical Engineering, control and Robotics, EECR 2022

作者： Pan, Wenwu Zhang, Dandan Lu, Ming Li, Zhenbiao Gao, Chao Wan, Zhiyu School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China The Key Laboratory of Pulsed Power Technology Ministry of Education Wuhan430074 China Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Songshan South Road 85 Zhengzhou China

Whether epoxy resin is degraded or not in composite insulators is the most direct criterion to distinguish Decay-like fracture from brittle fracture and normally mechanical fracture. During the actual operation of composite insulators, the nitric acid produced by partial discharge and abnormal heating will accelerate the degradation and deterioration of epoxy resin of composite insulators. In this paper, the experimental platform under acid-heat condition is built by using heating furnace, grinding bottle and serpentine condensation tube, and the acid-heat deterioration experiments are carried out under 60 °C (3 mol/L and 5 mol/L) and 80 °C (3 mol/L and 5 mol/L) condition. The macroscopic and microscopic morphologies of epoxy resin after acid-heat deterioration are analyzed, and the morphology changes of epoxy resin under the influence of acid-heat coupling field are studied. Firstly, it is concluded that the epoxy resin changes directly from colorless to light yellow, and then from light yellow to dark yellow under the influence of acid-heat deterioration. In addition, in the early stage of deterioration, the bulge on the surface of epoxy resin decreases gradually. Meanwhile, the maximum height difference and standard deviation of the surface profile of epoxy resin also gradually decreases, and the roughness decreases. In the later stage of deterioration, cracks appear on the surface of epoxy resin and some epoxy resins fall off. At the same time, the maximum height difference and standard deviation of surface profile of epoxy resin increases. © Published under licence by IOP Publishing Ltd.

关键词： Epoxy resins

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Study on the Deterioration Characteristics of ECR Glass Fiber in Composite Insulators Under Acid-Heat Conditions 18th

Study on the Deterioration Characteristics of ECR Glass Fibe...

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18th Annual Conference of China Electrotechnical Society, ACCES 2023

作者： Huang, Ziheng Zhang, Dandan Lu, Ming Gao, Chao Li, Zhenbiao Wan, Zhiyu You, Yuwei Wang, Zehong School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Ministry of Education Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Zhengzhou450052 China

ISBN: (纸本)9789819710638

During the actual operation of composite insulators, they may be affected by various deterioration factors. Acid generated by partial discharge and abnormal heating may accelerate the deterioration of ECR glass fibers in composite insulators, leading to decay-like fracture of composite insulators. In this article, the deterioration experiment of ECR glass fibers comprehensively considered the effects of acid and temperature. The acid heat deterioration experiment of ECR glass fibers were conducted to investigate the changes in morphology and mechanical properties of ECR glass fibers. The results showed that the degradation effect of acid solution on ECR glass fibers was not significant at room temperature, while the surface of ECR glass fibers deteriorated by acid heat became rough and a large amount of powdery debris appeared;Meanwhile, compared to nitric acid, oxalic acid has a more severe degradation effect on glass fibers. After 12 days of deterioration with 1mol/L oxalic acid at 80 ℃, the tensile strength and elastic modulus of glass fibers decrease by more than 90%;After acid heat degradation, there are a large number of "debris" on the surface of the glass fiber. Fiber damage and fracture phenomena occur at the same time. © Beijing Paike Culture Commu. Co., Ltd. 2024.

关键词： Tensile strength

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The Influence of Wind Load on the Mechanical Properties of the Main Transformer Bushing End of UHV Substation

The Influence of Wind Load on the Mechanical Properties of t...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Xuezhen Si Jinyang Wang Kai Xie Yaguang Tao Zhuli Liu Pengliang Ren Xiaohui Yang Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Henan China School of Mechanical and Power Engineering Zhengzhou University Henan China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

The main transformer of substation mostly works in the wild, and its bushing end is prone to deformation and fracture. This paper takes ABAQUS as the platform and a bushing end of main transformer as the research object to establish a fine finite model. And the effect of wind load on mechanical properties of the bushing end was studied by taking wind speed and direction of dangerous condition as parameters. The results show that the terminal board and the bushing terminal are the weak links of structure, with large stresses and displacements. And the end cover is warped under the compression of the bushing terminal. The research results provide a reference for the structure's design, optimization and local strengthening measure of bushing ends and substations.

关键词： Insulators Stress Conductors Substations Finite element analysis Clamps Strain

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The Influence of Down Conductor Torsion on the Mechanical Properties of the Main Transformer End of Substation

The Influence of Down Conductor Torsion on the Mechanical Pr...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Kai Xie Yaguang Tao Jinyang Wang Xiangyu Huo Zhuli Liu Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Henan China School of Mechanical and Power Engineering Zhengzhou University Henan China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

Four-bundle down conductor is prone to additional torsion in the installation process of it, which may affect the safety and stability of the end of bushing. In this paper, the down conductor of the main transformer bushing is taken as the research object, and ABAQUS as the platform. A fined finite element model is established to analyze the mechanical influence of the twisting method and twisting angle of the down conductor on the end of main transformer bushing. The results suggest that the stress of the bushing terminal and the terminal board increases non-linearly with the increase of the down conductor around its centerline or overall torsion; When the torsion angle is greater than 5°, the stress of the parts increases greatly, and the torsion angle should be controlled. The results of this paper lay the foundation for further optimizing the installation method of the main transformer bushing and improving the installation accuracy during the construction installation process.

关键词： Insulators Conductors Stress Finite element analysis Clamps Arresters Substations

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Study on Acid Thermal Aging Characteristics of Composite Insulator Core Rod Material Based on TGA and SEM 18th

Study on Acid Thermal Aging Characteristics of Composite Ins...

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18th Annual Conference of China Electrotechnical Society, ACCES 2023

作者： Zhang, Dandan You, Yuwei Pan, Wenwu Lu, Ming Gao, Chao School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Key Laboratory of Pulsed Power Technology Ministry of Education Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory of Strong Electromagnetic Engineering and New Technology Huazhong University of Science and Technology Wuhan430074 China Jiaxing Power Supply Company State Grid Zhejiang Electric Power Co. Ltd. Jiaxing314000 China Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Zhengzhou450052 China

ISBN: (纸本)9789819710713

In recent years, a novel "decay-like fracture" has emerged in China's transmission line composite insulators, posing risks to safe operation. These insulators encounter combined acid, heat, and water effects during use. Research mainly focuses on heat or acid, not reflecting actual external stresses on composite insulators. Hence, this study considers acid, heat, and water, conducting vacuum and acid thermal aging tests on bisphenol An epoxy resin. TGA and SEM analyze degraded samples. Findings show similar reaction mechanisms in intact epoxy resin at different heating rates. Changes minimally affect mass loss, keeping reaction mechanism stable. Acid thermal aging reduces activation energy, lowering the "threshold" for thermal stress erosion, degrading epoxy resin at lower temps. High-temp vacuum aging and low-temp acid aging form bubbles on epoxy resin, resembling decay. This explains minor temp rises yet severe epoxy resin degradation in decayed insulators. © Beijing Paike Culture Commu. Co., Ltd. 2024.

关键词： Thermal aging

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The study on the applicability of aluminum conductor carbon core in the high incidence area of galloping for transmission lines

The study on the applicability of aluminum conductor carbon ...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Bo Zhang Xiaohui Yang Wei Yang Bo Liu Wenjun Ai Jie Ma EPRI of Henan Zhengzhou China Device Status Assessment Center The Key Laboratory of State Grid Corporation of China on Prevention Technology of Transmission Lines Galloping Economic and technology research institute of henan electric power corporation Zhengzhou China

ISBN: (纸本)9781509004973

ACCC(Aluminum Conductor Carbon Core) is one of the most promising new conductors in the power system currently. There are more and more engineering applications. But there less study on the applications in transmission line galloping area with high incidence, and it is currently not clear that whether ACCC is not easy for galloping with small sag and light weight, and that ACCC is easy to be damaged with weak anti-bending characteristic. This paper established a galloping experimental observation span, achieved the dancing simulated ACCC by installing and adjusting the artificial ice, finished the contrast of galloping characteristics between ACCC and ACSR under natural wind excitation, confirmed that a ACCC has a less galloping-strength under low speed wind, a more high gallopingstrength under fast than ACSR. Meanwhile this paper developed a device named the transmission line galloping-simulating machine, which can simulate the state of the transmission line galloping. Using the transmission line galloping-simulating machine, this paper finished ACCC galloping fatigue test, confirmed the transmission line galloping damage weak point of ACCC proposed the measure of reducing the dancing of ACCC.

关键词： Conductors Wind speed power transmission lines transmission line measurements Carbon Fitting Aluminum

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BOTDA based side hole fiber sensing

BOTDA based side hole fiber sensing

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OptoElectronics and Communications Conference, OECC

作者： Kai Xie Yanmin Chen Zhongbing Lu Quan Chai Yanlei Liu Yongkang Dong Jianzhong Zhang Lab of transmission line galloping prevention technique State grid Henan electric power research institute Zhenzhou China Key Lab of ln-Fiber Integrated Optics of Ministry of Education Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology Harbin China

We present the first demonstration of distributed strain/temperature sensing in side hole fibers (SHFs) based on Brillouin optical time domain analysis systems (BOTDA). The Brillouin frequency shift (BFS) of 10.22 GHz and the Brillouin linewidth of 40 MHz were measured. The temperature and strain coefficients of the Brillouin frequency shift are 1.08 MHz/O and 0.089 MHz/με, respectively. Compared with other types fiber, it has lower temperature sensitivity, higher strain sensitivity.

关键词： Scattering Strain Optical fibers Temperature sensors Temperature measurement Frequency measurement

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Dynamic Response of a Cat Head Type transmission Tower-line System under Strong Wind

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Journal of Physics: Conference Series 2021年第1期1986卷

作者： Chuan Wu Xiaohui Yang Bo Zhang Zehui Liu Yang Zhao State Grid Henan Electric Power Research Institute & State Grid Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology Zhengzhou 450052 China School of Advanced Manufacturing Engineering Chongqing University of Posts and Telecommunications Chongqing 400065 China

transmission tower plays important role in the power system and it is security sensitive in various working conditions, such as wind and ice. In this paper, a method to obtain the dynamic response of a cat head type transmission tower under strong fluctuating wind was proposed. The coupled tower-lines finite element model was established in ABAQUS, and the equivalent acceleration of fluctuating wind was simulated by MATLAB. Then the displacements and stresses time histories were obtained. The method introduced in this paper can be used to assess the safety of tower under different fluctuating wind with different directions and provide a reference of the tower in the design stage.

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