High VoltagePub Date : 2024-09-25DOI: 10.1049/hve2.12484
Teng Gao, Dongxin He, Zhe Xu, Junyu Wei, Shijie Xie, Gilbert Teyssède, Zhizhen Liu, Bin Cui
{"title":"Degradation induced by charge relaxation in silicone gels under the ultra-fast pulsed electric field","authors":"Teng Gao, Dongxin He, Zhe Xu, Junyu Wei, Shijie Xie, Gilbert Teyssède, Zhizhen Liu, Bin Cui","doi":"10.1049/hve2.12484","DOIUrl":"10.1049/hve2.12484","url":null,"abstract":"<p>The insulating properties of silicone gel used for silicon carbide-insulated gate bipolar transistors encapsulation may deteriorate seriously under ultra-fast pulsed electric fields. The essence of insulation degradation lies in the deterioration of materials caused by dynamic phenomena at microscopic scale, such as charge trapping and detrapping. Different from the steady-state operating condition, insulating materials exhibit a sharp decrease in their insulating properties when subjected to a rapidly changing electric field. To investigate the insulation failure of silicone gel materials under an ultra-fast pulsed electric field, Marcus hopping mechanism for charge response is proposed. By calculating the relaxation time with different defects, we characterise the degradation of the materials. According to the force analysis of space charge, the authors establish a relationship between insulation failures and charge relaxation time. Combined with the experimental results on electrical treeing in silicone gel, the feasibility of the theory is verified. The experimental phenomenon can be well explained, that is, the initial voltage of the electrical trees decreased sharply with shortening the edge time of the pulsed electric field, especially on the nanosecond time scale.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1383-1392"},"PeriodicalIF":4.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12484","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143253474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of accelerator on properties of epoxy resin re-prepared from alcoholysis recycling","authors":"Xin Zhao, Wendong Li, Xiong Yang, Wenrui Li, Fangzheng Zou, Wang Guo, Guanjun Zhang","doi":"10.1049/hve2.12481","DOIUrl":"10.1049/hve2.12481","url":null,"abstract":"<p>Alcoholysis has emerged as a crucial method for the degradation of anhydride-cured epoxy resin, and the degraded epoxy resin (DER) can be reused to prepare a new resin. Accelerator is commonly employed in the preparation of epoxy resin to expedite the curing process. However, the effect of accelerator content on the re-prepared resin's performance has remained unexplored. Hence, DER is used to replace part bisphenol A diglycidyl ether to prepare new resins with varying accelerator contents, and the comprehensive properties of new resins are investigated. The results demonstrate that the accelerator-free re-prepared resin exhibits a performance that is comparable to that of the original resin. After accelerator is added during the preparation of new resins, the curing temperature of the reconstituted resin shows a decrease, and two peaks appear during the curing exothermic process. Besides, as the accelerator content increases, the insulation performance initially improves and then deteriorates, while the mechanical and thermal properties continue to decline. Through characterisation and chemical simulation analysis, it is believed that excessive accelerators are detrimental to the cross-linking reaction of DER. Therefore, the accelerator content in the new epoxy resin should not be high.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"208-218"},"PeriodicalIF":4.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12481","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2024-08-26DOI: 10.1049/hve2.12448
Ji Li, Jingfeng Tang, Yuqing Lou, Haoran Zhang, Lu Wang, Tianyuan Ji, Daren Yu, Ximing Zhu
{"title":"Energy regulation of impulse current generator modulated DC arc discharge","authors":"Ji Li, Jingfeng Tang, Yuqing Lou, Haoran Zhang, Lu Wang, Tianyuan Ji, Daren Yu, Ximing Zhu","doi":"10.1049/hve2.12448","DOIUrl":"10.1049/hve2.12448","url":null,"abstract":"<p>This paper proposes a method of impulse current generator modulated DC arc by combining the advantages of pulse and the RF to solve the low electron energy problem of direct current arc. Through experimental analyzing the electrical, spectral, and optical characteristics of the arc, the effect of impulse current generator (ICG) on improving electron energy is discussed. The results show that the ICG consumes more energy to enhance the strength of arc discharge, and therefore electron energy is increased in a microsecond scale. In addition, it is found that the electron energy of the arc discharge can be adjusted by varying inductance, capacitance, and discharge tube: increasing the inductance or capacitance can increase the electron energy firstly and then decrease it. In adjusting the three adjustable components, adjusting the inductor is the most effective method, followed by adjusting the capacitor, and adjusting the repetition frequency has the least effect. The reason is discussed, and it is believed that the results are related to leakage inductance and distributed capacitance.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 5","pages":"1046-1058"},"PeriodicalIF":4.9,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12448","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2024-08-23DOI: 10.1049/hve2.12480
Tian Liang, Zhijin Zhang, Xingliang Jiang, Jianlin Hu, Qin Hu
{"title":"A method for simulating powdering of silicone rubber composite insulator in coastal areas","authors":"Tian Liang, Zhijin Zhang, Xingliang Jiang, Jianlin Hu, Qin Hu","doi":"10.1049/hve2.12480","DOIUrl":"10.1049/hve2.12480","url":null,"abstract":"<p>In recent years, the powdering phenomenon often has been found in suspension composite insulators operating in outdoor environments, and there is currently a gap in research on the composition and formation process of powdered substance. A method for simulating powdering of silicone rubber (SiR) in a high humidity salt-fog environment is proposed, and the obtained powder is compared with the natural powder. Test results show that the powder obtained from artificial environments is similar to the natural powder in coastal areas, which proves that this method is reasonable to simulate the powdering process. Powdered substances are generally composed of two types of substances, Type I is an inorganic filler and its dehydration product and Type II is a small molecular siloxane. The average particle size of artificial powder is 8–10 μm, while that of natural powder is 3–5 μm. All the dielectric properties of powdered SiR decreased, and after 12 h of ageing, the dielectric properties of the artificial sample were close to those in coastal areas, and the element composition was also similar. Aluminium hydroxide (Al(OH)<sub>3</sub>) crystals were detected in both powders. The change trend of the characteristic functional groups in the infrared spectrum of the artificial powder is consistent with that of the natural powder, but the degree of molecular chain bond destruction is lower.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1336-1346"},"PeriodicalIF":4.9,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12480","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143253226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stress grading system optimisation for an inverter-fed rotating machine","authors":"Peng Wang, Wenhuan Zhao, Yue Zhang, Shuai Yang, Andrea Cavallini, Chaofan Yu, Chizhou Cheng, Yingwei Zhu","doi":"10.1049/hve2.12478","DOIUrl":"10.1049/hve2.12478","url":null,"abstract":"<p>Stress grading systems using non-linear resistive coatings are a key component to suppress surface corona in the end-windings of rotating machine. Compared to a sinusoidal-fed motor, the high slew rate of the voltage at the flanks of the repetitive square voltages from the inverter cause large capacitive currents to flow in the main wall insulation. These large currents, if not properly considered in the design phase, lead to severe electrothermal stress of the grading system. Experiments and simulations were conducted on a stress grading system whose structure arises from limitation posed by the motor structure. Measurements performed with different rise times show that the maximum potential along the conductive armour tape (CAT) increases non-linearly with increasing axial distance, and the potential at the edge of the CAT reached nearly twice the peak-to-peak voltage at 500 ns rise time, leading to corona inception. As metal plates are used in the machine to dampen vibrations in the end-winding, similar plates were also fastened to the stress grading system, worsening the already inadequate corona suppression performance. The stress grading system was therefore modified, avoiding the surface corona while, at the same time, reducing the temperature in the grading system to acceptable levels.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 5","pages":"1115-1124"},"PeriodicalIF":4.9,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12478","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A strategy for accurate prediction of dielectric permittivity and dielectric strength in polyimide","authors":"Yu Wang, Changhai Zhang, Jiaqi Lin, Hongguo Sun, Ying Yang, Wenlong Yang","doi":"10.1049/hve2.12479","DOIUrl":"10.1049/hve2.12479","url":null,"abstract":"<p>A strategy was proposed to predict accurately the dielectric permittivity and dielectric strength based on the Onsager local field theory. The molecular dynamic simulation was utilised to analyse the dipole moment fluctuation in polyimide (PI) to reflect the polarisation response of applied electric field. The simulation results revealed that the optical dielectric permittivity and static dielectric permittivity were 2.62 and 3.34, showing that the electronic displacement polarisation of the PI acted as a major contributor. The deviation between simulated and measured values of the frequency-dependent relative dielectric permittivity was no more than 5%, which exhibited high accuracy. As the polarisation response of the polar groups in the PI was at infrared frequencies, the conductive loss may be the dominant role in 10<sup>2</sup>–10<sup>6</sup> Hz at room temperature. Moreover, the effect of Joule heat on the structure, dielectric permittivity and Young modulus was considered to accurately predict the dielectric strength of the PI (359 kV/mm), which was in agreement with experimental values in the literature. These results establish a clear correlation between structural characteristics and dielectric properties of the PI, which would be the theoretical insights into the design and synthesis of the PI with tailored dielectric properties.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1393-1401"},"PeriodicalIF":4.9,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12479","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143252979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2024-07-31DOI: 10.1049/hve2.12476
Manuel De La Hoz, Petrus Jacobus Pieterse, Agurtzane Etxegarai, Diego Gonzalez, Ángel Javier Mazon, Dirk Uhrlandt
{"title":"Comparison of corona effect prediction criteria on sphere-plane configuration","authors":"Manuel De La Hoz, Petrus Jacobus Pieterse, Agurtzane Etxegarai, Diego Gonzalez, Ángel Javier Mazon, Dirk Uhrlandt","doi":"10.1049/hve2.12476","DOIUrl":"10.1049/hve2.12476","url":null,"abstract":"<p>When designing high-voltage elements, knowing if the corona effect will be present during their life cycle is relevant. Therefore, designers consider several prediction criteria based on physical features related to breakdown discharge principles to predict the corona effect. The introduced practical set-up consists of a concave cone electrode with a hemispheric tip above a plate to evaluate selected corona prediction criteria. The hemisphere has a fixed diameter of 7 mm, and the electrode separation ranges from 2.5 to 39 cm. Information about the corona mode inception under different voltage sources was extracted using an intensified charge-coupled device camera and a partial discharge metre. The prediction criteria were connected to a specific corona mode depending on the main discharge structure behind its development. The average deviation between these criteria and experimental results was around eight percent. Underlying assumptions in criteria are also discussed in light of the experimental results.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 4","pages":"957-969"},"PeriodicalIF":4.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12476","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2024-07-30DOI: 10.1049/hve2.12475
Giovanni Gardan, Gian Carlo Montanari
{"title":"AC ripple on DC voltage: Experimental and theoretical investigation of the impact on accelerated ageing in electrical insulation","authors":"Giovanni Gardan, Gian Carlo Montanari","doi":"10.1049/hve2.12475","DOIUrl":"10.1049/hve2.12475","url":null,"abstract":"<p>With the increasing penetration of DC systems into the high voltage and medium voltage power industry, DC voltage is becoming common for distribution/transmission and to supply different typologies of loads. The allowable extent of AC ripple superimposed to DC, and its effect on insulation ageing, is a long-term discussed topic. The most harmful phenomenon causing extrinsic ageing acceleration and insulation system premature failure is partial discharges (PD); thus, the risk of incepting PD due to AC ripple could become a primary issue for electrical asset equipment reliability. In this work, the impact of AC sinusoidal ripple on insulation system life and reliability is dealt with, considering both intrinsic and extrinsic ageing but focusing on the latter, that is, the PD aspect. Experiments are performed to assess how the jump voltage (due to AC ripple) and the DC component impact on PD activity in terms of amplitude and repetition rate. For the first time, the correlation between the magnitude of jump voltage associated with ripple and PD inception is established, shedding a light on the allowable ripple extent which does not impact significantly on ageing and premature insulation failure. This approach can provide straightforward tools for design specification and ageing inference of insulation systems.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 4","pages":"902-910"},"PeriodicalIF":4.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12475","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ultrasonic localization method based on Chan-WLS algorithm for detecting power transformer partial discharge faults by fibre optic F-P sensing array","authors":"Hong Liu, Tianhe Yang, Zhixian Zhang, Haoyuan Tian, Yuxuan Song, Qiuxia Sun, Wei Wang, Yunjun Geng, Weigen Chen","doi":"10.1049/hve2.12472","DOIUrl":"10.1049/hve2.12472","url":null,"abstract":"<p>Fibre optic F-P sensor has become one of the mainstream detection methods for partial discharge faults due to their advantages of good insulation, high sensitivity, resistance to electromagnetic interference, simple structure and inexpensive pricing. The first-order resonant frequency of the acoustically sensitive diaphragm of the F-P sensor is given based on the theory of plate and shell vibration, and the fibre optic F-P sensing array is designed based on the Fabry–Perot interference principle. A sensor installation method is also proposed for introducing a fibre optic F-P probe into the power transformer interior using a fibre optic penetrator through flange at the power transformer oil change valve. A system of non-linear equations is developed by utilising the time difference of arrival (TDOA) of the partial discharge ultrasound signal propagation to the F-P sensing array. The Chan-WLS algorithm is used to convert the non-linear equations in the TDOA localisation method into a non-linear optimisation problem to be solved and experimentally verified on the 220 kV real power transformer. The experimental results show that the error in the partial discharge fault localisation is solved based on the Chan-WLS algorithm and the actual location is 20.27 cm, which is within the acceptable error.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1234-1245"},"PeriodicalIF":4.9,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12472","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141822932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2024-07-15DOI: 10.1049/hve2.12465
Shijie Huang, Haiqing Niu
{"title":"Modular digital twin modelling method for 10 kV cable lines based on real-time temperature field inversion","authors":"Shijie Huang, Haiqing Niu","doi":"10.1049/hve2.12465","DOIUrl":"10.1049/hve2.12465","url":null,"abstract":"<p>State perception of long-span 10 kV cable lines is one of the critical issues in building intelligent distribution networks. Digital twin (DT), which can map the physical status of equipment in real-time, has received extensive attention. However, traditional modelling methods cannot meet the requirement of long-span complex DT's real-time computation and scalability. In order to reduce the modelling cost and improve the calculation speed, a modular DT modelling method for cable lines based on real-time temperature field inversion is proposed. The authors develop a modular reduced-order modelling method that applies to long-span 10 kV cable lines. Combined with the temperature field inversion, a DT inversion algorithm is proposed to evaluate the transient temperature field and contact resistance inside cable lines, which has been used to evaluate the emergency load capacity. Finally, temperature rise tests verified the DT inversion algorithm's correctness. The operating status of cable lines was evaluated through the modular DT, and the emergency time and emergency ampacity were calculated. The result shows that the new method meets the real-time and high-precision requirements of DT calculation in actual operation scenarios. It can be easily extended to cable lines of different voltage levels.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"56-68"},"PeriodicalIF":4.9,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}