Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509123
L. Cheng, G. Bo, Li Xiaonan, Liu Kai, Yang Yan
High-frequency transformers with small size and light weight have been widely concerned by researchers at home and abroad. The oil-paper insulation of high frequency transformers is affected by the high frequency pulse produced by power electronic device, which is more prone to discharge fault and insulation failure. To study the effect of high frequency pulse voltage on the discharge characteristics of oil-paper insulation, a needle plate electrode model was used to carry out the discharge experiment of different layers of oil-paper insulation samples at 1–20 kHz bipolar high frequency square wave voltage produced by high frequency power supply. The partial discharge and breakdown characteristics of oil-paper insulation under high frequency square wave pulse voltage were studied. The results show that the discharge quantity of oilpaper insulation increases greatly with high frequency pulse voltage compared with AC voltage. There is no discharge phenomenon in the process of discharge development, which is significantly different from that under AC voltage. The intensity of discharge increases under high frequency pulse voltage and its increasement accelerates the deterioration of oil-paper insulation.
{"title":"Study on Discharge Characteristics of Multilayer Oil-paper under High Frequency Pulse Voltage","authors":"L. Cheng, G. Bo, Li Xiaonan, Liu Kai, Yang Yan","doi":"10.1109/ICEMPE51623.2021.9509123","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509123","url":null,"abstract":"High-frequency transformers with small size and light weight have been widely concerned by researchers at home and abroad. The oil-paper insulation of high frequency transformers is affected by the high frequency pulse produced by power electronic device, which is more prone to discharge fault and insulation failure. To study the effect of high frequency pulse voltage on the discharge characteristics of oil-paper insulation, a needle plate electrode model was used to carry out the discharge experiment of different layers of oil-paper insulation samples at 1–20 kHz bipolar high frequency square wave voltage produced by high frequency power supply. The partial discharge and breakdown characteristics of oil-paper insulation under high frequency square wave pulse voltage were studied. The results show that the discharge quantity of oilpaper insulation increases greatly with high frequency pulse voltage compared with AC voltage. There is no discharge phenomenon in the process of discharge development, which is significantly different from that under AC voltage. The intensity of discharge increases under high frequency pulse voltage and its increasement accelerates the deterioration of oil-paper insulation.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"1 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76835492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509222
Ziru Zha, Senkun Mei, Zhipeng Zhou, Zhenxing Wang, Zhiyuan Liu
Vacuum trigger switch is a widely used equipment in a wide voltage range, and recently researchers cover the conventional metal contacts with two-dimensional material trying to enhance the performance of the trigger switch. However, the characteristic and the mechanism of the field emission from metal-substrate two-dimensional material haven't been researched precisely. Besides, an agreement has not been reached whether the emission process of two-dimensional material follows the traditional Fowler-Nordheim theory or Murphy-Good theory or not. Confronted with these problems, we established an experimental system which can measure the current as low as Pico ampere. Furthermore, Advanced Performance Detector (PHOTONIS) which is composed of a high-gain microchannel plate connected with a phosphor screen is also used to capture the electron emission image to reveal the feature of emission process before breakdown. The results show that there exists a step effect in the V-I curve of the emission process of graphene which deviates from the FN theory. Besides, a hysteresis effect also occurs in the V-I characteristic of graphene. In order to illustrate this phenomenon, we proposed a qualitative model that the free electrons are first transferred to the $mathrm{p}_{mathrm{z}}$ orbital of carbon atom of graphene from metal substrate under the applied voltage. And with the applied voltage increasing, electrons will be released to the vacuum after the $mathrm{p}_{mathrm{z}}$ orbital of the carbon atom is all filled. This model explains the step effect pretty well but is invalid for hysteresis effect and thus need to be further improved. And we believed that our model and experimental results are surely to be helpful for later researchers and to enhance the performance of the vacuum trigger switch in the future.
{"title":"Research on the Characteristic and Mechanism of Field Emission from Metal-Substrate Graphene Contact","authors":"Ziru Zha, Senkun Mei, Zhipeng Zhou, Zhenxing Wang, Zhiyuan Liu","doi":"10.1109/ICEMPE51623.2021.9509222","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509222","url":null,"abstract":"Vacuum trigger switch is a widely used equipment in a wide voltage range, and recently researchers cover the conventional metal contacts with two-dimensional material trying to enhance the performance of the trigger switch. However, the characteristic and the mechanism of the field emission from metal-substrate two-dimensional material haven't been researched precisely. Besides, an agreement has not been reached whether the emission process of two-dimensional material follows the traditional Fowler-Nordheim theory or Murphy-Good theory or not. Confronted with these problems, we established an experimental system which can measure the current as low as Pico ampere. Furthermore, Advanced Performance Detector (PHOTONIS) which is composed of a high-gain microchannel plate connected with a phosphor screen is also used to capture the electron emission image to reveal the feature of emission process before breakdown. The results show that there exists a step effect in the V-I curve of the emission process of graphene which deviates from the FN theory. Besides, a hysteresis effect also occurs in the V-I characteristic of graphene. In order to illustrate this phenomenon, we proposed a qualitative model that the free electrons are first transferred to the $mathrm{p}_{mathrm{z}}$ orbital of carbon atom of graphene from metal substrate under the applied voltage. And with the applied voltage increasing, electrons will be released to the vacuum after the $mathrm{p}_{mathrm{z}}$ orbital of the carbon atom is all filled. This model explains the step effect pretty well but is invalid for hysteresis effect and thus need to be further improved. And we believed that our model and experimental results are surely to be helpful for later researchers and to enhance the performance of the vacuum trigger switch in the future.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"1 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76050513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509062
Li Jin, Zhu Xinhan, Wang Qiang, Zhang Zhijin, J. Xingliang
The average altitude of Qinghai Tibet railway is 4000m. The correct and reasonable design of air gap of electrical insulation is the technical bottleneck to determine the clearance height of Qinghai Tibet railway tunnel and the design of overhead contact system insulation structure. However, it costs a lot to carry out the typical air gap true type test in the actual site with an average altitude of 4000m and above. Therefore, it is necessary to establish tunnel model by using the large-scale multi-functional artificial climate chamber of Chongqing University, to test and study the insulation characteristics of typical air gap under different applied voltages. According to the actual parameters of the tunnel, the stainless steel ceiling is built. Since the Golmud - Lhasa section of Qinghai Tibet railway is in single line operation, the vertical plane where the highest line of ceiling is located is taken as the measurement datum of catenary. The constant voltage rise and fall method and uniform voltage rise method recommended by IEC60507, GB / t4585, DL / t859 and other standards are used to test the breakdown characteristics of air gap. The 50% breakdown voltage under lightning impulse voltage is obtained by constant voltage rise and fall method, and the breakdown voltage under AC power supply is obtained by uniform voltage rise method. The altitude parameters are classified according to 500m, and the atmospheric parameters of 3500∼5500m are simulated. The altitude correction methods based on (d, P, h) and (d, $delta$, h) are respectively used to fit the test data to obtain the lightning impulse discharge voltage correction formula of the air insulation gap. The test results show that the error between the calculation results and the test results is less than 5.0%, which means that the test and fitting meet the engineering requirements. The calculation results show that: (1) The lightning impulse voltage of the air gap at high altitude is a function of air pressure, temperature and absolute humidity. (2) Taking the gap distance of 1000m above sea level as the reference value (di), in order to maintain the same electrical strength, a correction factor should be added to check the gap distance (dH) at high altitude.
{"title":"Study on the Lightning Strike Discharge Characteristics of Air Gap at Low Air Pressure Condition","authors":"Li Jin, Zhu Xinhan, Wang Qiang, Zhang Zhijin, J. Xingliang","doi":"10.1109/ICEMPE51623.2021.9509062","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509062","url":null,"abstract":"The average altitude of Qinghai Tibet railway is 4000m. The correct and reasonable design of air gap of electrical insulation is the technical bottleneck to determine the clearance height of Qinghai Tibet railway tunnel and the design of overhead contact system insulation structure. However, it costs a lot to carry out the typical air gap true type test in the actual site with an average altitude of 4000m and above. Therefore, it is necessary to establish tunnel model by using the large-scale multi-functional artificial climate chamber of Chongqing University, to test and study the insulation characteristics of typical air gap under different applied voltages. According to the actual parameters of the tunnel, the stainless steel ceiling is built. Since the Golmud - Lhasa section of Qinghai Tibet railway is in single line operation, the vertical plane where the highest line of ceiling is located is taken as the measurement datum of catenary. The constant voltage rise and fall method and uniform voltage rise method recommended by IEC60507, GB / t4585, DL / t859 and other standards are used to test the breakdown characteristics of air gap. The 50% breakdown voltage under lightning impulse voltage is obtained by constant voltage rise and fall method, and the breakdown voltage under AC power supply is obtained by uniform voltage rise method. The altitude parameters are classified according to 500m, and the atmospheric parameters of 3500∼5500m are simulated. The altitude correction methods based on (d, P, h) and (d, $delta$, h) are respectively used to fit the test data to obtain the lightning impulse discharge voltage correction formula of the air insulation gap. The test results show that the error between the calculation results and the test results is less than 5.0%, which means that the test and fitting meet the engineering requirements. The calculation results show that: (1) The lightning impulse voltage of the air gap at high altitude is a function of air pressure, temperature and absolute humidity. (2) Taking the gap distance of 1000m above sea level as the reference value (di), in order to maintain the same electrical strength, a correction factor should be added to check the gap distance (dH) at high altitude.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"341 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76395063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509215
Muye Zhang, Renfei Che, Jiahui Chen
In order to improve the accuracy of cable fault location, this paper proposes the principle of traveling wave fault location based on high-frequency signal real-time sensing. Use ATP-EMTP to build a cable line model, monitor fault high-frequency signals through high-frequency sensors at both ends of the line, and use wavelet transform to perform singularity detection and data analysis in Matlab. In order to reduce the effects of attenuation and dispersion in the process of traveling wave transmission, this paper proposes the concept of correction wave. First carry out a rough distance measurement of the fault, then correct the wave speed and the time for the traveling wave head to reach both ends of the line, and finally achieve precise positioning through a second distance measurement after correction. Research shows that this method can calculate the wave speed online in real time, and is not affected by the location of the fault, the fault type and the transition resistance. What's more, it improves the reliability of the positioning results.
{"title":"Traveling Wave Location of Cable Faults Based on Real-time Sensing of High Frequency Signals","authors":"Muye Zhang, Renfei Che, Jiahui Chen","doi":"10.1109/ICEMPE51623.2021.9509215","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509215","url":null,"abstract":"In order to improve the accuracy of cable fault location, this paper proposes the principle of traveling wave fault location based on high-frequency signal real-time sensing. Use ATP-EMTP to build a cable line model, monitor fault high-frequency signals through high-frequency sensors at both ends of the line, and use wavelet transform to perform singularity detection and data analysis in Matlab. In order to reduce the effects of attenuation and dispersion in the process of traveling wave transmission, this paper proposes the concept of correction wave. First carry out a rough distance measurement of the fault, then correct the wave speed and the time for the traveling wave head to reach both ends of the line, and finally achieve precise positioning through a second distance measurement after correction. Research shows that this method can calculate the wave speed online in real time, and is not affected by the location of the fault, the fault type and the transition resistance. What's more, it improves the reliability of the positioning results.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"82 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74178948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509105
M. Fan, S. Zhou, Zhonglei Li, B. Du, Fan Yu, Hong‐Da Yan
Polypropylene (PP) as a thermoplastic cable insulation material has the advantage of higher working temperature, better insulation performance and recyclability than traditional cross-linked polyethylene (XLPE). This work focuses on the effects of isothermal crystallization (IC) of PP on its electrical properties. PP with different IC time is prepared and their crystallization morphology is characterized by polarized optical microscopy (POM). The space charge distribution of the samples is measured by pulsed electro-acoustic (PEA) method, and the DC breakdown strength after the hetero-polar DC prestress of samples is carried out by the ball-plate electrode. With the IC time increasing from 0 to 10 min, the injection and accumulation of space charge is significantly inhibited. The DC breakdown strength with hetero-polar DC prestress of PP with an IC time of 10 min are both markedly higher than that of non-isothermal crystallized samples. Nevertheless, further increasing IC time to 30 min will accelerate the space charge injection and transport greatly, and the DC breakdown strength after hetero-polar DC prestress is reduced, due to large-sized spherulites. It is concluded that IC can improve the integrity of spherulites and reduce the defects in amorphous regions, thus improving the electrical performance of PP-based insulation for HVDC cables.
{"title":"Effect of Crystalline Morphology on DC-Prestressed Breakdown Characteristics of PP-based Cable Insulation","authors":"M. Fan, S. Zhou, Zhonglei Li, B. Du, Fan Yu, Hong‐Da Yan","doi":"10.1109/ICEMPE51623.2021.9509105","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509105","url":null,"abstract":"Polypropylene (PP) as a thermoplastic cable insulation material has the advantage of higher working temperature, better insulation performance and recyclability than traditional cross-linked polyethylene (XLPE). This work focuses on the effects of isothermal crystallization (IC) of PP on its electrical properties. PP with different IC time is prepared and their crystallization morphology is characterized by polarized optical microscopy (POM). The space charge distribution of the samples is measured by pulsed electro-acoustic (PEA) method, and the DC breakdown strength after the hetero-polar DC prestress of samples is carried out by the ball-plate electrode. With the IC time increasing from 0 to 10 min, the injection and accumulation of space charge is significantly inhibited. The DC breakdown strength with hetero-polar DC prestress of PP with an IC time of 10 min are both markedly higher than that of non-isothermal crystallized samples. Nevertheless, further increasing IC time to 30 min will accelerate the space charge injection and transport greatly, and the DC breakdown strength after hetero-polar DC prestress is reduced, due to large-sized spherulites. It is concluded that IC can improve the integrity of spherulites and reduce the defects in amorphous regions, thus improving the electrical performance of PP-based insulation for HVDC cables.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"11 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81625028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rapid identification of aging state of oil-paper insulation is of great significance to the operation safety of power transformers. Raman spectroscopy can rapidly analyze the aging characteristic information dissolved in oil, and it is an effective means for the aging diagnosis of oil-paper insulation. In this paper, Multiple screening KNN Algorithms for Raman spectroscopy analysis of aging oil-paper insulation samples is presented. A large number of aging oil samples were obtained by accelerated thermal aging test. According to the aging days, the samples were divided into 12 categories, and 230 Raman spectra were obtained by Raman spectroscopy. The KNN algorithm is used for classification and regression of Raman Spectra of test samples by Pearson correlation coefficient. Then, based on the traditional KNN algorithm, a multi-screening KNN is proposed according to the actual situation of the aging process of insulating oil Raman spectrum. The prediction of Multiple screening KNN Algorithms accuracy of classification reaches 87.92%, and the RMSE of regression reached 54.28.
{"title":"Aging Stage Diagnosis of Oil-Paper Insulation Equipment Using Raman Spectrum Based on Multiple screening KNN Algorithms","authors":"Yongkuo Zhou, Weigen Chen, Dingkun Yang, Ruyue Zhang","doi":"10.1109/ICEMPE51623.2021.9509179","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509179","url":null,"abstract":"Rapid identification of aging state of oil-paper insulation is of great significance to the operation safety of power transformers. Raman spectroscopy can rapidly analyze the aging characteristic information dissolved in oil, and it is an effective means for the aging diagnosis of oil-paper insulation. In this paper, Multiple screening KNN Algorithms for Raman spectroscopy analysis of aging oil-paper insulation samples is presented. A large number of aging oil samples were obtained by accelerated thermal aging test. According to the aging days, the samples were divided into 12 categories, and 230 Raman spectra were obtained by Raman spectroscopy. The KNN algorithm is used for classification and regression of Raman Spectra of test samples by Pearson correlation coefficient. Then, based on the traditional KNN algorithm, a multi-screening KNN is proposed according to the actual situation of the aging process of insulating oil Raman spectrum. The prediction of Multiple screening KNN Algorithms accuracy of classification reaches 87.92%, and the RMSE of regression reached 54.28.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"4 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84286378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By copper-alloying with different content of B element forming binary alloy to improve the bonding force between carbon and copper, and the Cu-B/sintered-carbon composites were prepared successfully by gas pressure impregnation. The mechanism of boron on interface enhancement, mechanical and electrical properties of composites was studied. The results showed that the mechanical strength and electrical conductivity were proportion to the boron content, while the contact angle was in inverse proportion to the B content. When the doping amount was 2.5wt%, the flexural strength and electrical conductivity were increased by 65% and 54% respectively compared with composites without modification and the contact angle decreased to 21°. The reason was that the boron carbide with moderate thickness at the interface could enhance the Cu/C interfacial bonding by transforming from physical bonding to chemical bonding. This study proves that the moderate addition of boron can improve the wettability of C/Cu system, which resulting in the improvement of mechanical and electrical properties of Cu-B/ sintered-carbon composites.
通过在铜中加入不同含量的B元素，形成二元合金，提高碳与铜的结合力，并通过气压浸渍法制备了Cu-B/烧结碳复合材料。研究了硼对复合材料界面增强、力学性能和电学性能的作用机理。结果表明，复合材料的机械强度和电导率与硼含量成正比，而接触角与硼含量成反比。当掺杂量为2.5wt%时，复合材料的抗弯强度和电导率分别比未改性的复合材料提高了65%和54%，接触角减小到21°。其原因是界面处厚度适中的碳化硼可以增强Cu/C界面的结合，由物理结合转变为化学结合。本研究证明，适量添加硼可以改善C/Cu体系的润湿性，从而改善Cu- b /烧结碳复合材料的力学性能和电性能。
{"title":"Improvement of Interfacial Wetting and Mechanical Electrical Properties of Cu-B/ sintered-carbon Composites","authors":"Haozi Zuo, Guangning Wu, Xiaobo Li, Zhangli Huang, Wenfu Wei, Zefeng Yang","doi":"10.1109/ICEMPE51623.2021.9509120","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509120","url":null,"abstract":"By copper-alloying with different content of B element forming binary alloy to improve the bonding force between carbon and copper, and the Cu-B/sintered-carbon composites were prepared successfully by gas pressure impregnation. The mechanism of boron on interface enhancement, mechanical and electrical properties of composites was studied. The results showed that the mechanical strength and electrical conductivity were proportion to the boron content, while the contact angle was in inverse proportion to the B content. When the doping amount was 2.5wt%, the flexural strength and electrical conductivity were increased by 65% and 54% respectively compared with composites without modification and the contact angle decreased to 21°. The reason was that the boron carbide with moderate thickness at the interface could enhance the Cu/C interfacial bonding by transforming from physical bonding to chemical bonding. This study proves that the moderate addition of boron can improve the wettability of C/Cu system, which resulting in the improvement of mechanical and electrical properties of Cu-B/ sintered-carbon composites.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"4 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85187871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509134
Wenbo Zhu, M. Fu, S. Hou, B. Hui, Yifan Zhang, B. Feng, Jun Chen, Le Gu, Huihong Huang
The oil-impregnated paper in the converter transformer, especially in the valve side bushing, is suffered by the complicated electric field. By reason of the power electronics and non-linear equipment, the oil-impregnated paper is subject to the harmonic voltages. The insulating aging is more prominent in contrast with the power transformer. Under this condition, the charges are capable to accumulate on the surface of oil-impregnated paper, which will lead to the distorting the electric field and accelerating the insulating degradation. Consequently, the performance deterioration of oil-paper insulation is inevitable. Surface fluorination is an effective approach of modifying the chemical components of polymer matrix. Hence, this paper is dedicated to research effects of thermal aging on the surface charge dynamic characteristics of fluorinated oil-paper insulation under the harmonic superimposed DC voltages. Some conclusions can be drawn that the comprehensive effect of harmonic voltage and thermal aging can significantly enhance the de-trapping of the surface charge in deep traps, the deep trap energy level density is greatly affected by the proportion of harmonic. As the thermal aging time is prolonged, the trapped charge becomes more difficult to detrap, the charge accumulation increases.
{"title":"Thermal Aging Dependent Surface Charge Characteristics of Fluorinated Oil-paper Insulation Under the Harmonic Superimposed DC Voltages","authors":"Wenbo Zhu, M. Fu, S. Hou, B. Hui, Yifan Zhang, B. Feng, Jun Chen, Le Gu, Huihong Huang","doi":"10.1109/ICEMPE51623.2021.9509134","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509134","url":null,"abstract":"The oil-impregnated paper in the converter transformer, especially in the valve side bushing, is suffered by the complicated electric field. By reason of the power electronics and non-linear equipment, the oil-impregnated paper is subject to the harmonic voltages. The insulating aging is more prominent in contrast with the power transformer. Under this condition, the charges are capable to accumulate on the surface of oil-impregnated paper, which will lead to the distorting the electric field and accelerating the insulating degradation. Consequently, the performance deterioration of oil-paper insulation is inevitable. Surface fluorination is an effective approach of modifying the chemical components of polymer matrix. Hence, this paper is dedicated to research effects of thermal aging on the surface charge dynamic characteristics of fluorinated oil-paper insulation under the harmonic superimposed DC voltages. Some conclusions can be drawn that the comprehensive effect of harmonic voltage and thermal aging can significantly enhance the de-trapping of the surface charge in deep traps, the deep trap energy level density is greatly affected by the proportion of harmonic. As the thermal aging time is prolonged, the trapped charge becomes more difficult to detrap, the charge accumulation increases.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"62 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90710698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509111
Yongguang Wang, Rongjin Huang, P. Jia, Z. Miao, Hongyu Dong, Laifeng Li
Epoxy resin (EP) with excellent electrical and mechanical properties was widely employed as the insulation structure in high-voltage (HV) power equipment. Due to its ultra-high electric field, the inevitable electrical tree aging phenomenon often occurs in the insulation materials, which seriously threatens the safe operation of power equipment. A flame retardant such as hexaphenoxy cyclotriphosphazene (HPCTP) can reduce the intensity of heat release during the thermal decomposition of epoxy groups and consume free radicals generated by the reaction of epoxy molecular chains with oxygen, which provides a potential possibility to inhibit the tree growth in the insulation materials. In this work, the electrical treeing characteristics of the HPCTP/EP composites under high electric field was studied. It's confirmed that the tree growth of HPCTP/EP composites was significantly inhibited by HPCTP. The tree initiation voltage and voltage life of the HPCTP/EP composites are both higher than those of the pure EP. The carbonization in the tree channel was effectively inhibited by HPCTP, which weakened the electric field at the tip of the tree channel, thereby prolonging the voltage life of the HPCTP/EP composites.
{"title":"Feasibility analysis of hexaphenoxy cyclotriphosphazene flame retardant for inhibiting electrical tree growth of epoxy resin","authors":"Yongguang Wang, Rongjin Huang, P. Jia, Z. Miao, Hongyu Dong, Laifeng Li","doi":"10.1109/ICEMPE51623.2021.9509111","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509111","url":null,"abstract":"Epoxy resin (EP) with excellent electrical and mechanical properties was widely employed as the insulation structure in high-voltage (HV) power equipment. Due to its ultra-high electric field, the inevitable electrical tree aging phenomenon often occurs in the insulation materials, which seriously threatens the safe operation of power equipment. A flame retardant such as hexaphenoxy cyclotriphosphazene (HPCTP) can reduce the intensity of heat release during the thermal decomposition of epoxy groups and consume free radicals generated by the reaction of epoxy molecular chains with oxygen, which provides a potential possibility to inhibit the tree growth in the insulation materials. In this work, the electrical treeing characteristics of the HPCTP/EP composites under high electric field was studied. It's confirmed that the tree growth of HPCTP/EP composites was significantly inhibited by HPCTP. The tree initiation voltage and voltage life of the HPCTP/EP composites are both higher than those of the pure EP. The carbonization in the tree channel was effectively inhibited by HPCTP, which weakened the electric field at the tip of the tree channel, thereby prolonging the voltage life of the HPCTP/EP composites.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"92 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91266537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-11DOI: 10.1109/ICEMPE51623.2021.9509067
Liangkai Wang, Kaining Hou, Xinbo Lu, Qingquan Li
Converter transformer is one of the most important equipment in DC transmission system. Its structural design is more complex than the general power transformer, and the problems of electrical insulation and local overheating are more prominent. The temperature rise will change the material properties and affect the performance of insulation. In this paper, a complete multi-physical field coupling simulation model is established, and the electric field distribution characteristics of insulation system affected by temperature gradient are analyzed. The results show that the temperature of converter transformer changes greatly, the maximum temperature rise is 62.55K, and the temperature of winding end is higher, so the coupling problem cannot be ignored. Considering the temperature gradient, the change speed of oil paper insulation field strength is accelerated, which should be paid attention to in the design of converter transformer insulation structure.
{"title":"Research on Electric Field Distribution at Winding End of Converter Transformer Considering Temperature Gradient","authors":"Liangkai Wang, Kaining Hou, Xinbo Lu, Qingquan Li","doi":"10.1109/ICEMPE51623.2021.9509067","DOIUrl":"https://doi.org/10.1109/ICEMPE51623.2021.9509067","url":null,"abstract":"Converter transformer is one of the most important equipment in DC transmission system. Its structural design is more complex than the general power transformer, and the problems of electrical insulation and local overheating are more prominent. The temperature rise will change the material properties and affect the performance of insulation. In this paper, a complete multi-physical field coupling simulation model is established, and the electric field distribution characteristics of insulation system affected by temperature gradient are analyzed. The results show that the temperature of converter transformer changes greatly, the maximum temperature rise is 62.55K, and the temperature of winding end is higher, so the coupling problem cannot be ignored. Considering the temperature gradient, the change speed of oil paper insulation field strength is accelerated, which should be paid attention to in the design of converter transformer insulation structure.","PeriodicalId":7083,"journal":{"name":"2021 International Conference on Electrical Materials and Power Equipment (ICEMPE)","volume":"11 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2021-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89737106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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