Pub Date : 2019-06-01DOI: 10.1109/EIC43217.2019.9046635
J. Slater, I. Mitiche, A. Nesbitt, G. Morison, P. Boreham
On-line condition monitoring of substation electrical equipment depends on reliable, non-invasive surveillance techniques. Early detection of faults helps to mitigate the need for reactive maintenance and unplanned system downtime, thus ensuring continuity of supply. The Electro Magnetic Interference (EMI) method is a surveillance technique that can assist in identifying insulation degradation and conductor faults; such as Partial Discharge (PD) and Arcing. EMI frequency scans are used to identify the frequencies that are characteristic of fault conditions. Time-resolved analysis at these frequencies provides crucial data necessary for the classification of these faults. With the emergence of continuous on-line monitoring, there is an increasing need to embed more intelligence within monitoring devices to automatically recognise developing fault conditions. The main challenges faced with this method is that there is too much emphasis put on engineers in the field being able to identify these key frequencies by eye or knowledge alone, which limits the ability to automate the process. This paper presents a novel diagnostic assistant that will automatically identify the spot frequencies the engineer would manually capture for further, time-resolved analysis. The resultant time-resolved scans are then analysed to perform feature extraction and dimensionality reduction to automatically classify the data to a known fault category. Validation of the proposed techniques has been performed on real world data captured and labelled by engineers in the field. The accuracy of this method is established through direct comparison between the choices made by the engineers in the field to the classification of fault conditions and the decisions of the automated diagnostic assistant. The consistent accuracy of the results obtained paves the way for a fully automated expert system that can identify and classify possible emerging fault conditions utilising EMI diagnostics.
{"title":"Automated identification of insulation faults using Electro Magnetic Interference methods","authors":"J. Slater, I. Mitiche, A. Nesbitt, G. Morison, P. Boreham","doi":"10.1109/EIC43217.2019.9046635","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046635","url":null,"abstract":"On-line condition monitoring of substation electrical equipment depends on reliable, non-invasive surveillance techniques. Early detection of faults helps to mitigate the need for reactive maintenance and unplanned system downtime, thus ensuring continuity of supply. The Electro Magnetic Interference (EMI) method is a surveillance technique that can assist in identifying insulation degradation and conductor faults; such as Partial Discharge (PD) and Arcing. EMI frequency scans are used to identify the frequencies that are characteristic of fault conditions. Time-resolved analysis at these frequencies provides crucial data necessary for the classification of these faults. With the emergence of continuous on-line monitoring, there is an increasing need to embed more intelligence within monitoring devices to automatically recognise developing fault conditions. The main challenges faced with this method is that there is too much emphasis put on engineers in the field being able to identify these key frequencies by eye or knowledge alone, which limits the ability to automate the process. This paper presents a novel diagnostic assistant that will automatically identify the spot frequencies the engineer would manually capture for further, time-resolved analysis. The resultant time-resolved scans are then analysed to perform feature extraction and dimensionality reduction to automatically classify the data to a known fault category. Validation of the proposed techniques has been performed on real world data captured and labelled by engineers in the field. The accuracy of this method is established through direct comparison between the choices made by the engineers in the field to the classification of fault conditions and the decisions of the automated diagnostic assistant. The consistent accuracy of the results obtained paves the way for a fully automated expert system that can identify and classify possible emerging fault conditions utilising EMI diagnostics.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123164877","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046534
Alireza Naeini, E. Cherney, S. Jayaram
Surface partial discharges on the stress grading system of a medium voltage form-wound coil fed by an inverter can lead to insulation failure. Reducing the maximum surface electric field is therefore essential for prolonging insulation life. Under square waves in simulations using COMSOL Multiphysics, this work studies how floating metal foils added to the stress grading tape (SGT) affect electric field and temperature distributions. The results show that the metal foils make the electric field uniform but increase the temperature, due to increased current density in the stress grading tape. However, the temperature rise is below that considered to be detrimental to the insulation.
{"title":"A New Approach to Make the Electric Field Uniform Along the Stress Grading System of A Form-Wound Coil under Square Waves","authors":"Alireza Naeini, E. Cherney, S. Jayaram","doi":"10.1109/EIC43217.2019.9046534","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046534","url":null,"abstract":"Surface partial discharges on the stress grading system of a medium voltage form-wound coil fed by an inverter can lead to insulation failure. Reducing the maximum surface electric field is therefore essential for prolonging insulation life. Under square waves in simulations using COMSOL Multiphysics, this work studies how floating metal foils added to the stress grading tape (SGT) affect electric field and temperature distributions. The results show that the metal foils make the electric field uniform but increase the temperature, due to increased current density in the stress grading tape. However, the temperature rise is below that considered to be detrimental to the insulation.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121072189","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046532
Han Xiong, R. Liu, Boxue Hu, Haoyang You, Zhuo Wei, Julia Zhang, Jin Wang
Unexpected premature insulation breakdown has been reported for many electric machines driven by variable speed drives (VSDs). A major cause is the reflected voltage overshoots at the machine winding caused by the pulse voltage excitation, leading to severe stress on the insulation system. At The Ohio State University (OSU), we have started a series of efforts to understand the degradation and breakdown of the insulation systems in electric machines driven by VSDs. This paper reports our activities on partial discharge (PD) detection and characterization for random-wound low voltage and form-wound medium voltage coils excited by PWM voltages. A PD detection platform has been established consisting of three main systems: the testing samples and setups, the pulsed voltage generation system, and the PD detection system. One silicon (Si) based and two silicon-carbide (SiC) based pulsed voltage generators were employed to produce voltage excitations with a magnitude up to 10 kV and a $dV/dt$ up to $mathbf{70 kV}/mumathbf{s}$. The PD detection system, moreover, installed nine sensors catering to five different physical manifestations during PD: electrical current, electromagnetic wave, optical light emission, acoustic ultrasound emission and chemical ozone emission. The detection effectiveness of each type of sensor is presented and compared using twisted pairs of magnet wire samples. The demonstrated results hope to provide a better understanding of the effect of VSDs on the behaviors of PDs in electric machine winding insulation systems, and also some insight for the selection and evaluation of PD detectors for various VSD applications.
{"title":"The Ohio State University Partial Discharge Detection Platform for Electric Machine Windings Driven by PWM Voltage Excitation","authors":"Han Xiong, R. Liu, Boxue Hu, Haoyang You, Zhuo Wei, Julia Zhang, Jin Wang","doi":"10.1109/EIC43217.2019.9046532","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046532","url":null,"abstract":"Unexpected premature insulation breakdown has been reported for many electric machines driven by variable speed drives (VSDs). A major cause is the reflected voltage overshoots at the machine winding caused by the pulse voltage excitation, leading to severe stress on the insulation system. At The Ohio State University (OSU), we have started a series of efforts to understand the degradation and breakdown of the insulation systems in electric machines driven by VSDs. This paper reports our activities on partial discharge (PD) detection and characterization for random-wound low voltage and form-wound medium voltage coils excited by PWM voltages. A PD detection platform has been established consisting of three main systems: the testing samples and setups, the pulsed voltage generation system, and the PD detection system. One silicon (Si) based and two silicon-carbide (SiC) based pulsed voltage generators were employed to produce voltage excitations with a magnitude up to 10 kV and a $dV/dt$ up to $mathbf{70 kV}/mumathbf{s}$. The PD detection system, moreover, installed nine sensors catering to five different physical manifestations during PD: electrical current, electromagnetic wave, optical light emission, acoustic ultrasound emission and chemical ozone emission. The detection effectiveness of each type of sensor is presented and compared using twisted pairs of magnet wire samples. The demonstrated results hope to provide a better understanding of the effect of VSDs on the behaviors of PDs in electric machine winding insulation systems, and also some insight for the selection and evaluation of PD detectors for various VSD applications.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127502223","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046541
M. Borghei, M. Ghassemi
This paper develops a revolutionary design for transmission lines by shifting phase configurations and sub-conductors into unconventional arrangements that are geometrically optimized, leading to very high surge impedance loading (HSIL) and very low corridor width (CW) (ultra SIL/CW).
{"title":"Geometrically Optimized Phase Configurations and Sub-conductors in the Bundle for Power Transmission Efficiency","authors":"M. Borghei, M. Ghassemi","doi":"10.1109/EIC43217.2019.9046541","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046541","url":null,"abstract":"This paper develops a revolutionary design for transmission lines by shifting phase configurations and sub-conductors into unconventional arrangements that are geometrically optimized, leading to very high surge impedance loading (HSIL) and very low corridor width (CW) (ultra SIL/CW).","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126621326","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046610
A. Naderian, Pranav Pattabi, L. Lamarre
A significant number of power transformers worldwide are displaying an ever-increasing trend of unreliable operation and shortened lifetimes, due to poor electrical or mechanical conditions and onerous loading situations. Monitoring the condition of these transformers and accurately predicting their useful remaining life is quite significant to utilities and/or independent owners especially considering the high replacement cost and criticality associated with the smooth functioning of these assets. In this regard, the condition of the insulation system plays a pivotal role in influencing the remnant useful life associated with power transformers. This paper provides a better estimation for determining the remaining life of a power transformer based on the results of an improved dynamic model. The model is an upgrade over the basic life expectancy formulation provided by existing IEEE and IEC standards in this domain and considers parameters such as hotspot temperature, moisture, oxygen, the ratio of carbon oxides (CO2/CO), the degree of polymerization (DP) and the concentration of furfural (2-FAL) or methanol (MeOH) as aging markers.
{"title":"Improving the Assessment of Remaining Life of Service Aged Power Transformers","authors":"A. Naderian, Pranav Pattabi, L. Lamarre","doi":"10.1109/EIC43217.2019.9046610","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046610","url":null,"abstract":"A significant number of power transformers worldwide are displaying an ever-increasing trend of unreliable operation and shortened lifetimes, due to poor electrical or mechanical conditions and onerous loading situations. Monitoring the condition of these transformers and accurately predicting their useful remaining life is quite significant to utilities and/or independent owners especially considering the high replacement cost and criticality associated with the smooth functioning of these assets. In this regard, the condition of the insulation system plays a pivotal role in influencing the remnant useful life associated with power transformers. This paper provides a better estimation for determining the remaining life of a power transformer based on the results of an improved dynamic model. The model is an upgrade over the basic life expectancy formulation provided by existing IEEE and IEC standards in this domain and considers parameters such as hotspot temperature, moisture, oxygen, the ratio of carbon oxides (CO2/CO), the degree of polymerization (DP) and the concentration of furfural (2-FAL) or methanol (MeOH) as aging markers.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127420661","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046577
Ouassim Agri, J. Augé, E. Vagnon, F. Buret
This paper studies the breakdown voltage for different insulating materials encapsulating power electronic devices. A comparison between some liquids and silicone gel is carried out. The 50 Hz AC voltage tests were performed according to the IEC 60156 specifications. The same process was applied to the DC voltage tests due to a lack of standard procedure concerning DC voltage tests on liquids. In each case, a ceramic substrate was placed in a container filled with the insulating material. A voltage was applied between two electrodes glued on the substrate. Mineral, both synthetic and natural ester oils and silicone gel were tested. The voltages of breakdown between oils were quite similar in AC and DC. The gel is more resistant to DC stress even though its self-healing is less than the liquids investigated.
{"title":"Insulating Liquids, an Alternative to Silicone Gel for Power Electronic Devices","authors":"Ouassim Agri, J. Augé, E. Vagnon, F. Buret","doi":"10.1109/EIC43217.2019.9046577","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046577","url":null,"abstract":"This paper studies the breakdown voltage for different insulating materials encapsulating power electronic devices. A comparison between some liquids and silicone gel is carried out. The 50 Hz AC voltage tests were performed according to the IEC 60156 specifications. The same process was applied to the DC voltage tests due to a lack of standard procedure concerning DC voltage tests on liquids. In each case, a ceramic substrate was placed in a container filled with the insulating material. A voltage was applied between two electrodes glued on the substrate. Mineral, both synthetic and natural ester oils and silicone gel were tested. The voltages of breakdown between oils were quite similar in AC and DC. The gel is more resistant to DC stress even though its self-healing is less than the liquids investigated.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121823802","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046570
J. Villibor, E. W. Neto, G. Lopes, G. Faria, Matheus Pereira, T. Nogueira, P. Tavares
This paper aims to analyze, technically and economically, the benefits of the copper utilization on new windings of repaired distribution transformers, originally designed for aluminum. Three commercial single-phase distribution transformers commonly installed on urban and countryside areas of Brazil were submitted to routine tests and temperature rise test. All the tests were performed at LAT-EFEI- High Voltage Laboratory in accordance to Brazilian standards and the Brazilian Labeling Program (PBE) for oil-immersed distribution transformers. The technical evaluation compares the losses before and after the repair process and the temperature rise test results of the repaired transformers. The economic analysis is based on load losses and no-load losses capitalization along the equipment useful lifetime and compares the investment in a repaired level C transformer, made with copper, against level E transformer, made with aluminum, providing the net present value and the investment payback time.
{"title":"Technical and economic analysis of copper utilization on new windings of repaired distribution transformers originally designed for aluminum","authors":"J. Villibor, E. W. Neto, G. Lopes, G. Faria, Matheus Pereira, T. Nogueira, P. Tavares","doi":"10.1109/EIC43217.2019.9046570","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046570","url":null,"abstract":"This paper aims to analyze, technically and economically, the benefits of the copper utilization on new windings of repaired distribution transformers, originally designed for aluminum. Three commercial single-phase distribution transformers commonly installed on urban and countryside areas of Brazil were submitted to routine tests and temperature rise test. All the tests were performed at LAT-EFEI- High Voltage Laboratory in accordance to Brazilian standards and the Brazilian Labeling Program (PBE) for oil-immersed distribution transformers. The technical evaluation compares the losses before and after the repair process and the temperature rise test results of the repaired transformers. The economic analysis is based on load losses and no-load losses capitalization along the equipment useful lifetime and compares the investment in a repaired level C transformer, made with copper, against level E transformer, made with aluminum, providing the net present value and the investment payback time.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130695077","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}
In recent years, due to the high concentration of solid particles in transformer insulating oil, some large power transformers domestic and abroad have caused insulation fault. The influence of metal particles on the breakdown voltage of transformer oil is self-evident, relevant research shows that the damage of metal particles to the insulation performance of transformer oil is much higher than that of non-metallic particles such as cellulose particles. In this paper, a discharge test tank was designed and manufactured, and a lightning impulse discharge test platform for oil-paper insulation was built based on shadow imaging principle. The preparation method of insulating oil sample containing fixed metal particle concentration was put forward, a streamer development characteristic test scheme had been worked out. The effect of copper particles on the discharge characteristics of oil-impregnated insulating paper under two different field arrangement was studied. Discharge streamer imaging experiments of two insulating paper models were carried out under pre-breakdown voltage, and the streamer morphology characteristics were compared with the pure oil gap. When the insulating paper is placed along field lines, the streamer tends to develop along the surface of the insulating paper as a whole, and the insulating paper will speed up the development of streamer in oil. When the insulating paper is placed perpendicular to field lines, the paper will not affect the development of the streamer between the oil gaps, but will prevent the final formation of the main discharge channel of the streamer.
{"title":"Influence of Pressboard Orientation in the Electric Field on Lightning Impulse Discharge Characteristics of Oil-Pressboard Insulation","authors":"Jiansheng Li, Chao Wei, Yiming Wu, Shengquan Wang, Yuandi Lin, Leifeng Huang, Houying Li, Youyuan Wang","doi":"10.1109/EIC43217.2019.9046578","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046578","url":null,"abstract":"In recent years, due to the high concentration of solid particles in transformer insulating oil, some large power transformers domestic and abroad have caused insulation fault. The influence of metal particles on the breakdown voltage of transformer oil is self-evident, relevant research shows that the damage of metal particles to the insulation performance of transformer oil is much higher than that of non-metallic particles such as cellulose particles. In this paper, a discharge test tank was designed and manufactured, and a lightning impulse discharge test platform for oil-paper insulation was built based on shadow imaging principle. The preparation method of insulating oil sample containing fixed metal particle concentration was put forward, a streamer development characteristic test scheme had been worked out. The effect of copper particles on the discharge characteristics of oil-impregnated insulating paper under two different field arrangement was studied. Discharge streamer imaging experiments of two insulating paper models were carried out under pre-breakdown voltage, and the streamer morphology characteristics were compared with the pure oil gap. When the insulating paper is placed along field lines, the streamer tends to develop along the surface of the insulating paper as a whole, and the insulating paper will speed up the development of streamer in oil. When the insulating paper is placed perpendicular to field lines, the paper will not affect the development of the streamer between the oil gaps, but will prevent the final formation of the main discharge channel of the streamer.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133331531","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}
Different from conventional three-phase asynchronous motor working at sinusoidal voltages, the inverter-fed motors are stressed by high frequency semi-square wave voltages generated by inverters. Due to the over-voltages at the motor terminals and the voltage uneven distribution in winding, the electrical field in insulation may reach partial discharge inception voltage (PDIV) and PD will occur with high probability. For the insulation systems of Type II motors, whose insulation is composed of corona-resistance materials, moderate PD activities are allowed. The endurance (lifetime) tests, however, under repetitive impulsive voltages should be carried out to evaluate the insulation performance. One of the problems needed to be solved for the endurance tests at impulsive voltages is how to design a reliable breakdown protection circuit used to remove the samples (in several microseconds) from the whole system when breakdown occurs and record the endurance time. Conventional over-current hardware used under AC and DC voltages cannot be used anymore because the peak magnitude of the normal charging and discharging current at rising and falling flanks of impulsive voltages and the breakdown current are similar. This paper aims to report a novel breakdown protection circuit specially designed for the endurance tests at impulsive voltages. The current at impulsive voltages will be measured by HALL sensors and processed by FPGA in real time to distinguish the possible breakdown current from the normal charging-discharging current and responds to the generator in several micro-seconds when breakdown occurs.
{"title":"A Novel Breakdown Protection Circuit for Endurance Tests under Repetitive Impulsive Voltages","authors":"Peng Wang, Yanghao Gu, Qi Wu, A. Cavallini, Qin Zhang, Jiawei Zhang","doi":"10.1109/EIC43217.2019.9046595","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046595","url":null,"abstract":"Different from conventional three-phase asynchronous motor working at sinusoidal voltages, the inverter-fed motors are stressed by high frequency semi-square wave voltages generated by inverters. Due to the over-voltages at the motor terminals and the voltage uneven distribution in winding, the electrical field in insulation may reach partial discharge inception voltage (PDIV) and PD will occur with high probability. For the insulation systems of Type II motors, whose insulation is composed of corona-resistance materials, moderate PD activities are allowed. The endurance (lifetime) tests, however, under repetitive impulsive voltages should be carried out to evaluate the insulation performance. One of the problems needed to be solved for the endurance tests at impulsive voltages is how to design a reliable breakdown protection circuit used to remove the samples (in several microseconds) from the whole system when breakdown occurs and record the endurance time. Conventional over-current hardware used under AC and DC voltages cannot be used anymore because the peak magnitude of the normal charging and discharging current at rising and falling flanks of impulsive voltages and the breakdown current are similar. This paper aims to report a novel breakdown protection circuit specially designed for the endurance tests at impulsive voltages. The current at impulsive voltages will be measured by HALL sensors and processed by FPGA in real time to distinguish the possible breakdown current from the normal charging-discharging current and responds to the generator in several micro-seconds when breakdown occurs.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128817006","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046583
Atip Doolgindachbaporn, N. H. Nik Ali, G. Callender, J. Pilgrim, P. Lewin, G. Wilson
In this paper, time series decomposition and thermal models are used to identify WTI issues; specifically an absence of sensor load dependency and detecting when the WTI is tracking top oil. Following this, two different transformer thermal models are used to calculate WTI temperatures which are then compared to WTI measurements under forced-cooling conditions to identify cooling issues, especially a reduction in cooling performance. A discussion of the differences between two different transformer thermal models, IEC 60076–7 and one purposed by Susa, is provided.
{"title":"Detection of Forced Cooling Faults in Power Transformers based on Winding Temperature Indicator and Load Data","authors":"Atip Doolgindachbaporn, N. H. Nik Ali, G. Callender, J. Pilgrim, P. Lewin, G. Wilson","doi":"10.1109/EIC43217.2019.9046583","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046583","url":null,"abstract":"In this paper, time series decomposition and thermal models are used to identify WTI issues; specifically an absence of sensor load dependency and detecting when the WTI is tracking top oil. Following this, two different transformer thermal models are used to calculate WTI temperatures which are then compared to WTI measurements under forced-cooling conditions to identify cooling issues, especially a reduction in cooling performance. A discussion of the differences between two different transformer thermal models, IEC 60076–7 and one purposed by Susa, is provided.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129042761","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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