Pub Date : 2022-10-23DOI: 10.23919/arwtr54586.2022.9959958
{"title":"ARWtr 2022 Copyright Page","authors":"","doi":"10.23919/arwtr54586.2022.9959958","DOIUrl":"https://doi.org/10.23919/arwtr54586.2022.9959958","url":null,"abstract":"","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133523720","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959952
D. Robalino, L. Sosa
In this work, the authors focus on a highly-practical testing procedure bringing two main benefits to all power industry operators: a) higher confidence on the evaluation of dielectric testing, and; b) better utilization of technical and human resources. In the field, the application of dissipation factor measurements at (typically) 10 kV and at line-frequency (50 or 60 Hz) has been in use for many years without significant changes to the method. Nevertheless, multifrequency measurement of dielectric losses has opened a wider spectrum of analysis for power, distribution transformers and bushings. It is missing though, in the literature, a clear and properly supported discussion about how and when a single frequency measurement is validated with a multifrequency measurement or completely challenged. Important to recognize the link between line-frequency measurement, narrowband measurement (1 – 505 Hz) and full spectrum dielectric response (typically 1 kHz – 1 mHz). Limited information obtained in the frequency domain may identify a faulty unit but may not be used as a preventative test to minimize risk of failure. Preliminary research does address the need for limits of narrowband measurements. This is only possible when a correlation is established between temperature and frequency as it has been done using the well-known Arrhenius correlation. Therefore, in this work, the analysis of the dielectric response at frequencies beyond line-frequency leads to the undeniable benefit of using a multi-frequency dielectric loss procedure to establish higher confidence at the time to state not only technical but also financial decisions.
{"title":"Multi-frequency validation algorithm for measurement and analysis of Dielectric Losses for Power and Distribution Transformers","authors":"D. Robalino, L. Sosa","doi":"10.23919/ARWtr54586.2022.9959952","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959952","url":null,"abstract":"In this work, the authors focus on a highly-practical testing procedure bringing two main benefits to all power industry operators: a) higher confidence on the evaluation of dielectric testing, and; b) better utilization of technical and human resources. In the field, the application of dissipation factor measurements at (typically) 10 kV and at line-frequency (50 or 60 Hz) has been in use for many years without significant changes to the method. Nevertheless, multifrequency measurement of dielectric losses has opened a wider spectrum of analysis for power, distribution transformers and bushings. It is missing though, in the literature, a clear and properly supported discussion about how and when a single frequency measurement is validated with a multifrequency measurement or completely challenged. Important to recognize the link between line-frequency measurement, narrowband measurement (1 – 505 Hz) and full spectrum dielectric response (typically 1 kHz – 1 mHz). Limited information obtained in the frequency domain may identify a faulty unit but may not be used as a preventative test to minimize risk of failure. Preliminary research does address the need for limits of narrowband measurements. This is only possible when a correlation is established between temperature and frequency as it has been done using the well-known Arrhenius correlation. Therefore, in this work, the analysis of the dielectric response at frequencies beyond line-frequency leads to the undeniable benefit of using a multi-frequency dielectric loss procedure to establish higher confidence at the time to state not only technical but also financial decisions.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126004532","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959949
M. Horvat, Z. Jurković, B. Jurišić, T. Zupan, B. Cucic
In the paper high-frequency black-box model of a power transformer winding is presented. The model is based on high-frequency measurements of the winding admittance matrix, using commercial VNA equipment. The winding admittance matrix is measured for every two discs of the winding. The state-space winding model is created using the vector fitting method. The model is verified in the time domain for different voltage impulses and connections.
{"title":"Black-Box Power Transformer Winding Model","authors":"M. Horvat, Z. Jurković, B. Jurišić, T. Zupan, B. Cucic","doi":"10.23919/ARWtr54586.2022.9959949","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959949","url":null,"abstract":"In the paper high-frequency black-box model of a power transformer winding is presented. The model is based on high-frequency measurements of the winding admittance matrix, using commercial VNA equipment. The winding admittance matrix is measured for every two discs of the winding. The state-space winding model is created using the vector fitting method. The model is verified in the time domain for different voltage impulses and connections.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127334737","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959964
Filipe R. Gadotti, S. Cabral, Felipe M. Schuartz
This paper presents the results of a computer simulation analysis combining the application of energy spectral density techniques and evaluation of the rate of rise for checking the voltage withstand of the dielectric system of a current transformer under the incidence of a set of fast transient voltage surges caused by switching operations of an adjacent disconnector. This sort of occurrence has become a critical issue in the electrical power system, being a possible cause of the high number of failures of operating current transformers 550 kV class. The adopted approach is rather new and differs from any of those applied to the analyses of the incidence of VFTO – Very Fast Transient Overvoltage by representing a contribution to the discussions for updating current transformer testing standards.
{"title":"Fast Transient Overvoltage Analysis in Current Transformers due to Disconnector Switching Operation","authors":"Filipe R. Gadotti, S. Cabral, Felipe M. Schuartz","doi":"10.23919/ARWtr54586.2022.9959964","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959964","url":null,"abstract":"This paper presents the results of a computer simulation analysis combining the application of energy spectral density techniques and evaluation of the rate of rise for checking the voltage withstand of the dielectric system of a current transformer under the incidence of a set of fast transient voltage surges caused by switching operations of an adjacent disconnector. This sort of occurrence has become a critical issue in the electrical power system, being a possible cause of the high number of failures of operating current transformers 550 kV class. The adopted approach is rather new and differs from any of those applied to the analyses of the incidence of VFTO – Very Fast Transient Overvoltage by representing a contribution to the discussions for updating current transformer testing standards.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114595755","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959911
Irala Kumar, A. Bakshi
The transformer inner winding conductors may fail due to buckling when an enormous compressive electromagnetic force is applied on them under the short-circuit situation. In literature, the analytical expression for the critical forced buckling stress of the transformer winding is given in which the winding section, between the three adjacent axial supporting spacers, has been modeled as a circular arch. In the model, the axial spacers are considered as a rigid body, but they may have some flexibility. In this paper, an investigation has been done, through case studies, to analyze the influence of the flexibility of the spacers on the critical stress of the inner winding.
{"title":"Effect of Flexibility of Axial Supporting Spacers on the Buckling Strength of Transformer Inner Winding","authors":"Irala Kumar, A. Bakshi","doi":"10.23919/ARWtr54586.2022.9959911","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959911","url":null,"abstract":"The transformer inner winding conductors may fail due to buckling when an enormous compressive electromagnetic force is applied on them under the short-circuit situation. In literature, the analytical expression for the critical forced buckling stress of the transformer winding is given in which the winding section, between the three adjacent axial supporting spacers, has been modeled as a circular arch. In the model, the axial spacers are considered as a rigid body, but they may have some flexibility. In this paper, an investigation has been done, through case studies, to analyze the influence of the flexibility of the spacers on the critical stress of the inner winding.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"4612 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133398148","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959953
P. Quintanilla, R. Altay, A. Santisteban, A. Ortiz, K. Koseoglu
Due to the need to improve the design of power transformers so that they maintain or increase safety while reduce their environmental impact, failures and costs, a design that allows to analyze their cooling systems is developed. A test platform to emulate the behavior of dielectric fluids in a 100 MVA transformer is analyzed in different ways in order to find out whether a whole or individual study of the different parts of the design is better. This process is done with CFD, which also allows to observe differences between different cooling fluids.It is determined a better behavior of mineral oil in all cases simulated. In addition, the feasibility of the analysis by individual parts for closed systems is higher due to the lower time and computational requirements for no high accuracy needs. However, the whole model offers accurately the velocity dependent parameters for ONAN operation.
{"title":"CFD analyses of a test platform with different fluids for use in transformers","authors":"P. Quintanilla, R. Altay, A. Santisteban, A. Ortiz, K. Koseoglu","doi":"10.23919/ARWtr54586.2022.9959953","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959953","url":null,"abstract":"Due to the need to improve the design of power transformers so that they maintain or increase safety while reduce their environmental impact, failures and costs, a design that allows to analyze their cooling systems is developed. A test platform to emulate the behavior of dielectric fluids in a 100 MVA transformer is analyzed in different ways in order to find out whether a whole or individual study of the different parts of the design is better. This process is done with CFD, which also allows to observe differences between different cooling fluids.It is determined a better behavior of mineral oil in all cases simulated. In addition, the feasibility of the analysis by individual parts for closed systems is higher due to the lower time and computational requirements for no high accuracy needs. However, the whole model offers accurately the velocity dependent parameters for ONAN operation.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121542651","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959940
M. Ciesielski, P. Witczak
The paper presents the comparison of 2D and 3D finite elements models of 500 MVA Phase Shifting Transformer showing when they are almost equivalent to each other and also when the simplifications introduced by the 2D approach are too big. Results of numerical calculations obtained at steady and transient conditions which have not been available so far, are illustrated by chosen electromagnetic field distributions. The basic voltage versus current relationships are verified by the factory acceptance test results.
{"title":"The Equivalence Conditions of 2D and 3D Models of Phase Shifting Transformer","authors":"M. Ciesielski, P. Witczak","doi":"10.23919/ARWtr54586.2022.9959940","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959940","url":null,"abstract":"The paper presents the comparison of 2D and 3D finite elements models of 500 MVA Phase Shifting Transformer showing when they are almost equivalent to each other and also when the simplifications introduced by the 2D approach are too big. Results of numerical calculations obtained at steady and transient conditions which have not been available so far, are illustrated by chosen electromagnetic field distributions. The basic voltage versus current relationships are verified by the factory acceptance test results.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"347 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123407181","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959934
L. Rouco, J. Archilla, C. Gavilán
United States Nuclear Regulatory Commission (US NRC) has requested to the US nuclear power generating industry that Open Phase Conditions (OPCs) should be automatically detected. This requirement has been extended by other regulatory bodies worldwide. Several systems for detecting OPCs are available in the marketplace. Remote open phase faults in the supply system of start-up transformers of nuclear power generating stations (NPGSs) pose a major challenge for available detection systems. A remote fault consists of an open phase fault in an intermediate point of the transmission line that feeds the startup transformer of the NPGS. This paper investigates the ability of existing methods to detect a remote open phase fault in the transmission line that feeds the start-up transformer of an NPGS. It also proposes an alternative protection system.
{"title":"Remote Open Phase Faults in the Supply System of Start-up Transformers of Nuclear Power Generating Stations","authors":"L. Rouco, J. Archilla, C. Gavilán","doi":"10.23919/ARWtr54586.2022.9959934","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959934","url":null,"abstract":"United States Nuclear Regulatory Commission (US NRC) has requested to the US nuclear power generating industry that Open Phase Conditions (OPCs) should be automatically detected. This requirement has been extended by other regulatory bodies worldwide. Several systems for detecting OPCs are available in the marketplace. Remote open phase faults in the supply system of start-up transformers of nuclear power generating stations (NPGSs) pose a major challenge for available detection systems. A remote fault consists of an open phase fault in an intermediate point of the transmission line that feeds the startup transformer of the NPGS. This paper investigates the ability of existing methods to detect a remote open phase fault in the transmission line that feeds the start-up transformer of an NPGS. It also proposes an alternative protection system.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128022750","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 : 2022-10-23DOI: 10.23919/ARWtr54586.2022.9959946
Gopalan Ramesh, Ashutosh Sharma, Hemang K. Thakkar
This paper discusses the impact of the use of dry lubricating compound during the manufacturing of a power transformer on the dielectric properties of the solid and liquid insulation. Change in dielectric properties noticed in specific cases are discussed. An experimental set up was used for the research work. The experimental set up and basis for simulating the operating conditions and the impact of the use of dry lubricating compound on the solid and liquid insulation of the transformer are discussed. The test results of the experiment indicate that the dielectric properties namely surface conductivity and DC resistivity of the solid insulation can be affected. This can be measured using the capacitance and power factor test. Manufacturers often study the compatibility of the compound with liquid insulation (mineral oil) only and seldom on the solid insulation. The results suggest that the manufacturers should study the impact of the compounds on the solid insulation as well and not only on liquid insulation.
{"title":"The Impact of the Use of Dry Lubricating Compound on the Dielectric Properties of Solid and Liquid Insulation of a Power Transformer","authors":"Gopalan Ramesh, Ashutosh Sharma, Hemang K. Thakkar","doi":"10.23919/ARWtr54586.2022.9959946","DOIUrl":"https://doi.org/10.23919/ARWtr54586.2022.9959946","url":null,"abstract":"This paper discusses the impact of the use of dry lubricating compound during the manufacturing of a power transformer on the dielectric properties of the solid and liquid insulation. Change in dielectric properties noticed in specific cases are discussed. An experimental set up was used for the research work. The experimental set up and basis for simulating the operating conditions and the impact of the use of dry lubricating compound on the solid and liquid insulation of the transformer are discussed. The test results of the experiment indicate that the dielectric properties namely surface conductivity and DC resistivity of the solid insulation can be affected. This can be measured using the capacitance and power factor test. Manufacturers often study the compatibility of the compound with liquid insulation (mineral oil) only and seldom on the solid insulation. The results suggest that the manufacturers should study the impact of the compounds on the solid insulation as well and not only on liquid insulation.","PeriodicalId":261952,"journal":{"name":"2022 7th International Advanced Research Workshop on Transformers (ARWtr)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133448847","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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