Pub Date : 1994-05-01DOI: 10.1109/ICPS.1994.303554
K. Abdul-Rahman, M. Saied
This paper begins with a brief review of the available literature dealing with the exact modelling of iron-cored coils and transformers. Taking into account the simulation accuracy as well as the required computational burden, the model proposed by Ewart (1986) was chosen to study two important issues related to nonlinear cores: the overvoltages resulting from nonvertical chopping of core or transformer magnetizing currents; and the strongly distorted current, voltage and flux waveforms appearing in systems including linear as well as nonlinear inductances.<>
{"title":"On the exact computation of some typical and dynamic phenomena in power networks including iron-core transformers","authors":"K. Abdul-Rahman, M. Saied","doi":"10.1109/ICPS.1994.303554","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303554","url":null,"abstract":"This paper begins with a brief review of the available literature dealing with the exact modelling of iron-cored coils and transformers. Taking into account the simulation accuracy as well as the required computational burden, the model proposed by Ewart (1986) was chosen to study two important issues related to nonlinear cores: the overvoltages resulting from nonvertical chopping of core or transformer magnetizing currents; and the strongly distorted current, voltage and flux waveforms appearing in systems including linear as well as nonlinear inductances.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125805596","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303588
D. Kunda, E. Neudorf, N. Perris, L.M. Szeto, D.V. Krause
This paper describes electrical impact of nonutility generators (NUG) under 5 MW rating when connected to a distribution feeder. A number of problems are examined including line-to-ground fault level, overvoltage conditions, effect of harmonics, single-phase resonance and transformer backfeed with one phase open. These problems are examined with four different transformer connections. Protection requirements for various supply conditions are discussed. Two actual events involving transformer failure and starting problems are described under operating experiences.<>
{"title":"Electrical impact of a NUG under 5 MW rating when connected to a distribution feeder with various transformer connections","authors":"D. Kunda, E. Neudorf, N. Perris, L.M. Szeto, D.V. Krause","doi":"10.1109/ICPS.1994.303588","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303588","url":null,"abstract":"This paper describes electrical impact of nonutility generators (NUG) under 5 MW rating when connected to a distribution feeder. A number of problems are examined including line-to-ground fault level, overvoltage conditions, effect of harmonics, single-phase resonance and transformer backfeed with one phase open. These problems are examined with four different transformer connections. Protection requirements for various supply conditions are discussed. Two actual events involving transformer failure and starting problems are described under operating experiences.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121805077","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303583
E. Schweitzer, S. Zocholl
This paper discusses the coordination of the characteristics and the backup and redundancy possible with microprocessor relays. The paper reviews the application of negative sequence overcurrent characteristics for unbalanced protection in motors and also covers the rules for coordination of negative sequence characteristics to provide sensitive phase to phase protection in feeders. The paper also covers reset characteristics and the requirements for stator and rotor thermal protection of induction motors.<>
{"title":"Aspects of overcurrent protection for feeders and motors","authors":"E. Schweitzer, S. Zocholl","doi":"10.1109/ICPS.1994.303583","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303583","url":null,"abstract":"This paper discusses the coordination of the characteristics and the backup and redundancy possible with microprocessor relays. The paper reviews the application of negative sequence overcurrent characteristics for unbalanced protection in motors and also covers the rules for coordination of negative sequence characteristics to provide sensitive phase to phase protection in feeders. The paper also covers reset characteristics and the requirements for stator and rotor thermal protection of induction motors.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128890364","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303580
R. Kingston, Y. Baghzouz
Industrial power systems are often characterized as large consumers of reactive power and significant generators of harmonics because most of the load is generally composed of induction motors and static power converters. Consequently, this article analyzes a typical power system configuration where is it desirable to install power factor capacitors and tuned harmonic filters for reactive power compensation and harmonic control. The resonant conditions for a given power factor correction or a harmonic frequency are determined directly from the roots of a quadratic expression. This formulation also allows a quick evaluation of power factor range with excessive harmonic levels, as well as effects of tuned reactors on the resonant frequencies.<>
{"title":"Power factor and harmonic compensation in industrial power systems with nonlinear loads","authors":"R. Kingston, Y. Baghzouz","doi":"10.1109/ICPS.1994.303580","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303580","url":null,"abstract":"Industrial power systems are often characterized as large consumers of reactive power and significant generators of harmonics because most of the load is generally composed of induction motors and static power converters. Consequently, this article analyzes a typical power system configuration where is it desirable to install power factor capacitors and tuned harmonic filters for reactive power compensation and harmonic control. The resonant conditions for a given power factor correction or a harmonic frequency are determined directly from the roots of a quadratic expression. This formulation also allows a quick evaluation of power factor range with excessive harmonic levels, as well as effects of tuned reactors on the resonant frequencies.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131035393","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303569
R. S. Howard, D. Zipse
The paper presents a study on surge arrestor grounding electrodes comparing different grounding electrodes and various backfill materials. This report presents the procedures and results for the first three months of the eighteen month study.<>
{"title":"Grounding/earthing electrode studies. 2","authors":"R. S. Howard, D. Zipse","doi":"10.1109/ICPS.1994.303569","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303569","url":null,"abstract":"The paper presents a study on surge arrestor grounding electrodes comparing different grounding electrodes and various backfill materials. This report presents the procedures and results for the first three months of the eighteen month study.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124130026","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303573
L. Yu
The lattice diagram has been widely recognized and adopted to analyze the voltage surges produced at a particular location in an electrical system. These transient surges are caused by traveling waves induced by lightning strikes or switching operations. The lattice diagram can be used effectively, but the required computations are tedious. A simplified approach for computing induced voltage surges based on mathematical derivation is presented. This method permits a quick evaluation of both an initial and crest surge magnitude and wave shape based on a given incoming surge and the surge impedances of the electrical elements involved. Sample calculations from the lattice diagram and the proposed quick evaluation are compared.<>
{"title":"Quick evaluation of voltage surge in electrical power systems","authors":"L. Yu","doi":"10.1109/ICPS.1994.303573","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303573","url":null,"abstract":"The lattice diagram has been widely recognized and adopted to analyze the voltage surges produced at a particular location in an electrical system. These transient surges are caused by traveling waves induced by lightning strikes or switching operations. The lattice diagram can be used effectively, but the required computations are tedious. A simplified approach for computing induced voltage surges based on mathematical derivation is presented. This method permits a quick evaluation of both an initial and crest surge magnitude and wave shape based on a given incoming surge and the surge impedances of the electrical elements involved. Sample calculations from the lattice diagram and the proposed quick evaluation are compared.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125441982","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303555
G.J. Ratasky, J. Shubik
This paper identifies key issues of plant-wide electrical reliability evaluations and design for water and wastewater treatment facilities. The presentation of key issues is based on extensive experience represented in case studies involving system configurations, power quality, standby/emergency power, electric utility service arrangements, and other pertinent issues. In addition, these case studies address EPA and California Title 22 requirements, all with regard to reliable design of electrical systems.<>
{"title":"Electrical power system reliability case studies for water and wastewater treatment facilities","authors":"G.J. Ratasky, J. Shubik","doi":"10.1109/ICPS.1994.303555","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303555","url":null,"abstract":"This paper identifies key issues of plant-wide electrical reliability evaluations and design for water and wastewater treatment facilities. The presentation of key issues is based on extensive experience represented in case studies involving system configurations, power quality, standby/emergency power, electric utility service arrangements, and other pertinent issues. In addition, these case studies address EPA and California Title 22 requirements, all with regard to reliable design of electrical systems.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"504 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116553060","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303567
F. Dawalibi, W. Xiong, Jinxi Ma
When lightning strikes an electric substation, large currents generated by the stroke flow in the aboveground structures and grounding system and dissipate in the soil. The electromagnetic fields generated by such high currents may cause damage to equipment and may be dangerous to personnel working nearby. In this paper, the frequency and time domain performance of a substation subjected to a lightning strike is described and discussed. The computed scalar potentials, electric fields and magnetic fields are presented graphically as a function of spatial coordinates, as a function of time and as a function of both. Two cases are considered. The first case examines the substation grounding system only, while the second case includes an aboveground structure as well. It is believed that the results of the second case have not been published before. A double exponential lightning surge current is injected at one corner of the substation. The response of the grounding system to the frequency domain electromagnetic spectrum of this signal is computed by a frequency domain electromagnetic field analysis software package. The temporal and spatial distributions of the electromagnetic fields inside and near the substation are obtained by an inverse Fourier transformation of all these responses. The presence of a soil with an arbitrary resistivity and permittivity is accurately taken account. Analysis sheds some new light on understanding of the effects which take place at the higher frequencies.<>
{"title":"Transient performance of substation structures and associated grounding systems","authors":"F. Dawalibi, W. Xiong, Jinxi Ma","doi":"10.1109/ICPS.1994.303567","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303567","url":null,"abstract":"When lightning strikes an electric substation, large currents generated by the stroke flow in the aboveground structures and grounding system and dissipate in the soil. The electromagnetic fields generated by such high currents may cause damage to equipment and may be dangerous to personnel working nearby. In this paper, the frequency and time domain performance of a substation subjected to a lightning strike is described and discussed. The computed scalar potentials, electric fields and magnetic fields are presented graphically as a function of spatial coordinates, as a function of time and as a function of both. Two cases are considered. The first case examines the substation grounding system only, while the second case includes an aboveground structure as well. It is believed that the results of the second case have not been published before. A double exponential lightning surge current is injected at one corner of the substation. The response of the grounding system to the frequency domain electromagnetic spectrum of this signal is computed by a frequency domain electromagnetic field analysis software package. The temporal and spatial distributions of the electromagnetic fields inside and near the substation are obtained by an inverse Fourier transformation of all these responses. The presence of a soil with an arbitrary resistivity and permittivity is accurately taken account. Analysis sheds some new light on understanding of the effects which take place at the higher frequencies.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128805541","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303547
G. Parise
For near to generator short-circuit analysis, it is well known that a rigorous calculation procedure requires the use of complex dynamic models of power system components. In most practical cases, however, it is sufficient to adopt simplified and standard based calculation methods. For these cases the paper suggests a new approach of the short-circuit models of power system components based on the "characteristic" currents method. The paper, at first, presents a short overview of the IEC Standard 909, assumed as reference for the proposed approach. The calculation assumptions and the simplifications of the IEC Standard are pointed out in order to evidence how the new approach proposed obtains conservative, but more accurate results. The "characteristic" currents procedure is successively applied to a sample network with external feeder and internal generation and with motor load. The same network is analyzed by means of the IEC procedure and by means of a computer program able to consider dynamic models of electrical equipment. A comparison among these approaches is carried out in order to validate the "characteristic" currents method.<>
{"title":"Near-to-generator short-circuit analysis in industrial and commercial power systems: the \"characteristic\" currents method","authors":"G. Parise","doi":"10.1109/ICPS.1994.303547","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303547","url":null,"abstract":"For near to generator short-circuit analysis, it is well known that a rigorous calculation procedure requires the use of complex dynamic models of power system components. In most practical cases, however, it is sufficient to adopt simplified and standard based calculation methods. For these cases the paper suggests a new approach of the short-circuit models of power system components based on the \"characteristic\" currents method. The paper, at first, presents a short overview of the IEC Standard 909, assumed as reference for the proposed approach. The calculation assumptions and the simplifications of the IEC Standard are pointed out in order to evidence how the new approach proposed obtains conservative, but more accurate results. The \"characteristic\" currents procedure is successively applied to a sample network with external feeder and internal generation and with motor load. The same network is analyzed by means of the IEC procedure and by means of a computer program able to consider dynamic models of electrical equipment. A comparison among these approaches is carried out in order to validate the \"characteristic\" currents method.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"233 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133307509","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 : 1994-05-01DOI: 10.1109/ICPS.1994.303572
E. Zhou, A. Naslé
Direct current (DC) power distribution systems have been extensively used in nuclear power plants and transit systems. The major concern of DC system studies is the voltage and voltage drop at load buses. A Newton-Raphson method based DC load flow algorithm and a DC system simulation package have been developed and reported in this paper. DC generators, batteries, AC/DC rectifier converters and constant power, constant current, constant resistance loads can be considered in the simulation. Time-varying and moving loads can also be simulated.<>
{"title":"Simulation of DC power distribution systems","authors":"E. Zhou, A. Naslé","doi":"10.1109/ICPS.1994.303572","DOIUrl":"https://doi.org/10.1109/ICPS.1994.303572","url":null,"abstract":"Direct current (DC) power distribution systems have been extensively used in nuclear power plants and transit systems. The major concern of DC system studies is the voltage and voltage drop at load buses. A Newton-Raphson method based DC load flow algorithm and a DC system simulation package have been developed and reported in this paper. DC generators, batteries, AC/DC rectifier converters and constant power, constant current, constant resistance loads can be considered in the simulation. Time-varying and moving loads can also be simulated.<<ETX>>","PeriodicalId":197013,"journal":{"name":"Proceedings of Industrial and Commercial Power Systems Conference","volume":"10 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131776571","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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