Proceedings. Joint International Power Conference Athens Power Tech,最新文献

{"title":"On the Adequacy of the Modal Approach in Modeling of Three Phase Untransposed Transmission Lines","authors":"A. Soysal, A. Semlyen","doi":"10.1109/APT.1993.686838","DOIUrl":"https://doi.org/10.1109/APT.1993.686838","url":null,"abstract":"Modal transformations at a fixed frequency are normally used in the calculation of transmission line transients for tlie diagonalization of the propagation aid characteristic admittance transfer matrices over a wide frequency range. The adequacy of these transformatioils is discussed for different tluee pliase, double circuit line arrangements. A criterion teimed Non-Diagonality Index (NDI) is introduced for the evaluation of tlie error due to the approxunate diagonalization. ?lie base cases are compaxed in terms of NDI and general considerations iue presented for the selection of the optimal transfoilnation frequency to iinpiove the accuracy of the modal analysis. INTRODUCTION The modeling of trammission lines his been the object of much effort hi the development of progranis, such as the E M \" , for tlie study of electromagnetic transients. In fact, transmission lines are the most fundameiital components of a power system and tlie success of the time domain solutions depends significantly on the accuracy of the line model being used. Due to the frequency dependence of tb: parameters resulting from the coniplex field phenomena in the ground and inside the conductors, tlie modeling of transmission lines is always based on frequency domain forniulatioii, while transient analyses and netwoik simulations are naturally perfomied in the time domain 111. In conventional Eh4TP studies modal transformations are used for modeling of niultipliase lines. The calculations related to traveling waves are performed for the decoupled modes aid pliase domain variables are obtained by inverse transfoimation. Various leal trruisfonnations a e available to achieve an efficient decoupling between the phases of balanced lines [2J. In tlie general case of untransposed inultipliase lines with non-symmetrical wire arrangements, eigenaialysis may be perfoiled to obtah the appropriate modal transformation matrices. However, due to the fiequency dependence of the parameters, a constant transformation matrix can no! provide a perfect diagonalization over a wide frequency range [3]. 111 [4] and [5 ] it has been shown that a particular selection of the transformation frequency can hnprove the accuracy of the time domain solutions. The modal approach is principally based on the assumption that the non diagonal elements of the transformed matrix are negligible over the considered frequency range. For unbalanced lines this assumption is acceptable if the frequency dependence is sufficiently small, so that the non-diagonality does not produce significant errors. In this paper the effectiveness of modal transformations is discussed in terms of the modeling errors. A criterion is introduced Paper APT 377-18-25 accepted for presentation at the lEEE/N'rUA Athens Power Tech Conference: \"Planning, Operation and Control of Today's Electric Power Systems\", Athens, Greece, Sept. 54,1993. Adam Semlyen Depaiment of Electrical Eugineering University of Toronto Toronto, Ontario, Canada, M5S 1A","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114223630","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}

{"title":"Training Simulators For Power System Operation In Power Utilities Of Japan","authors":"Y. Sekine, K. Takahashi, I. Kurihara","doi":"10.1109/APT.1993.673882","DOIUrl":"https://doi.org/10.1109/APT.1993.673882","url":null,"abstract":"Present si tuation of dispatcher training simulators for power system operation i n Japan is surveyed. Simulatoraided education/training programs now widely implemented i n power companies a re a l so referred. Specifically, t h i s paper presents Japan's recent s t a t u s of power sysLem opera t ion , objective of a training simulator, simulation models of power system dements , man-machine in t e r f ace , layout of t ra in ing simulator f a c i l i t i e s , t ra in ing/educa t ion programs, fu tu re challenges i n power companies, and s o forth.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126255776","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}

{"title":"Introduction of Microprocessor Technology for System Protection Basic Considerations","authors":"R. Poncelet, J. Maun","doi":"10.1109/APT.1993.686891","DOIUrl":"https://doi.org/10.1109/APT.1993.686891","url":null,"abstract":"To respect space limitation, this communication does neither present power system theory, nor protective releying principles, nor digital systems which are supposed to be known, but restricts itself to the influence of the developments in microprocessors (hardware and software), in digital signal processing, elgorithmic, numerical analysis and in digital communications on present end future digital relaying practice. It is besed on our long-term experience illustrated for example by our cooperation with A. Phedke in the early eighties to implement the S.C.D.R. algorithm and since 1985 by our close association with Siemens in research and development for many members of their family of digital relays.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132370395","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}

{"title":"Evaluation Of Induced Eddy Currents In Transformer Sheets Due To Edge-burrs, Employing Computer Aided Design Programs","authors":"M.B. Aimoniotis, A. Moses","doi":"10.1109/APT.1993.673914","DOIUrl":"https://doi.org/10.1109/APT.1993.673914","url":null,"abstract":"Edge-burrs (rough edge cuttings) are produced during the slitting and cutting of transformer core sheets to the required dimensions. Edge-burrs can break the insulation between adjacent transformer laminations, allowing high currents to circulate from one core sheet to another, with resulting increases in the eddy current loss. In order to predict the influence of burrs on the power losses of transformer cores, the paths and values of eddy currents, simulated in computer core models, were computed. Each computer modcl represented different burr positions and sizes in the core, electrically \"shorting\" successive laminations together.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133934869","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}

{"title":"Power Transformers Overloading","authors":"A. Kartas, D. Tsanakas, A. Sferides","doi":"10.1109/APT.1993.686857","DOIUrl":"https://doi.org/10.1109/APT.1993.686857","url":null,"abstract":"A&!mct 'I'hc ratcd power of powcr trruisloniicrs is determined bescd upon n continuous load and constant tcinpcriiturc of tlic cooling IiiCdinln. l'hcsc features inllucnl thc life cxpcctaricy of powcr transformcr. Ilowcvcr, in practicc, constant load mid constant teniperaturc of tlie cooling nir CNI not bc acliicved. Significant variations apl,car during citlicr tlic daily or thc sctisond operatioil. I n many cmcs the overloading (loading above tlic nameplate rating) is possible without a reduction 06 life cxpcctancy, taking into account tlic actual daily load profiles (the duration of pcak loads is rtsually a sinali p u t of Ihe daily cyclc, especially pcak loads which arc caused by clcctric heat storagc) and the rcspcctive variable tcnipcratwc of tlic cooling air. I n this paper thc division of Grcccc in ambient temperature zoncs of thc wciglitcd ina?tiniuni and niinimum ambient tcrnpcraturc 11s been inadc. Wilh this division i t can bc tnkcn into account tlic daily vari:tioii of Nnbicol tcniperaturc concci-ning tlic dctcrinination of thc power transformers tlicniial agcing. 'l'hc power transformers ageing WELT calculated according 10 1I:C Stmdard 354/199 I \"1.oading guide lor oil-iniincrscd powcr transfonners\". Tlic agcing was calculatcd taking Into account tlie actunl daily load profile and tlie respcctive daily anibicnt tcrnpcratirrc profilc, using tlic prograin that has bcen dcvclopcd. 'l'lic daily load prolilc is approxiniated with 21 constatit load intervals of I hour duration and tlie daily runbienl tcnipcratiirc profilc 'as a sinusoidal vuiation bctween tlic niariinuin iind the niininiuni dnily olnbicnt tcrnpcraturc. An overloading cstiinotion of powcr transfonners up to 1M) MVA has bccn made. taking into account tlic typical dally load profiles and the ainbicnt tcnipemturc i n Greece. It was resulted the ionding above tlic nuncpiatc rating from 21% t o 29% in winter a i d froin 8% to 11% in siinuncr.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131571819","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}

{"title":"Design Considerations of a Voltage Source Inverter Fed Squirrel Cage inducted Motor for Electrical Vehicle","authors":"A. Kladas, S. Manias, J. Tegopoulos","doi":"10.1109/APT.1993.673909","DOIUrl":"https://doi.org/10.1109/APT.1993.673909","url":null,"abstract":"AbstracL 'The paper descr ibes the main f e a t u r e s aL the des ign s t age or an induction motor supplied by a I'WM control led va r i ab le fi-cquency inve r t e r f o r an e l e c t r i c a l vciiicla d r ive . Standard pi, incipleo f o r pr-ci in;innry design are reviewed and the motor pa:.nntcters ev:xlua.tion by means of the f i n i t e element mccliod is implemeni.ed. Emphasis I s given on ~decisioxis favored by this app l i ca t ion : low r o i o r r e s i s t a n c e , higher leakage induc?a.nce, smal I numbel. O F poles , increased cool ing requirements. F ina l ly , the importance of the PWt4 waveform on lfic performance of the system is irivesiigated by means oi' coupled f i e l d ' s and ( c i r c u i t ' s approach.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126591888","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}

{"title":"Open Ems in Practice","authors":"Y. Tadec, J. Coullon, C. White, N. Peterson","doi":"10.1109/APT.1993.686855","DOIUrl":"https://doi.org/10.1109/APT.1993.686855","url":null,"abstract":"","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133348031","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}

{"title":"Optimal Power Flow Application to Composite Power System Reliability Analysis","authors":"A.P. Sakis, F. Xia","doi":"10.1109/APT.1993.686867","DOIUrl":"https://doi.org/10.1109/APT.1993.686867","url":null,"abstract":"This paper presents a method which applies an efficient optimal power flow model to composite power system reliability analysis. It is based on the contingency enumerative approach. The optimal power flow is the premier tool for contingency effects analysis. The method used here incorporates the process of economic dispatch, observes the operating constraints and determines tlie amount of load curtailment after exhaustion of all other options. The optimization problem is solved either with the simplex method or with an interior point algorithm. Tlie perforniiance evaluation of the optimal powcr flow model for a large power system is provided. Finally, the reliability computations are illustrated w i h a simple example.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131268080","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}

{"title":"Fast and Efficient Power Converter System Simulation Using High Level Languages","authors":"J. Espinoza, G. Joós, P. Ziogas","doi":"10.1109/APT.1993.686851","DOIUrl":"https://doi.org/10.1109/APT.1993.686851","url":null,"abstract":"With the advent of ponerful circuit simulation tools such as Spice-based simulators, the simulation of a power converter system has been reduced to the generation of an adequate electric circuit model of the system. However, this approach often leads tu1 large execulion times and uncertain results associated with i:onvergeiicc problems. Alternatives are tlie switched-circuit simulators, where the switches are idealized by assuming zero on-iresistance, infinitc off-resistance and instantaneous switching. Though these simulators overcome the long execution times arid convergence problems, both Spicebased and switched-circuit simulators have execution times proportional to the nuniber of power switches. Furtherinore, nrodern control techniques are difficult to implement. A practical and efficient solution that allows use of the discrete state approach is available today in the form of powerful and user friendly high level language compilers, such as C and Basic. This paper illustrates the cieair advantages of combining this approach with Basic to simulate poiscr converter systems. Moreover, the use of discrete states, instead of ideal switches, to model static power converters reduces execution time and introduces high flesibilily in iriiplemenli iig coniplex PWM pattern generation algorilhins, such as spacc vector or predictive control techniques, rcgardlcss of the power and control circuit structure aridlor coni plexi ty. I. INrI1OI)UCTION Siniulation of inpul/catput cliaracteristics and transient beliavior is an essential step in thc design of power converter systems. The rccent devclopment of powerful circuit simulation tools such ai; Spice-based siinulators have reduced Paper APT 416-1 1-28 accepted for presentation at the IEEE/MTUA Atliens Power Tcch Conference: “Planning, Operation and Coiitrol of Today’s Electric Power Systeins”, Athens, Greece, Sept. 54,1993. the simulation process to the generation of adequate electric circuit models of the power converter system. However, in these analog siiriulation packages, the presence of nonlinearities, that are inherent in power converter switching operation, results in long execution times, potential convergence problems, and occasionally unreliable results. In particular, the simulation of a switching transition rcquires sinall time steps to ensure sunicient numerical accuracy mid tlie iterative process iiiay lead to convergence problems at these switching points [ 11. Other types of general purpose simulators are the switchedcircuit simulators [2]. These packages are characterized by the use of idealized switch models. In fact, tliese are often modeled by zero (z inili olims) on-resistance, infinite (. I mega ohms) off-resistance and instantaneous switching. Though these packages reduce execution tinies and eliminate convergence problems (there is usually no accuracy check), both Spicebased and switching-circuit siinulators have execution times proportional to the nuniber of power switches (or in","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"162 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127411916","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}

{"title":"Reliability Analysis of Distribution Networks with Local Generation Using Fuzzy Sets","authors":"T. Seitz, H. Haubrich, A. Montebaur","doi":"10.1109/APT.1993.686913","DOIUrl":"https://doi.org/10.1109/APT.1993.686913","url":null,"abstract":"In the area of power distribution systems, relinbiltiy evaluations tend to be very complex and nietliodically regmdcd difficult. Especially. if I O G ~ generating units, being operated according to heat deniand, are considered cxdcul:itioii t h e and the data basis both bcconie serious problems. This paper depicts the application of Fuzzy Set Tlieory (FST) for more suitable problem solving in tllis field. It includcs an introdtiction to the basic idea of the theory. Aathcrniore, its applications in tlie field of electric energy systcnis cngineering are discussed briefly. The new rnetliod is applied to a model systeni tliat was developed in close cooperntioii with an utility. First results and possible effects on the network structure arc discussed.","PeriodicalId":241767,"journal":{"name":"Proceedings. Joint International Power Conference Athens Power Tech,","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115589165","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}