WorldCat Identities

Štumberger, Gorazd

Overview
Works: 255 works in 261 publications in 2 languages and 313 library holdings
Genres: Conference papers and proceedings 
Roles: Thesis advisor, Other, Author, Photographer, Editor
Classifications: TK5105.5, 001.64404
Publication Timeline
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Most widely held works by Gorazd Štumberger
Program by Mednarodno posvetovanje Komunalna energetika( Book )

3 editions published between 2003 and 2014 in Slovenian and held by 10 WorldCat member libraries worldwide

Elementi zaščite in lokalne avtomatike v EES in industrijski energetiki : poročilo o delu za leto 1991 by Bojan Grčar( Book )

2 editions published between 1992 and 1993 in Slovenian and held by 4 WorldCat member libraries worldwide

The objective of our research was to deepen the knowledge necessary for the design and the prototype realization of an integrated digital transformer protection. An original method that allows the consideration of nonlinear magnetic phenomena in power transformer modeling is proposed. Special attention is paid to the analysis of influential quantities that cause harmonic current distortions in steady and transient states. An improved integrated power transformer algorithms structure is presented. The proposed prototype protection realization was objectively evaluated on the basis of numerous testings. A new signal processing procedure for a three-phase system is included. It is based on a procedure which allows the elimination of redundant information, and implicit filtering can be used for the design of various new protection algorithms. Some extensions of the research project on the automation and protection of laboratory power plants are presented
Načrtovanje in analiza eksperimentalnega sistema aktivnih magnetnih ležajev : doktorska disertacija by Boštjan Polajžer( Book )

1 edition published in 2002 in Slovenian and held by 4 WorldCat member libraries worldwide

Magnetno nelinearni dinamični model sinhronskega motorja s trajnimi magneti : doktorska disertacija by Miralem Hadžiselimović( Book )

1 edition published in 2007 in Slovenian and held by 3 WorldCat member libraries worldwide

Delo obravnava dvoosni magnetno nelinearni dinamični model sinhronskega motorja s trajnimi magneti (SMTM), ki je zapisan v orientaciji magnetnega sklepa trajnega magneta. V delu je predstavljena celotna matematična izpeljava modela, ki se začne s splošnim zapisom električnih in mehanskih ravnotežnih enačb trifaznega motorja. V enačbah so magnetno ne linearne lastnosti železnega jedra opisane s karakteristikami magnetnih sklepov navitij posameznih faz. Omenjene karakteristike so odvisne od položaja rotorja in tokov v navitjih vseh treh faz. S trifazno-dvofazno transformacijo in rotacijsko transformacijo je zapis originalnega trifaznega modela preveden v zapis dvoosnega modela, orientiranega z vektorjem magnetnega sklepa trajnega magneta. Tako postanejo magnetno ne linearne karakteristike železnega jedra funkcija položaja rotorja in dveh tokov. Prvi tok leži v smeri vektorja magnetnega sklepa trajnega magneta (os d), drugi pa je pravokoten nanj (os q). V ravnotežnih enačb ah nastopajo tudi magnetni sklepi in njihovi odvodi. Slednje je mogoče izraziti s produkti parcialnih odvodov magnetnih sklepov po ustrezni spremenljivki s časovnimi odvodi teh spremenljivk. Magnetno nelinearni dinamični model SMTM je neuporaben, dokler niso določene magnetno nelinearne karakteristike in njihovi parcialni odvodi. Te karakteristike predstavljajo spremenljive parametre izpeljanega modela in so lahko določene eksperimentalno ali pa z metodo končnih elementov. Karakteristike delimo v dve skupini. V prvo sodijo karakteristike magnetnih sklepov, ki so posledica magnetnega vzbujanja trajnega magneta. V drugo skupino pa spadajo karakteristike magnetnih sklepov, ki so posledica statorskih tokov. Metode za eksperimentalno in numerično določitev opisanih karakteristik so podrobno razložene. Z ustrezno določenimi magnetno nelinearnimi karakteristikami magnetnih sklepov so v magnetno nelinearnem dinamičnem modelu SMTM zajeti vplivi nasičenja magnetnega materiala, križne sklopitve, vpliv statorskih utorov ter vplivi geometrije motorja in lastnosti trajnih magnetov. V delu je opisana tudi izvedba magnetno nelinearnega dinamičnega modela SMTM v programskem paketu Matlab/Simulink, ki omogoča izvajanje simulacijskih izračunov. Rezultati teh izračunov so primerjani z laboratorijskimi meritvami in z rezultati izračunov z metodo končnih elementov
Analiza obratovanja v resonančno ozemljenih srednjenapetostnih omrežjih : doktorska disertacija by Miran Rošer( Book )

1 edition published in 2014 in Slovenian and held by 3 WorldCat member libraries worldwide

The doctoral thesis deals with the analysis of conditions that appear in a resonant earthed medium voltage distribution system in the cases of earth faults. The measurements and experiments performed in a real operating network are used to show the problems caused by specific arc faults that occur when the conductor touches branches or trees, when the conductor falls to the ground during operation and in the cases of medium voltage cable insulation failure. The resonant earthed neutral enables complete compensation of the capacitive component of the earth fault current, whilst it fails to compensate the active component. The active component of the earth fault current results from losses due to inadequate insulation of the network and losses in the Petersen coil. Similarly, also the higher order harmonic components of the earth fault current, caused by nonlinear loads in the distribution network, cannot be compensated with resonant earthing. The thesis shows that in the case of arcing faults even a perfect compensation of the capacitive component in the earth fault current is insufficient to effectively extinguish arc at the fault location. The arc is continuously maintained by the active component in the earth fault current due to the losses and higher order harmonic components. The core of the thesis is the implementation of the fault current path control method in a resonant earthed system, where an earthing switch is employed to earth the medium voltage busbar of the faulted phase. In this way, the arc at the fault location is immediately and effectively extinguished in all cases of earth faults. The most significant contribution of the proposed fault current path control method is to provide a continuous operation in the cases of not self-extinguishing arcing faults, safe location of faults and their elimination, all without supply interruptions. The implementation of the proposed fault current path control method directly affects the power supply quality. In this thesis, the proposed fault current path control method is dealt with analytically using equivalent circuits, phasors and impedances, as well as numerically using dynamic network analysis. The theoretically obtained results are completely confirmed by an extensive filed-testing, performed in the transformer substation Krško under conditions of normal distribution network operation. A special effort has been made to design, develop and manufacture special equipment, indispensable to perform experiments in an operating medium voltage distribution network in the safe manner
Vpliv magnetnih nelinearnosti sinhronskega stroja s trajnimi magneti in izkoristek pogona z brezsenzorskim vodenjem : doktorska disertacija by Željko Plantić( Book )

1 edition published in 2013 in Slovenian and held by 3 WorldCat member libraries worldwide

This Ph.D. thesis deals with the efficiency improvement of an electrical drive. It focuses on the efficiencies of inverter and electrical machine, which, in the given case, is a Permanent Magnet Synchronous Machine (PMSM). The efficiency of an electrical drive depends on the power losses in individual elements of the drive. The findings of performed analysis of driveʼs losses are used to select the most suitable solutions for efficiency improvements in individual drive elements and in the entire drive. Only those solutions that can be applied on the existing inverter and PMSM are considered, which means by the control realization and proper setting of inverter parameters. In the case of PMSM vector control realizations, the generation of the direct- and quadrature-axis reference currents has substantial impact on drive efficiency. In the reference currents generation the Maximum Torque Per Ampere (MTPA) characteristics are used. They provide the maximum torque per unit of current. In order to assure driveʼs maximum efficiency, the Maximum Efficiency (ME) characteristics are introduced in the reference currents generation. Since the analytical descriptions of the MTPA and ME characteristics contain some variable parameters that are difficult to be determined, the MTPA and ME characteristics are determined experimentally and given in the form of look-up tables. The PMSM vector control realization is modified by the inclusion of MTPA and ME characteristics applied for reference currents generation, which leads to the drive efficiency improvementthat is confirmed by measurements. The drive efficiency is further improved by the use of optimal modulation frequency and by the variable DC-busvoltage. The last one can substantially improve the efficiencies of variable speed drives operating at partial load and low speeds. All described solutions for efficiency improvement are applied to improve the efficiency of the PMSM sensorless control realization based on the active flux principle. The result is a mechanically robust and reliable sensorless drive realization,where the reference currents generation based on MTPA and ME characteristics improves the drive efficiency. The findings of this Ph.D. thesis are confirmed by experiments and measurements
Brezsenzorsko vodenje sinhronskega stroja s trajnimi magneti za puhala s širokim razponom hitrosti vrtenja by David Stojan( Book )

1 edition published in 2013 in Slovenian and held by 3 WorldCat member libraries worldwide

Avtomatizacija vodenja male elektrarne : raziskovalna naloga by Drago Dolinar( Book )

3 editions published between 1993 and 1995 in Slovenian and held by 3 WorldCat member libraries worldwide

Raziskovalno poročilo opisuje prvo fazo avtomatizacije vodenja male elektrarne. V prvem poglavju je podan kratek opis elektromehanske opreme agregata. Agregat je sestavljen iz sinhronskega stroja moči 30 KVA, ki v blok stiku s transformatorjem deluje otočno ali pa sinhronizirano z omrežjem. Sinhronski stroj je gnan z enosmernim tujevzbujanim motorjem, ki mu zaradi usteznega načina vodenja lahko karakteristike oblikujemo tako, da se obnaša kot vodna ali parna turbina. V drugem delu poročila je opisan sistem avtomatiziranega vodenja celotnega agregata. Vodenje sistema je zasnovano hierarhično. Na najnižjem nivoju se nahajajo PLC krmilniki in zmogljivi signalni procesorji, ki so s procesnim nivojem povezani z vhodno izhodnimi vmesniki. Krmilnik in signalni procesorji so s pomočjo ustreznega programskega vmesnika povezani s centralnim nadzornim računalnikom na nadzornem nivoju, ki dopušča dodatno povezovanje v računalniško mrežo. Celoten sistem vodenja je realiziran v okviru profesionalnega programskega paketa modularno zato, da omogoča preprosto prenosljivost posameznih funkcij na podobne primere vodenja industrijske energetike. V prvem delu poročila je detajlno opisan krmilni segment nadzornega nivoja. Regulacijske naloge in koordinacija zaščitnih sistemov bo predmet raziskovalnega dela v prihodnjem letu
Elektromagnetne naprave - temeljne računske metode : zaključno poročilo o rezultatih opravljenega znanstveno-raziskovalnega dela na področju temeljnega raziskovanja 1993-95 : številka pogodbe J2-5148-796-95 by Božidar Hribernik( Book )

1 edition published in 1996 in Slovenian and held by 3 WorldCat member libraries worldwide

During the past three years we have developed a programme solution for the three most widely-used methods (FEM-finite element method, BEM-boundary element method and HM hybrid method) for CAD of electro-magnetic devices. Because o the differences and specificness in the design of these devices we used three scalar potential variants for the calculation of electromagnetic field. In research of numerical methods for force and torque calculations basic methods: Maxwell stress method, Virtual work method and Magnetising current method. All of them are based on numerical solutions of magnetic conditions. To increase the accuracy of the calculation and to achieve better adjustability to the methods for the field calculation and insensitivity to the user - defined parameters several modifications were carried out on the basic methods. The developed methods were verified by measurements on real models. For the purpose of the analysis and synthesis of the electrical machines the some new dynamic models of the AC electrical machines were developed. The special attention was paid to determination of the parameters of the mentioned models. The new methods for the high performances control of the AC machines has been also developed
Ovrednotenje vpliva nesimetričnih obremenitev in višjih harmonskih komponent na izgube v transformatorju : doktorska disertacija by Matej Toman( Book )

1 edition published in 2008 in Slovenian and held by 3 WorldCat member libraries worldwide

This work deals with the evaluation of the influence of asymmetrical loads andhigher order harmonics on transformer losses. In order to perform such evaluation, the primary and secondary currents, voltages and powers were calculated. The analysis of transformer losses is based on orthogonal current decomposition. The primary and secondary currents are decomposed in the time and frequency domains. The analysis of transformer losses and RMS values of the orthogonal currents components show, that transformer losses are increasedwhen orthogonal currents that do not contribute to the energy transmission are present. In order to come to this finding, the generalized power factor, scattered factor, reactive factor and unbalanced factor were introduced. The introduction of these factors is based on orthogonal current decomposition. When we perform simulations and analysis on the primary and secondary side of the transformer in the case of asymmetrical loads and higherorder harmonics, the exact current and voltage waveforms are needed. Therefore a transformer model which gives us realistic representation of the real transformer must be used. At first we used finite element (FE) model. When the FE transformer model was supplied with the currents measured on a load, the differences between the measured and calculated voltages and currents were substantial. The reason is in the description of the magnetically nonlinear iron core characteristic. The transformer's iron core is in commercial programs normally accounted for by the magnetizing curve. In this way the hysteresis phenomenon of the iron core is neglected. Besides that, the magnetizing curve must be monotony decreasing in order to assure the convergence of the calculation. All these limits cause reduction of the accuracy of the FE transformer model. Therefore, we were forced to develop our own three-phase dynamic transformer model. This transformer model uses lumped parameters. The magnetically nonlinear behavior of the transformer's iron core is accounted for by the inverse Jiles-Atherton (J-A) hysteresis model. The inverse Jiles-Atherton (J-A) hysteresis model was developed form the original (J-A) hysteresis model by adding parameter k as a function of the magnetic field intensity. This approach is presented in this work for the first time and can not be found in accessible literature. The parameters of the hysteresis models are determined by the optimization algorithm called differential evolution. All equations of the original and inverse (J-A) hysteresis model are written in differential form, so that they can be easily included in simulation programs
Načrtovanje in analiza sinhronskega stroja s trajnimi magneti in dvojnim rotorjem : doktorska disertacija by Peter Pišek( Book )

1 edition published in 2013 in Slovenian and held by 3 WorldCat member libraries worldwide

Doktorska disertacija obravnava postopek načrtovanja, analizo in izdelavo prototipa posebnega sinhronskega stroja s trajnimi magneti in dvojnim rotorjem (SSTMDR) ter utemeljitev vzročno-posledičnih povezav med magnetno sklopljenimi aktivnimi deli SSTMDR, namenjenega za uporabo v naprednih hibridnih pogonih vozil. Predviden postopek načrtovanja sloni na 2D in 3D izračunih modela SSTMDR s pomočjo metode končnih elementov (MKE), kjer je upoštevan vpliv geometrije stroja, vpliv magnetnih nelinearnosti stroja in materiala trajnih magnetov v ustaljenih obratovalnih stanjih. Poseben poudarekv fazi načrtovanja stroja je namenjen razvoju nove konstrukcije zunanjega rotorja SSTMDR, ki sloni na izvedbi zunanjega rotorja s potopljenimi trajnimi magneti (TM) in enim TM na pol ter izgradnji dodatnih magnetnih pregrad, ki pomembno vplivajo na karakteristike stroja. Predlagana izvedba z uporabo potopljenih TM in uporabi enega TM na pol tako bistveno zmanjšuje celoten volumen TM v SSTMDR, prav tako pa odpravlja težave povezane s centrifugalno silo, ki lahko nastopijo pri višjih vrtljajih z uporabo površinskih TM. V nadaljevanju je kot ena izmed ključnih faz konstruiranja SSTMDR predstavljena analiza vpliva števila statorskih utorov/polov zunanjega rotorja/utorov notranjega rotorja na karakteristike stroja. Na podlagi podanih kriterijev predstavlja najugodnejša kombinacija v opravljeni analizi osnovo za izgradnjo prototipa SSTMDR. Izdelan prototip SSTMDR tako omogoča verifikacijo ustreznosti predlaganega postopka načrtovanja stroja in verifikacijo principa delovanja SSTMDR. Eksperimentalno določanje elektromehanskih karakteristik stroja je izvedeno za primer generatorskih testov SSTMDR s pasivnim bremenom brez uporabe vodenja, kakor tudi za primer motorskega in kombiniranega motorskogeneratorskega režima delovanja, kjer je za delovanje potrebno ustrezno vodenje stroja. Ujemanje izračunanih in izmerjenih vrednosti je dobro. S predlaganim eksperimentalnim pristopom so ob koncu naloge določene še magnetno nelinearne karakteristike magnetnih sklepov, s pomočjo katerih smo opazovali vplive magnetne sklopljenosti stroja
Napredno vodenje sistema za uporovno točkasto varjenje : doktorska disertacija by Beno Klopčič( Book )

1 edition published in 2007 in Slovenian and held by 3 WorldCat member libraries worldwide

The thesis describes the DC current source used for the resistance spot welding sy-stem. The welding system consists of the rectifier, and the transistor inverter that converts the DC voltage to the AC voltage. The inverter operates at the middle frequency range. The obtained AC voltage represents the transformer primary rail supply white the transformer secondary coil is connected to the full wave rectifier which finally supplies the welding clamps. The welds produced by the resistance spot welding system must be of high quality while the operation speed of the sy-stem should be as high as possible. The transformer, the full wave rectifier, and the welding clamps are usually mounted directly to the robotic afm therefore the lower dimension/mass allow its faster moves. The systematic analysis of the welding system with the classical pulse width modulation control, explained some phenomena which preclude the optimal use of the system. An electrically non-symmetrical output of the welding system controlled by the classical control always causes an increasing offset in flux density B, which provokes high magnetic saturation of the transformer iran core. The transformer iran core is therefore very poorly exploited. The result s of systematic numeric analysis of the welding system which explained the reasons for very bad exploitation of the transformer iran core and bad behavior of the system are confirmed by measurements. The relatively simple passive solu-tion is proposed to eliminate saturation white the exploitation of the iron core still remains very poor. The proposed advanced control of the resistance spot welding system provides the active solution to the stated problem. In this case the system operation is based on the real time measurement s of the magnetic properties of the used transformer. The advanced control system simultaneously controls the degree of saturation of the transformer iran core and the welding current, which allows the use of a smaller transformer core. The advanced control assures the best possible exploitation of the transformers' iran core. THe switching frequency of the inverter and corresponding switching losses can be reduced on average with the proper selection of current controller settings. The advanced control system was numerically and experimentally tested with the excellent match of the obtained results. Due to the benefits it provides, the advanced control of the resistance spot welding system will be protected by the patent
Obravnava trifaznih sistemov s pomočjo vektorskih prostorov : doktorska disertacija by Gorazd Štumberger( Book )

1 edition published in 1996 in Slovenian and held by 3 WorldCat member libraries worldwide

The treatment of poly-phase systems based on the formalism of vector spaces is described. The currents and the voltages of a poly-phase system are presented by the instantaneous values, continuous functions and sequences of sampled values. In all of the three current and voltage representations the poly-phase system is introduced as an Euclidean vector space in which the norm and the inner product are defined. The definitions of power and projections are gvien on the level of the Euclidean sapce. The formalism of vector is spaces is used to discuss the single-, two- and three-phase systems. The established electrical engineering treatment and the treatment based on the formalism of vector spaces agree perfectly only in the case of a single-phase system in which the current and the voltage are harmonic functions of the fundamental frequency. Different bases are introduced in the three-phase system for all of the three current and voltage representations. In electrical engineering, the relations between the base vectors of different bases are determined by the known transformation matrices which give the relation between the coordinates of the same vector in different bases. The subspaces of phases and harmonic components are introduced. The norms of projections on the selected subspaces make it possible to assess the content of individual harmonic components in the currents and volatges of individual phases, as well as in the voltages of the three-phase system as a whole. The definitions of norms in vector spaces are not unique. The meaning of some of the most important norm is explained on the example of a two-phase and a three-phase system. Vector spaces make it possible to discuss any poly-phase system in any kind of operating conditions. It is particularly interesting to use them for the treatment of transients in poly-phase systems, in poly-phase systems with higher harmonic components, and whenever the established electrical engineering approach offers no acceptable solution. The treatment of three-phase systems using vector spaces can also be used in the design of protection algorithms for power system elements and in the minimization of power transmission losses. Two examples of using vector spaces are presented: in the design of the power transformer algorithm and in the compensation of transmission losses without energy storage. The use of vector spaces in power transformer protection offers many new approaches. The orthogonal decomposition of vectors of the primary and the secondary current enables a separate treatment of ground- and other faults, which improves the selectivity of the protection algorithm. The use of Euclidean norms upgrades the sensitivity of the protection algorithm
Computer Networking Symposium : proceedings, December 11, 1984, National Bureau of Standards, Gaithersburg, Maryland : a symposium by Euromicro( Book )

1 edition published in 2002 in English and held by 3 WorldCat member libraries worldwide

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Določanje parametrov nelinearnih modelov kaplanove turbine z diferenčno evolucijo : doktorska disertacija by Dalibor Kranjčič( Book )

1 edition published in 2014 in Slovenian and held by 3 WorldCat member libraries worldwide

This doctoral dissertation describes development and identification of new models of double-regulated Kaplan turbines suitable for use in power system stability studies. Also it gives a detailed overview of the existing single and double regulated turbine models presented in scientific literature. The models are developed according to new concept called "virtual gate opening" (VOP). In this concept, the double-regulated turbine model is obtained as an extension of the nonlinear single-regulated turbine model through an approximation function that defines the relationship between the wicket gate opening and runner blades angle. The parameters of the approximation function are determined in the identification procedure using the VOP concept-based dynamic model, empirically determined differential evolution algorithm-based methods, field measurement data acquired during normal operating conditions and turbine characteristics data. Various types of surfaces used in the field of computer aided geometric design (CAGD) are applied for structure of the approximation function. The dissertation focuses on progressive development of differential evolution algorithm-based methods that are applied to determine different forms of the approximation functions, until an optimal form is attained that ensures the best possible agreement between the measured and calculated responses
Optimalno sledenje fotonapetostnega sistema soncu ob upoštevanju izgub pogonskega sklopa : doktorska disertacija by Sebastijan Seme( Book )

1 edition published in 2011 in Slovenian and held by 3 WorldCat member libraries worldwide

Doctoral thesis deals with optimal sun-tracking of a photovoltaic system considering the electric drive losses. The Sun tracking PV system assures that the highest possible share of the available solar radiation reaches the surface of the PV modules. The electric drive which enables tracking is considered as the loss of the energy produced in the PV system. The maximum of the energy produced in the PV system is achieved by the continuous tracking of the PV system. Since the electric drives are determined by constant speed and time, and angle quantization the maximum of the energy produced can only approximate. The doctoral thesis presents a new method for determining such trajectories of the PV modules that change the position of the PV modules in such a way that the production of the electric energy in the given time interval of the observation reaches its maximum. The goal is to determine the maximum efficiency of the PV tracking system considering the tracking system energy consumption. To achieve this, exact values of the available solar energy are needed for a given moment. To do this, a new method for predicting direct and diffuse solar radiation on the Earthćs surface, in the form of the time dependent function, is developed. The method is confirmed by the comparison of the measured and the predicted solar radiation for clear days. The developed method for predicting the solar radiation in the form of the time dependent function and energy consumption of the tracking system, given as the functions of the azimuth and tilt angle change, are applied together to determine those trajectories of the PV module, where the PV system energy production, gives the maximum. To find a solution of the nonlinear and bounded optimization problem, a stochastic search algorithm called DifferentialEvolution is applied. The approach for determining the maximum of the energy produced in the PV system has not been researched yet. The explicitly defined objective function, which is minimized in the optimization procedure considering the optimization bounds, is used. Thus it is assured the maximum of the possible energy produced in the PV system, considering the applied model of the PV system, tracking system consumption, predicted solar radiation, and the properties of the applied optimization method. The use of the different and more advanced models of the PV system, the sun tracking system consumption or prediction of the solar radiation, can lead to the different optimal trajectories of the sun tracking system. However, this cannot reduce the importance of the proposed method. The proposed method gives the maximum of the possible energy produced in the discussed PV system, considering the applied models and data
Algoritem za celostno vrednotenje fotovoltaičnega in vetrnega potenciala večjih geografskih območij : doktorska disertacija by Niko Lukač( Book )

1 edition published in 2016 in Slovenian and held by 3 WorldCat member libraries worldwide

In this doctoral dissertation, a new algorithm is proposed for the estimation of photovoltaic and wind potential over large area, which is represented with a topological grid structure that is constructed from high-resolution laser-scanned LiDAR data. At first, the position of the Sun relative to the geographic location is calculated, as well as shadowing and anisotropic irradiance, by considering multiannual measurements of direct and diffuse irradiance. Calculated instantaneous global irradiance is integrated with respect to time using the global irradiance-dependent nonlinear efficiency characteristics of a given photovoltaic system. In the second part of the dissertation, a new methodology is presented for the estimation of wind potential over the constructed topological grid, in which the computer simulation of wind flow represented as clusters of air molecules is performed by using the Lagrangian method of smoothed particle hydrodynamics and Reynolds averaged turbulence model. In order to implement the estimation of wind flow, multiannual meteorological measurements of the wind velocity and direction are also considered, which are then used for constructing logarithmic wind profile that defines the initial conditions of the wind particles. In order to calculate the output power the nonlinear characteristics of wind systems are used, which depend on the calculated wind velocities. The calculated power values can then be integrated with respect to time in order to forecast electrical energy production. Both methodologies are merged into the proposed algorithm, which we implement on a graphics processing unit using CUDA technology, in order to perform the calculations in an acceptable time. Within the experimental part of the doctoral thesis, the accuracy of the calculation based on the input data is evaluated by comparing the calculated values with independent measurements. The proposed algorithm was also applied over the large geographical area of Maribor, in order to estimate its photovoltaic and wind potentials. The estimated photovoltaic potential has an agreement In this doctoral dissertation, a new algorithm is proposed for the estimation of photovoltaic and wind potential over large area, which is represented with a topological grid structure that is constructed from high-resolution laser-scanned LiDAR data. At first, the position of the Sun relative to the geographic location is calculated, as well as shadowing and anisotropic irradiance, by considering multiannual measurements of direct and diffuse irradiance. Calculated instantaneous global irradiance is integrated with respect to time using the global irradiance-dependent nonlinear efficiency characteristics of a given photovoltaic system. In the second part of the dissertation, a new methodology is presented for the estimation of wind potential over the constructed topological grid, in which the computer simulation of wind flow represented as clusters of air molecules is performed by using the Lagrangian method of smoothed particle hydrodynamics and Reynolds averaged turbulence model. In order to implement the estimation of wind flow, multiannual meteorological measurements of the wind velocity and direction are also considered, which are then used for constructing logarithmic wind profile that defines the initial conditions of the wind particles. In order to calculate the output power the nonlinear characteristics of wind systems are used, which depend on the calculated wind velocities. The calculated power values can then be integrated with respect to time in order to forecast electrical energy production. Both methodologies are merged into the proposed algorithm, which we implement on a graphics processing unit using CUDA technology, in order to perform the calculations in an acceptable time. Within the experimental part of the doctoral thesis, the accuracy of the calculation based on the input data is evaluated by comparing the calculated values with independent measurements. The proposed algorithm was also applied over the large geographical area of Maribor, in order to estimate its photovoltaic and wind potentials. The estimated photovoltaic potential has an agreement of 97%, while the agreement of the estimated wind potential is 92%.of the estimated wind potential is 92%
Univerza v Mariboru Fakulteta za elektrotehniko, računalništvo in informatiko : --- skozi čas in prostor --- by računalništvo in informatiko (Maribor) Fakulteta za elektrotehniko( Book )

1 edition published in 2015 in Slovenian and held by 3 WorldCat member libraries worldwide

Model železnega jedra transformatorja za uporovno točkasto varjenje : doktorska disertacija by Vojko Podlogar( Book )

1 edition published in 2012 in Slovenian and held by 3 WorldCat member libraries worldwide

Disertacija obravnava model železnega C jedra transformatorja za uporovno točkasto varjenje. Predstavljen je nov model C jedra, ki upošteva vplive vrtinčnih tokov na razporeditev magnetnega polja v jedru ter nelinearno magnetilno karakteristiko pločevine s histerezo. Model izhaja iz predpostavke,da se domensko strukturo magnetno usmerjene pločevine v jedru transformatorja lahko obravnava s klasičnim modelom pločevine, ki predvideva homogeno magnetno strukturo pločevine brez domen. Vpliv vrtinčnega toka na razporeditev magnetnega polja v pločevini smo upoštevali z navidezno razdelitvijo pločevine na tanke rezine, znotraj katerih je vpliv lastnega vrtinčnega toka rezine na razporeditev magnetnega polja v rezini tako majhen, da je upravičena predpostavka o homogenem magnetnem polju znotraj rezine. Za homogeno magnetno polje smo s pomočjo Amperovega in Faradayevega zakona za vsako rezino v pločevini dobili magnetno napetostno ravnotežno enačbo. V magnetni napetostni ravnotežni enačbi nastopa tudi nelinearna magnetilna karakteristika magnetnega materiala s histerezo, ki smo jo modelirali s skalarnim modelom histereze. Skupne izgube v jedru smo izračunali kot vsoto histereznih izgub in joulskih izgub zaradi vrtinčnih tokov v jedru. Preizkus je pokazal, da je zaradi upoštevanja vpliva vrtinčnih tokov v jedru transformatorja na razporeditev magnetnega polja v jedru razlika med izmerjenimi izgubami in z modelom izračunanimi izgubami tako majhna, da tako imenovanih presežnih izgub v jedru ni potrebno upoštevati. Razviti model železnega jedra transformatorja je enostavno vključiti v vezni model transformatorja. Model je uporaben za numerično analizo vodenja sistema za uporovno točkasto varjenje, ker pa so v modelu dimenzije jedra in pločevine ter električne in magnetne lastnosti pločevine podane parametrično, je model primeren tudi za optimizacijo dimenzij jedra transformatorja, debeline pločevine in izbiro materiala, iz katerega je narejena pločevina
Optimalna razporeditev vodnikov daljnovoda glede na emisije elektromagnetnih polj in hrupa : doktorska disertacija by Klemen Deželak( Book )

1 edition published in 2011 in Slovenian and held by 3 WorldCat member libraries worldwide

V Sloveniji je pridobivanje novih koridorjev za daljnovode zelo oteženo, če že ne skoraj onemogočeno. Zaradi velikega odpora javnosti do gradnje novih daljnovodov je potrebno vložiti mnogo truda tako v prostorsko načrtovanje daljnovodov, kakor v vrednotenje obremenitve okolja povzročene s strani daljnovoda. Pri tem morejo biti, znotraj danega koridorja, vplivi daljnovoda na okolje v okviru zakonsko predpisanih mej. Pri tem so zelo pomembne predvsem vrednosti emisij električne poljske jakosti, emisij gostote magnetnega pretoka ter emisij hrupa. Slednje so odvisne od napetosti voda, toka v vodu in geometrijske razporeditve vodnikov. Z ustrezno razporeditvijo vodnikov je mogoče v znatni meri vplivati na vrednosti emisij elektromagnetnih polj in hrupa v bližini koridorja daljnovoda. Še več, z ustreznimi programskimi orodji je za določen koridor mogoče določiti optimalen razpored vodnikov glede na dano kriterijsko funkcijo. Za določitev optimalnega razporeda vodnikov je v disertaciji razvito ustrezno optimizacijsko okolje. To obsega modul za določitev gostote magnetnega pretoka in električne poljske jakosti v poljubni točki vzdolž trase daljnovoda, z ali brez upoštevanja povesne verižnice. Dodatno je vključen tudi modul za izračun emisij hrupa daljnovoda in ustrezno optimizacijsko orodje. Cilj disertacije je poiskati optimalno razporeditev vodnikov trifaznega daljnovoda glede na dopustne vrednosti emisij elektromagnetnih polj in hrupa vzdolž koridorja, oziroma glede na izbrano kriterijsko funkcijo na takšen način, da bo višina vpetja strelovodne vrvi in s tem tudi višina stebra čim nižja. Rezultat disertacije je opis algoritmov za določitev optimalne porazdelitve vodnikov trifaznega daljnovoda glede na dano kriterijsko funkcijo in dane omejitve. Razvita programska orodja je mogoče uporabiti tudi pri preverjanju, ali je visokonapetostne daljnovode nižjih napetostnih nivojev mogoče, znotraj obstoječe trase, nadgraditi tako, da bodo primerni za višji napetostni nivo. Razen tega je razvito programsko orodje mogoče uporabiti za snovanje novih daljnovodov ob upoštevanju omejitev, ki so za izbrani napetostni nivo običajno podane v obliki širine koridorja in dopustnih vrednosti emisij elektromagnetnih polj in hrupa ter varnostnih razdalj in oddaljenosti
 
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