Systematic development of equivalent circuits for synchronous machines.

Imperial Users onl

Application of HPC in eddy current electromagnetic problem solution

As engineering problems are becoming more and more advanced, the size of an average model solved by partial differential equations is rapidly growing and, in order to keep simulation times within reasonable bounds, both faster computers and more efficient software implementations are needed. In the first part of this thesis, the full potential of simulation software has been exploited through high performance parallel computing techniques. In particular, the simulation of induction heating processes is accomplished within reasonable solution times, by implementing different parallel direct solvers for large sparse linear system, in the solution process of a commercial software. The performance of such library on shared memory systems has been remarkably improved by implementing a multithreaded version of MUMPS (MUltifrontal Massively Parallel Solver) library, which have been tested on benchmark matrices arising from typical induction heating process simulations. A new multithreading approach and a low rank approximation technique have been implemented and developed by MUMPS team in Lyon and Toulouse. In the context of a collaboration between MUMPS team and DII-University of Padova, a preliminary version of such functionalities could be tested on induction heating benchmark problems, and a substantial reduction of the computational cost and memory requirements could be achieved. In the second part of this thesis, some examples of design methodology by virtual prototyping have been described. Complex multiphysics simulations involving electromagnetic, circuital, thermal and mechanical problems have been performed by exploiting parallel solvers, as developed in the first part of this thesis. Finally, multiobjective stochastic optimization algorithms have been applied to multiphysics 3D model simulations in search of a set of improved induction heating device configurations

Interactions between polyhedral permanent magnets

With the current trend toward industrial automation, efficient energy generation, and electric motor vehicles, permanent magnets are seeing more widespread use than ever before. They permeate our world, enabling sound generation through loudspeakers, mass data storage in the server farms keeping us online, and even the vibration motors in our pockets notifying us of new messages. Never before have permanent magnets seen such widespread use, and thus it is paramount to understand the interactions between them. The primary aim of this thesis is to investigate and model the magnetic fields produced by generalised polyhedral permanent magnets, and the forces and torques between them. To achieve this aim, two main objectives were identified. The first objective was to analytically solve the magnetic charge model field equations for arbitrary polyhedral permanent magnets with a relative permeability of unity. This was performed using two unique approaches, leading to two unique but equivalent sets of field solutions, with the first being more effective when the field is calculated at few points, and the second being more effective when the field is calculated at many points. These field solutions were implemented in MATLAB code with a focus on computation efficiency, thus reducing calculation time. The solutions may also be used to numerically integrate over the surface of another magnet to accurately estimate the force and torque imparted. The second objective was to derive a methodology to model the field due to a polyhedral permanent magnet with non-unity relative permeability. This was done by applying a surface mesh to a magnet, and allowing the ‘magnetic charge’ on each surface element to vary based on the permeability and magnetic field passing through the element. This was derived in such a way that the field is calculated only once, with no iteration required. Rather, a matrix equation is solved to give the surface charge distribution, leading to calculations of the magnetic fields, forces, and torques based on the previous objective. This was again implemented in MATLAB code with focus on computation efficiency, leading to fast calculations. This thesis begins with a short prologue, giving a brief historical overview of the development of magnetism as a physical science. Chapter 1 follows, outlining the theory used for modelling magnets and giving a review of relevant literature. Chapters 2 and 3 outline two new methods for calculating the magnetic field produced by general ideal polyhedral permanent magnets, each with benefits and drawbacks over the other. In addition, Chapter 2 found that a pair of pyramid frustum magnets produce a larger mutual force than a pair of cuboidal magnets, suggesting further investigation into frustum magnets. Chapter 4 applies the methodology from Chapter 3 to a planar array of frustum magnets, finding no significant benefit over traditional cuboidal planar arrays. Chapter 5 explores magnetic permeability, deriving a methodology to calculate magnetic fields, forces, and torques imparted by linear magnetic materials of polyhedral geometry. Finally, the thesis is concluded in Chapter 6, summarising the preceding chapters and outlining potential future work to follow this thesis. The primary outcome of this thesis is the development of a new methodology which can accurately and quickly compute the magnetic fields, forces, and torques imparted by magnetic materials of polyhedral geometry. The methodology allows for materials with constant non-unity relative permeability, more accurately reflecting permanent magnet materials and magnetic behaviour. Moreover, other geometries may be accurately approximated by polyhedra and the methodology applied, allowing the fast and accurate approximation of any current-free magnetostatic system.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 202

Um estudo sobre métodos de determinação de estados e parâmetros de máquinas síncronas de polos salientes

Orientador: Mateus GiesbrechtDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: As máquinas síncronas de polos salientes desempenham um papel fundamental na análise de estabilidade de sistemas elétricos de potência, especialmente em países cuja maior parte da energia gerada provém de fontes hidráulicas. Os modelos elétricos equivalentes que descrevem o comportamento dessas máquinas são compostos por diversos parâmetros, os quais são utilizados em uma ampla gama de estudos. No presente trabalho, estudam-se e propõem-se técnicas de estimação de estados e parâmetros de máquinas síncronas de polos salientes. A princípio, as equações de tensão, de fluxos concatenados, de potência e de movimento são desenvolvidas com as devidas unidades de medida, tanto em variáveis de máquina quanto em variáveis projetadas sobre um plano ortogonal que gira na velocidade elétrica do rotor. Na maior parte da literatura, essas unidades não são explicitadas no equacionamento. Dentre os parâmetros elétricos dos modelos das máquinas síncronas de polos salientes, as reatâncias de magnetização são os que mais influenciam o comportamento da máquina em condições de regime permanente senoidal. Desta forma, apresenta-se uma nova abordagem à estimação do ângulo de carga dessas máquinas e o subsequente cálculo das reatâncias de magnetização a partir de condições de carga específicas -- o desempenho do método proposto é avaliado em dados de simulação e em dados reais de operação de um gerador síncrono de grande porte. Algumas abordagens à determinação de parâmetros requerem que a máquina seja posta fora de operação para que ensaios específicos possam ser realizados. Dentre eles, um dos mais empregados na determinação de parâmetros transitórios e de regime permanente é o ensaio de rejeição de carga; assim, este ensaio também é analisado e aperfeiçoado por um método automatizado de separação de soma de exponenciais baseado em projeção de variáveis. Por tratar-se de um sistema multivariável e altamente não linear, diferentes observadores de estado também são utilizados para se determinarem estados e parâmetros de máquinas síncronas em tempo hábil e com precisão satisfatória. Este trabalho apresenta uma abordagem não linear recursivamente aplicável à estimação de fluxos concatenados, correntes de enrolamentos amortecedores, ângulo de carga e reatâncias de magnetização de máquinas síncronas de polos salientes por meio da filtragem de partículas. Um modelo não linear de oitava ordem é considerado e apenas as medições realizadas nos terminais da armadura e do campo durante regime permanente se fazem necessárias para estimar as referidas grandezasAbstract: Salient-pole synchronous machines play a fundamental role in the stability analysis of electrical power systems, especially in countries where most of the generated energy comes from hydraulic sources. The electrical equivalent models that describe the behavior of these machines are composed of several electrical parameters, which are used in a wide range of studies. In the present work, techniques for estimating states and parameters of salient-pole synchronous machines are studied and proposed. A priori, the voltage, flux linkage, power, and motion equations are developed with the appropriate units included, both in machine variables and in variables projected on an orthogonal plane rotating in the rotor's electrical speed. In most of the literature, these units are not explained in the equation process. Among the electrical parameters, the magnetizing reactances are the ones that most influence the machine behavior under transient and steady-state conditions. In this way, a new approach to estimate the load angle of these machines and the subsequent calculation of the magnetizing reactances from specific load conditions are presented -- the performance of the proposed method is evaluated by means of simulation data and by operating data of a large synchronous generator. Some approaches to determine parameters require the machine to be taken out of operation, so that specific tests may be performed. Among them, one of the most used to determine transient and steady-state parameters is the load rejection test; thus, this test is also analyzed and refined by an automated method based on variable projection for separating the resulting sum-of-exponentials. Since the machines are highly nonlinear, multivariate, dynamic systems, different state observers seek to solve the state estimation problem in a timely manner and with satisfactory accuracy. This work presents a nonlinear and recursive approach for the estimation of flux linkages per second, amortisseur winding currents, load angle, and magnetizing reactances of salient-pole synchronous machines by means of the particle filtering. An eighth-order nonlinear model is considered, and only measurements taken at the machine terminals are necessary to estimate these quantitiesMestradoAutomaçãoMestre em Engenharia Elétrica162015/2018-6CNPq

Improving the Generality of the Fictitious Magnetic Charge Approach to Computing Inductances in the Presence of Permeable Materials

In this paper we present an improvement to the fictitious magnetic charge approach to computing inductances in the presence of permeable materials. The improvement replaces integration over a "non-piercing" surface with a line integral and an efficient quadrature scheme. Eliminating the need to generate non-piercing surfaces substantially simplifies handling problems with general geometries of permeable materials. Computational results are presented to demonstrate the accuracy and versatility of the new method

Technology 2002: the Third National Technology Transfer Conference and Exposition, Volume 1

The proceedings from the conference are presented. The topics covered include the following: computer technology, advanced manufacturing, materials science, biotechnology, and electronics

Measurements, Models, Systems and Design

531 s.

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion