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Dissertationen zum Thema „High-speed electrical machine“
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1
La, Rocca Antonino. „Thermal analysis of a high speed electrical machine“. Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33156/.
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This work has analysed, designed, commissioned and validated the performance of a novel cooling system for an innovative high speed, three-phase synchronous permanent magnet machine designed for an aero-engine starter/generator with a power rating of 45 kW and maximum speed of 32,000 rpm. The cooling system designed consisted into inserting a 1 mm non-electrically conductive stator sleeve in the machine airgap, this separates the rotor region from the stationary components letting the rotor running dry at all times; the stator region can then be flooded with oil. Oil enters from one side of the machine through some radial openings impinging directly over the end-winding, it then flows through two rows of equally sized axial ducts located along the inner and outer diameter of the stator to give an even distribution of the coolant, and finally it flows over the surface of the rear end-winding and leaves the machine. The thermal modelling was carried out by the joint use of Computational Fluid Dynamics (CFD) and Lumped Parameter Thermal Network (LPTN); this allowed the investigation of heat transfer phenomena and the optimisation of the cooling design. CFD was primarily employed to investigate the fluid flow and to perform conjugate heat transfer analyses; these allowed the determination of heat transfer coefficients and the prediction of temperature distribution inside the machine. Thermal networks were developed to investigate the heat flow through machine components, to perform the design optimisation and to maximise overall machine performance. A thermal network was also developed by the author to investigate the heat transfer phenomena inside the bearing chambers. An experimental apparatus was designed and commissioned in order experimentally validate the thermal models developed. Temperatures, pressures and torque up to 20,000 rpm were recorded throughout the tests and data collected were compared to quantities predicted analytically and numerically. Maximum winding temperatures measured performing a short circuit test agree well with analytical and numerical prediction with a maximum difference of 10%; mechanical losses measured carrying out a no-load test agree well at speeds over 10,000 rpm with differences between 2 and 12%. Throughout tests, pressure drops were monitored across the machine and an agreement of 13% with prediction were achieved. Design improvements are also proposed to further enhance the cooling of stator slots and of rotor components.
2
Mwaba, Gomezyani. „Permanent Magnet Machine Topologies for high speed flywheels“. Thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5145.
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3
Di, Nardo Mauro. „Design of high speed synchronous reluctance machine“. Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43223/.
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This thesis describes the work done during the several stages of the design, analyse, manufacture and test of a high speed synchronous reluctance machine capable of delivering 5 kW at 80 krpm. In order to meet such demanding speed requirement, several multi-disciplinary design exercises have been carried out having different aims. First the influences of the speed-dependent limiting factors on the machine performance have been investigated by analytical methodologies. After the preliminary analytical design, the main challenges related with the structural and electromagnetic FE-based design refinements have been identified. A comparative study has been then presented with the purpose of identify the most effective rotor design approach in terms of performance of the final design and computational effort related for its achievement. Once the design strategy has been chosen, the advantages of considering rotor parametrization of increasing complexity are evaluated via a comparative study showing the results of several structural optimizations. This study indicated the optimal geometry to manufacture. Prior to the machine prototyping, the influence of the rotor manufacturing tolerance as well as the thermal limitations on the machine performance have been deeply analysed. Tests carried out on the prototype have essentially validated the proposed design approach. In addition, an investigative study aimed at identifying and understanding the reasons of the found discrepancy between the measured and expected performance is also reported.
4
Papini, Luca. „Performance calculation of high speed solid rotor induction machine“. Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52180/.
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Solid rotor induction machines are suitable for applications which require robustness, reliability and high rotational speed. A literature review of high speed technologies is initially presented. The current limitation and challenges are detailed based on a wide collection of data. The multi-physics aspect related with electrical machines for high speed applications are discussed providing a summary of the current state of the art. The main aim of the research was to develop a multi-physic computational environment for the design and analysis of solid rotor induction machines. The electromagnetic, thermal, structural and rotor dynamics models have been developed targeting reduced computational time and accurate predictions. Numerical techniques are proposed based on the discretisation of the computational domain. The different disciplines are linked together providing a flexible and powerful tool for the characterisation of solid rotor induction machine. Another objective was to investigate the impact of the rotor material on the electromagnetic performances of the machine. Finite Element simulation are used to account for the non linear magnetic properties. The impact on the equivalent circuit parameter is discussed and general criteria for material selection presented. Three dimensional finite element calculation are p erformed targeting the validation of the end region correction factor and select the rotor length. The performances of a 120 [kW]−25000 [rpm] solid rotor machine are compared with a caged rotor induction machine for waste heat recovery application.
5
Ng'onga, Maxas. „Design, analysis and prototyping of a high speed surface mounted permanent magnet machine“. Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29189.
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Over the recent years, there has been a rise in the demand for high speed and high power density machines for various applications in industry ranging from basic household power tools to the flight controls for aircrafts in the aerospace sector. This has also seen advancements in the power electronics and controls for these machines to deal with the large operating frequencies. The increase in demand for high speed machines has been driven by the industry’s requirement for cost reductions, higher robustness & higher efficiencies. This thesis aims to contribute knowledge to the design and development of a high-speed surface mounted permanent magnet machine. A numerical procedure for the detailed sizing of a high-speed surface mounted permanent magnet (SPM) machine is outlined in this dissertation. An analytical per phase model is formulated to examine the performance parameters of the machine. The analytical model is validated against results obtained from Ansys Electromagnetics Finite Element Analysis (FEA) software. The estimation of core losses in high-speed machines is also of critical importance during electromagnetic design. An immense amount of research has been conducted on the estimation of core losses in machines, however, not much has been done to cover the estimation of highspeed core losses as compared to the traditional low-speed machines. As part of the development of the high-speed machine, the numerical estimation of the highspeed core losses was examined and validation performed using FEA software. On average, there was a difference of about 3-11% between the analytical results and FEA results of the eddy current loss and hysteresis loss. These results demonstrate that the analytical method used to estimate core losses is reasonably accurate when compared to FEA results obtained from ANSYS Maxwell. The prototyping of a high-speed surface mounted permanent magnet machine is investigated. Focus is placed on the major components of the machine whilst highlighting the use of precision machining and the need to maintain high accuracy during manufacturing and assembly of the machine prototype.
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Grimes, Ryan T. „Design Of An Adjustable Sensing And Control Network For High Speed Product Packaging Machines“. University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1236086640.
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7
Jalili, Kamran. „Investigation of Control Concepts for High-Speed Induction Machine Drives and Grid Side Pulse-Width Modulation Voltage Source Converters“. Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A25053.
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Control of a low voltage ac/dc/ac converter for high-speed induction machine drive applications has been investigated. Such a configuration can be applied, for example, in microturbines and high-speed spindles.
Scalar control is usually applied for the control of high-speed drives especially in the case of very high-speed drives. Indirect rotor-flux-oriented control and direct torque control are designed and compared for the control of an exemplary high-speed induction machine drive.
The 2L VSC is the most widely applied converter for high-speed drives. However, the 3L-NPC VSC is an attractive topology if drastically increased switching frequencies are required. A detailed comparison between a 2L VSC and a 3L-NPC VSC as the machine side converter of the exemplary high-speed induction machine drive is carried out.
Voltage-oriented control is applied for the control of the grid side PWM active front end converter. In several industrial applications PWM active front end converters commonly operate in parallel to thyristor converter fed dc drives. Behavior of the voltage-oriented controlled active front end converter with L-filter in the presence of a parallel thyristor converter is investigated.
The design of the LCL-filter components according to the given maximum grid current harmonics (e.g. IEEE-519) is a complex task. So far a precise and clear design procedure has not been presented. A new procedure to design the grid side filter (L- and LCL-filter) is proposed using the analytical expression of the converter voltage harmonics based on Bessel functions to achieve the compliance with the grid standard of IEEE-519. Voltage-oriented control with active damping is used to control the active front end converter with LCL-filter. A simple method is proposed to design the required lead-lag compensator in the active damping loop.
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Jalili, Kamran. „Investigation of control concepts for high speed induction machine drives and grid side pulse width modulation voltage source converters“. Doctoral thesis, Berlin mbv, 2009. http://d-nb.info/995880107/04.
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9
Gerada, David. „High speed electrical machines for the more-electric engine“. Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659206.
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With the increasingly stringent emissions legislation as well as the hiking fuel prices, engine electrification is currently a prime path for automotive companies to meet the environmental and efficiency targets, thus placing the need for high-performance automotive electrical machines. This research looks at developing high-speed electrical machines for an electrically-assisted turbocharger to be used within Cummins' heavy duty diesel engines. While the potential benefits of such a system are high, integrating a high speed, high power-density electrical machine within the aggressive turbocharger environment is challenging. In this work detailed system multi-domain models which include the electromagnetic, thermal and mechanical aspects are developed. Using these models, together with knowledge of electrical machine material properties, the capabilities and limitations of different types of electrical machines for use in electrically-assisted turbo-charging are determined. The field weakening properties, robustness and relatively low-cost make the Induction Machine the preferred technology for the application. This work provides a set of design guidelines for maximising the power density of high speed Induction Machines. In particular moving away from the conventionally used round rotor-bar and tailoring the split-ratio together with tailoring the machine IS electrical and magnetic loadings are shown to be important aspects in increasing the power density. An algorithm for increasing the power-density of high-speed induction machines is presented. Design recommendations are also presented for PM machines where tailoring the air-gap length is identified and shown to be important in optimising the distribution of losses. A computationally-efficient PEA-based technique is developed for the analysis of closed rotor-slot IMs. The optimized 9.5kW, 50000rpm IM design is prototyped and experimental results compared to those predicted from analysis.
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Smith, Daniel James Bernard. „High speed high power electrical machines“. Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2645.
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High Speed High Power (HSHP) electrical machines push the limits of electromagnetics, material capabilities and construction techniques. In doing so they are able to match the power performance of high speed turbomachinery such as gas turbines, compressors and expanders. This makes them attractive options for direct coupling to such machinery as either a power source or as a generator; eliminating the need for gearboxes and achieving a smaller system size and greater reliability. The design of HSHP machines is a challenging, iterative process. Mechanical, electromagnetic and thermal constraints are all placed on the machine shape, topology, operating point and materials. The designer must balance all of these constraints to find a workable solution that is mechanically stable, can work within the available electrical supply and will not overheat. This thesis researches the fundamental origins and interaction of the mechanical, electromagnetic and thermal constraints on electrical machines. Particular attention was paid to improving the accuracy of traditional mechanical rotor design processes, and improving loss estimation in inverter fed machines. The issues of selecting an appropriate electric loading for low voltage machines and choosing effective, economic cooling strategies were explored in detail. An analytical iterative design process that combines mechanical, electromagnetic and thermal design is proposed; this process balances the need for speed versus accuracy for the initial design of a machine, with Finite Element Analysis used only for final validation of performance and losses. The design process was tested on the design and manufacture of a 1.1MW 30,000rpm PM dynamometer used in an industrial test stand. The machine operating point was chosen to meet a gap in the industrial machines market and exceed the capabilities of other commercially available machines of the same speed. The resulting machine was successfully tested and comfortably meets the performance criteria used in the design process.
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Hodgins, Neil. „High speed electrical power takeoff for oscillating water columns“. Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4642.
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This thesis describes research into electrical power takeoff mechanisms for Oscillating Water Column (OWC) wave energy devices. The OWC application is studied and possible alternatives to the existing Induction Generator (IG) are identified. The Permanent Magnet Generator (PMG) is found to be the most promising. Results showed that the IG could almost match the output of the PMG if it could be operated significantly above its rated capacity. This improvement would require only limited changes to the overall OWC system. The ability to operate overloaded is determined by the losses and cooling of the IG. The losses in a suitable IG were measured in tests at Nottingham University. Steady state measurements were made of the cooling ability of the OWC airflow at the LIMPET wave power plant operated by Wavegen (the sponsor company) on Islay. Thermal modelling combining the loss and cooling measurements allowed the maximum capacity of the induction generator in an OWC to be found. A simplified model that accurately represents this system is proposed for use in system design and generator control.
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Barnes, David Donn Sinclair. „Design of effective air cooling systems for high speed electrical machines“. Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/7955.
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13
Ou, Jing [Verfasser], und M. [Akademischer Betreuer] Doppelbauer. „Improving high-speed electrical machines by amorphous metals / Jing Ou ; Betreuer: M. Doppelbauer“. Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1202076645/34.
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14
Kalyan, Mohamedreza. „Comparison of interior permanent magnet synchronous machines for a high-speed application“. Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29442.
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Permanent Magnet machines have been increasingly used in high-speed applications due to the advantages they offer such as higher efficiency, output torque and, output power. This dissertation discusses the electrical and magnetic design of permanent magnet machines and the design and analysis of two 10 kW, 30000 rpm Interior Permanent Magnet (IPM) machines. This dissertation consists of two parts: the first part discusses high-speed machine topologies, and in particular the permanent magnet machine. Trends, advantages, disadvantages, recent developments, etc. are discussed and conclusions are made. The second part presents the design, analysis and testing of interior permanent magnet machines for a high-speed application. The machines are designed from first principles and are simulated using Ansys Maxwell software to understand the finite element analysis. In order to obtain a fair comparison between the machines, the required output criteria was used as the judging criteria (10kW, 30000 rpm). As a result, the rotor diameter, stator diameter, airgap length, and stack length were kept the same for both machines. The winding configuration was set as distributed windings, however the number of turns and other details were kept flexible in order to be able to obtain the best design for each machine. Similarly, the magnet volume was kept flexible as this could be used as a comparison criteria relating to the cost of the machines. The two IPM topologies are compared with respect to their torque, magnetic field, airgap flux, core loss, efficiency, and cost. The radial IPM produces a smoother torque output, with lower torque ripple, and has lower losses compared to the circumferential IPM which produces a higher torque and power output. Furthermore, the circumferential IPM also experiences much higher torque ripple and core losses, both of which are highly undesirable characteristics for high-speed machines. In addition, the circumferential IPM has a much more complex manufacturing process compared to the radial IPM which would significantly increase the cost of prototyping the machine, thus the radial IPM was selected for prototyping and brief experimental analysis. The radial IPM has been experimentally tested under no-load conditions. These results were successfully compared to the simulated and analytical results to show correlation between the design and experimental process. Potential areas of further work may include conducting detailed loss analysis to understand the effects that changing various design parameters has on the core loss and overall performance. Detailed thermal and mechanical analysis of the machines may also result in interesting conclusions that would alter the design of the machine to make it more efficient.
15
Irenji, Neamat Taghizadeh. „Calculation of electromagnetic rotor losses in high-speed permanent magnet machines“. Thesis, University of Southampton, 1998. https://eprints.soton.ac.uk/47948/.
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High-speed permanent magnet machines are currently being developed for a number of applications including gas-turbine generator sets and machine tools. Due to the high peripheral speed of the rotor and the relatively high conductivity of the magnets used, rotor eddy current loss can be substantial. Quite low levels of loss may present a serious problem if rotor cooling is poor. The accurate calculation of these losses, and appreciation of their dependence on machine parameters, are therefore of great importance for reasons of both efficiency and temperature rise. In this, thesis, a method has been developed to evaluate the asynchronously rotating harmonics with respect to the rotor and to calculate rotor power loss caused by these harmonics. The harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. The data is obtained from finite element magnetostatic analysis of the machine at different rotor positions, with all possible harmonic sources present, except rotor induced eddy currents whose effect on harmonics was found to be negligible. Rotor power loss is calculated for each harmonic using a 2D rectilinear current sheet model of the machine. The magnitude of the current sheet, which is placed on the inner surface of a toothless stator, is adjusted to produce the same magnetostatic normal flux density over the rotor surface as that of the corresponding harmonic. The 2D current sheet model does not allow for 3D end effects and magnet segmentation. The accuracy of the analytical rectilinear current sheet model was verified by comparison with a cylindrical FE current sheet model, and by solving a benchmark eddy current problem that can be also solved using FE steady-state AC analysis. The current sheet model was used to calculate rotor loss in a number of generic machines, with two basic types of rotor construction: 1) non-salient rotor with arc shaped surface magnets and 2) salient rotor with chord shaped surface magnets. The results show that rotor loss depends strongly on the ratio of slot opening to slot pitch (s/X.) and on the ratio of total airgap to slot pitch (g/X). For the same fundamental airgap flux density, rotor loss reduces dramatically by increasing airgap length and reducing slot opening. Increasing the number of slots also reduces the loss. The results also show that rotor loss in a generator increases as the power factor moves from lagging to leading due to the armature reaction effect. Using a conducting sleeve, instead of a non-conducting one, with conductivity in the range of practical values, increases rotor losses dramatically. Reducing magnet conductivity reduces rotor loss. Rotor power loss in machines with non-conducting sleeve is concentrated on the surface of the magnet and a small part on the surface of the hub. In machines with chord shaped magnets, the power loss density can be very high in the parts of the steel hub near the intersection of two poles where local total airgap is small. The harmonics caused by inverter switching in a motor or rectifier switching in an alternator can cause a very significant increase in rotor loss, compared to a machine with a sinusoidal mmf. The results also show that the loss depends strongly on the switching strategy, e.g., switching harmonics in 6 step mmf waveform produce 3 times more loss than a 12 step mmf waveform. Although the developed method for calculation of rotor power loss does not take the effect of magnet peripheral discontinuity or segmentation into account, it is clear that segmentation reduces power loss by interrupting the eddy current return path, specially for harmonics with long wavelengths. The effect of segmentation requires further study.
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Bílek, Vladimír. „Elektromagnetická analýza a modelování asynchronního stroje s plným rotorem“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442791.
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Tato diplomová práce se zabývá elektromagnetickou analýzou a modelováním asynchronního stroje s plným rotorem. Tato práce tedy zahrnuje literární rešerši na téma vysokootáčkových elektrických strojů s porovnáním s klasickými elektrickými stroji s převodovkou a popisem jejich výhod či nevýhod, rozdělení vysokootáčkových elektrických strojů s plnými rotory a srovnání jejich výhod či nevýhod, kde se tato práce nejvíce soustřeďuje na vysokootáčkové asynchronní stroje s plnými rotory a jejich použití v průmyslu. Dále se tato práce zabývá metodami výpočtu elektrických asynchronních strojů s plnými rotory. Proto jsou zde uvedeny a popsány metody výpočtu stroje mezi které patří analytické metody i metoda konečných prvků. Vzhledem k povaze elektrických strojů s plnými rotory je hlavně kladen důraz v této práci na výpočet stroje pomocí metody konečných prvků ve 2D prostoru s využitím korekčních činitelů konců plných rotorů, které jsou zde velmi detailně popsány a rozděleny. Na základě dostupné literatury je vypočítaný elektrický stroj s plným rotorem pomocí MKP analýzy. Elektromagnetický výpočet stroje je automatizován pomocí skriptu vytvořeného v Pythonu. Dalším hlavním cílem této práce je popis tzv. náhradních modelů, uvedení jejich výhod či nevýhod, použití v jiných průmyslových odvětvích a hlavně použití náhradních modelů na elektrický stroj s plným rotorem. S využitím náhradních modelů je dále optimalizovaný vybraný asynchronní stroj s plným rotorem a to pomocí programů SymSpace a Optimizer. Pro samotnou optimalizaci byly uvažovány 3 návrhy stroje, které byly na závěr mezi sebou porovnány a to hlavně z hlediska jejich elektromagnetického výkonu.
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Bárta, Jan. „Návrh elektrického stroje 6 kW, 120 000 ot/min pro turbo-cirkulátor hélia“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-369739.
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The induction machine with a squirrel cage is a workhorse of the industry. The main advantage of an induction machine is the low manufacturing price, simple and robust construction, low maintenance requirements. However, for high-speed applications, induction machine with a squirrel cage requires design modification due to the mechanical restrictions. The objective of this thesis is to show design process, methodology and assembly of the induction machine for high-speed applications. In this thesis, the rotor dimensioning data are presented. The results are demonstrated on the design of the 6 kW, 120 000 rpm solid rotor squirrel cage induction machine. This thesis also contains calculation and design of three different electrical machine topologies for a turbo circulator application. The electrical machines are designed with 6 kW output power at 120 000 rpm. The machines are estimated by using electromagnetic, thermal, and mechanical calculations. The drawbacks and advantages of each topology under study are described. For other high-speed applications, a comparative method helps in choosing the suitable electrical machine topology by examinations of discussed criteria. Rotor design effect on the electromagnetic performance of the induction machine is shown. Mechanical stresses are calculated with Finite Element Method analysis. Various assembly technologies to produce solid rotor with squirrel cage are discuss and compare. Describe approach enables high electromagnetic performance and durable construction of the high-speed induction machine. Work is confirmed by measurement on the manufactured prototype.
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Zheng, Liping. „SUPER HIGH-SPEED MINIATURIZED PERMANENT MAGNET SYNCHRONOUS MOTOR“. Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3552.
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This dissertation is concerned with the design of permanent magnet synchronous motors (PMSM) to operate at super-high speed with high efficiency. The designed and fabricated PMSM was successfully tested to run upto 210,000 rpm The designed PMSM has 2000 W shaft output power at 200,000 rpm and at the cryogenic temperature of 77 K. The test results showed the motor to have an efficiency reaching above 92%. This achieved efficiency indicated a significant improvement compared to commercial motors with similar ratings. This dissertation first discusses the basic concept of electrical machines. After that, the modeling of PMSM for dynamic simulation is provided. Particular design strategies have to be adopted for super-high speed applications since motor losses assume a key role in the motor drive performance limit. The considerations of the PMSM structure for cryogenic applications are also discussed. It is shown that slotless structure with multi-strand Litz-wire is favorable for super-high speeds and cryogenic applications. The design, simulation, and test of a single-sided axial flux pancake PMSM is presented. The advantages and disadvantages of this kind of structure are discussed, and further improvements are suggested and some have been verified by experiments. The methodologies of designing super high-speed motors are provided in details. Based on these methodologies, a super high-speed radial-flux PMSM was designed and fabricated. The designed PMSM meets our expectation and the tested results agree with the design specifications. 2-D and 3-D modeling of the complicated PMSM structure for the electromagnetic numerical simulations of motor performance and parameters such as phase inductors, core losses, rotor eddy current loss, torque, and induced electromotive force (back-EMF) are also presented in detail in this dissertation. Some mechanical issues such as thermal analysis, bearing pre-load, rotor stress analysis, and rotor dynamics analysis are also discussed. Different control schemes are presented and suitable control schemes for super high- speed PMSM are also discussed in detail.Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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Krøvel, Øystein. „Design of Large Permanent Magnetized Synchronous Electric Machines : Low Speed, High Torque Machiines - Gererator for Diriect Driven Wind Turbine- Motor for Rim Driven Thruster“. Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12417.
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This work presents the design of two prototype permanent magnetized electric machines for two different applications where large permanent magnet machines might be used. Existing technology have been used as the fundament for new design and adapted to new applications, contributing, hopefully, to the development of better and more environmental friendly energy conversion. The first application presented is represented with a prototype made in cooperation with the industry in which a PM-motor is integrated into a propeller unit. Both because of the industrial connection, and the integration between the PM-motor and the propeller, the choices made for the PM-motor are conservative trying to reduce the risk. The direct rim driven thruster prototype includes a surface mounted radial flux permanent magnet machine (SM RFPM) with fractional slot winding with a q around 1. Other engineering features were introduced to make the integration of propeller and motor feasible, but without the PM-machine the thruster would not have reached the performance demand. An important part of the project was to show that the SM RFPM enables this solution, providing high performance with a large air gap. The prototype has been tested in sea, under harsh conditions, and even though the magnets have been exposed directly to sea water and been visible corroded, the electric motor still performs well within the specifications. The second application is represented with a prototype PM-generator for wind turbines. This is an example of a new, very low speed high torque machine. The generator is built to test phenomena regarding concentrated coils, and as opposed to the first application, being a pure academic university project, its success is not connected to its performance, but with the prototype’s ability to expose the phenomena in question. The prototype, or laboratory model, of the generator for direct driven wind turbines features SM RFPM with concentrated coils (CC). An opportunity to push the limits for the design was given, and taken, choosing a relative high frequency and open slots to investigate the consequences of large reluctance variations in the air gap and distorted MMF. The main purpose of the PM generator is to explore a very low speed machine with high pole number and concentrated coils with coils wound around every other tooth. The study leading to the design included a discussion of scaling of the prototype from the full size generator, which parameters to keep, which to stress and which to forget. An investigation of the winding layout and winding factors included building a smaller table model for testing of different winding configurations, was also an important part of the work. Though the prototype has its flaws, or experimental setbacks, it successfully enhances the characteristic of the low speed, high pole number and slot geometry focusing on the harmonic content of the MMF and the consequences for the losses and reactance.
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Treurnicht, N. F. „High speed cutting and electric discharge machining as complementary processes in the die and mould industry“. Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53448.
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Thesis (MScEng) -- Stellenbosch University, 2003.ENGLISH ABSTRACT: High Speed Cutting (HSC), specifically milling is a significant contemporary development in machining. The Die and Mould industry is experiencing a difficult business climate. There is competitive pressure for shorter lead times and lower prices. Companies worldwide, are under financial pressure, to meet the challenges of a globalised business environment. The conventional position of milling and Electric Discharge Machining (EDM / Erosion) is discussed with the proposal to use HSC and EDM as complementary processes. Among new developments the progress in computer infrastructure is prominent. There is also a paradigm shift that should be made from experience based process planning to modern, up to date knowledge based process planning. High Speed Cutting is now a mature process capable of acceptable process security. The examples detailed include crankshaft-forging tooling, injection moulding tooling and powder sintering tooling. A process chain is proposed for the complementary HSC / EDM process with estimated illustrative time saving over the conventional EDM dominated process. HSC will be the first process removing the bulk of the material, finishing as far as possible and with EDM finally machining the features that will be difficult or impossible with HSC. To facilitate the use of the complementary processes a decision model to determine the crossover point between HSC and EDM is proposed. The decision model is firstly presented as a flow diagram to determine whether the task is a candidate for HSC only, EDM only, or the complementary HSC / EDM process. The key parameters e.g tool H d ratio are variables. This is in order that the flow diagram may be adapted to a specific machine tool infrastructure and expertise level in a company. The second part is a HSC machining time estimation model. The time is estimated per segment roughed, semi-finished, or finish machined. The model is in an empirical form with constants that can be adapted to the practices of a specific company. It is intended that the constants also be periodically revised to reflect the development in HSC expertise that will occur during the use HSC in the company. The model is practically evaluated with a case study, including the detail steps, not included in the model. Conceptual guidelines are given for software implementation. It is concluded that HSC and EDM are suitable complementary processes. It is a necessary prerequisite to use pallets to avoid multiple set-ups. Complementary HSC and EDM is especially appropriate for the gradual deployment and skill development for HSC. HSC and complementary HSC / EDM is considered the opportunity for companies to make a major breakthrough in lead time and operating expense if the necessary pallet/fixturing equipment, CAx infrastructure and human capability is available.
AFRIKAANSE OPSOMMING: Hoe Spoed Masjinering (HSC), spesifiek frees is ‘n betekenisvolle ontwikkeling in masjinering. Die Gereedskap en Gietvorm bedryf ervaar ‘n moelike besigheidsklimaat. Daar is kompeterende druk vir korter lewertye en laer pryse. Maatskappye wereldwyd is onder finansiele druk om in die geglobaliseerde besigheidsmilieu te presteer. Die posisie van frees en Elektriese Ontladingsmasjinering (EDM / Vonkerosie) word bespreek met die voorstel om HSC en EDM as komplementere prosesse te gebruik. Onder die nuwe ontwikkelings is daar prominente vooruitgang in rekenaarinfrastruktuur. Daar is ook ‘n paradigmaverskuiwing nodig van ondervinding gebaseerde na op datum kennis gebaseerde proses beplanning. HSC is nou ‘n ontwikkelde proses met voldoende prosessekerheid. Die voorbeelde sluit krukas smee gereedskap, inspuitgiet gereedskap, en poeier-sinter persgereedskap in. ‘n Prosesketting word voorgestel vir die komplementere HSC / EDM proses met ‘n beraamde illustratiewe tydbesparing oor die konvensionele EDM gedomineerde proses. HSC sal die eerste proses wees wat die meerderheid van die materiaal verwyder en oppervlaktes so ver as moontlik afwerk, met EDM wat die finale afwerking doen en ook die masjinering wat vir moeilik haalbaar of onmoontlik is vir HSC. Om die gebruik van die komplementere prosesse te fasiliteer, word ‘n beluitnemingsmodel vir die oorgangspunt tussen HSC en EDM voorgestel. Dit word eerstens as vloeidiagram gebruik om die taak te klassifiseer vir HSC alleen, EDM alleen of vir komplementere HSC en EDM. Die sleutelparameters, bv die beitel 116 verhouding, is veranderlikes. Dit is sodat die vloeidiagram aangepas kan word by ‘n spesifieke masjienvermoe en ‘n kundigheidsvlak in ‘n maatskappy. Die tweede deel is ‘n HSC masjineringstyd model. Die tyd word beraam per segment uitgerof, afgewerk, of finaal afgewerk. Die model is in empiriese vorm met konstantes wat kan aangepas word by die praktyke van ‘n firma. Dit is die bedoeling dat die konstantes periodiek aangepas word om die ontwikkeling te weerspieel wat in die maatskappy plaasvind. Die model word prakties evalueer met ‘n gevallestudie, insluitend die detailstappe, wat nie in die modelformulering ingesluit is nie. Konseptuele riglyne word gegee vir programmatuur implementering. Die gevolgtrekking word gemaak dat HSC en EDM geskikte komplementere prosesse is. Dit is ‘n voorvereiste om pallette te gebruik om veelvuldige opstellings te vermy. Komplementere HSC / EDM is veral toepaslik om HSC geleidelik in ‘n firma te ontplooi en kundigheid te bou. Die HSC / EDM kombinasie word ook die geleentheid geag vir firmas om ‘n deurbraak te maak in lewertyd en bedryfsuitgawes as die nodige pallettoerusting, CAx infrastruktuur en menslike vermoe beskikbaar is.
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O'Leary, Beth Andrews. „Analysis of high-speed rotating systems using Timoshenko beam theory in conjunction with the transfer matrix method /“. Online version of thesis, 1989. http://hdl.handle.net/1850/10608.
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Bezombes, Frédéric. „Fibre Bragg grating temperature sensors for high-speed machining applications“. Thesis, Liverpool John Moores University, 2004. http://researchonline.ljmu.ac.uk/5630/.
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In high-speed grinding research, it is required to measure temperature within the workpiece. Present techniques are thermocouple based, and often suffer from excessive electrical noise on the signal. This thesis presents a number of novel and existing optical sensing devices that overcome this limitation and also, in some cases, offer greater performance. The optical sensors are fibre Bragg grating based and the optical techniques used to interrogate that sensor include DWDM, WDM, athermic grating, tuneable grating and coupler. Optical fibre devices are simpler to place in situ prior to the machining tests and they offer faster response and greater sensitivity than was previously possible. Results are presented from machining tests and the new devices are compared with each other and thermocouple based techniques. A method to relate internal measured temperature to machined surface temperature is also demonstrated in the context of high-speed machining.
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Qazalbash, Arfakhshand. „Rotor eddy current power losses in high speed permanent magnet synchronous generators“. Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/364580/.
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Rotor electromagnetic losses can be problematic in high speed permanent magnet synchronous machines, especially when the speed or the electrical loading are high and the slotting and winding configuration results in high magnitude asynchronous harmonics. Accurate estimation of these travelling flux harmonics in the initial design stage is essential, as small errors can result in significant errors in the estimated rotor losses, which could lead to misinformed design decisions. This Thesis makes a number of contributions to the subject of rotor losses in PM machines. It firstly investigates the accuracy of the commonly used current sheet method for estimating losses for each harmonic. In this method, the losses are calculated using a multi-layer model of the machine in which each asynchronous harmonic in the rotor frame is represented by current sheet on the surface of the bore of a slotless stator. The harmonics are calculated using double Fourier transform of flux density data on the surface of the magnet obtained from a number of magnetostatic finite element (FE) solutions at different rotor position. The losses are also calculated using 2D transient FEA with rotor motion, with appropriate mesh refinement and time step determined based on a mesh and time step dependence study. The results show that the current sheet method accurately calculates the losses in ring magnets if the amplitudes of the harmonics are estimated accurately. Secondly, the Thesis extends 3 analytical methods that have been reported in the literature by Zhu and Howe (1993), Gieras (2004) and et al (2006) to estimate the amplitude of the no-load asynchronous travelling flux density harmonics, the magnet flux tooth ripple harmonics, in the rotor frame. The accuracy of these methods is evaluated by comparison to those calculated using non-linear finite element analysis for variants of a particular machine. The results show that ( et al, 2006) complex permeance method provides the closest estimate, when the level of saturation in the machine is negligible. However, if the saturation, of the tooth tip in particular is significant, then all methods underestimate the amplitudes of the harmonics. And accordingly, the estimated rotor losses are grossly underestimated by a factor of 1:3 in a machine with heavy tooth tip saturation. Thirdly, the Thesis tackles the problem of losses in a loaded generator with sinusoidal currents. It is shown that the total losses in the machine are dependent on the power factor and the phase angle between the emf and current. The total loss cannot be simply calculated by adding the no-load loss due to magnet flux tooth ripple harmonics and the loss due to stator mmf asynchronous harmonics. This is due to the interaction between the stator mmf harmonics and the magnet flux tooth ripple harmonics, which need to be added vectorially. This is verified by comparing the results calculated analytically (using the most accurate ’s meth d f calculating no-load harmonics), with those obtained from transient FEA in a machine with no significant saturation. Fourthly, the Thesis investigates rotor losses in a generator with two slots per pole per phase connected to an uncontrolled diode rectifier, considering the two cases of constant current and constant voltage dc link. Two winding and rectifier configurations are considered: a 3-phase winding with a 3-phase, 6 pulse bridge rectifier and a double 3-phase winding with a 3-phase rectifier each, connected in series i.e., a 12 pulse rectifier. Both magnet flux tooth ripple and armature reaction stator mmf harmonics are considered in the calculation of rotor loss; the harmonics were added vectorially. It is shown that the machine with double 3-phase windings and 12 pulse rectifier has considerably lower rotor losses that the machine with one single 3-phase winding due to cancellation of high order harmonics. Finally, limited studies are performed in the Thesis for the calculation of rotor losses in PMSGs with different slot opening, number of slots per pole and airgap (with magnet thickness adjusted to keep the airgap flux density and emf constant). It is shown that increasing the airgap and reducing slot opening reduced the losses The results plotted in a normalised form of loss per unit rotor surface area are versus the ratios of gap/slot pitch and slot opening divided by pole pitch. These curves are shown to give reasonable quick estimates of rotor losses in machines with different sizes. Also, rotor losses are calculated in three PMSGs with different numbers of slots per pole and winding / rectifier configurations. The results show that the popular 1.5 slots per pole concentrated winding configuration have considerably higher rotor losses due to the strong second harmonic than the other machines with lap windings. The work in the Thesis was based on two-dimensional calculations, assuming ring magnets. Further work is needed to evaluate the 3D effect and magnet segmentation.
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Bock, Jean-Pierre. „Modélisation et calcul couplé des champs électromagnétiques dans les machines asynchrones en régime transitoire“. Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL094N.
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Ce travail apporte une contribution au calcul des machines électriques asynchrones, dans le cas ou une modélisation de type circuits couplés est impossible (rotors massifs ou à cage profonde). La première partie expose les différentes façons de prendre en compte le mouvement. La deuxième partie expose une nouvelle méthode, double entrefer et approximation du premier harmonique d'espace, qui est ensuite développée dans le cas des régimes transitoires, à courants imposés puis à tensions imposées. On montre aussi que la méthode se prête à un couplage avec des circuits électriques extérieurs. Dans la troisième partie, on procède à une validation de la méthode pour deux machines à induction pour lesquelles nous disposions de données expérimentales: une machine triphasée de 950 kW et une machine diphasée de 300 W avec condensateur. Dans la quatrième partie, on prévoit les caractéristiques d'un prototype de machine rapide (100 kW, 30 000 tr/mn) alimenté de différentes manières par deux sortes d'onduleurs. À l'approximation du premier harmonique d'espace, la méthode développée autorise des rotations élémentaires importantes, ce qui correspond à un gain de temps appréciable par rapport au suivi des grandeurs elles mêmes. La méthode peut être affinée par la prise en compte d'harmoniques supérieurs, et elle est généralisable aux cas des machines saturées
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Bonnafous, François. „Etude des pertes dans les circuits magnétiques de machine à reluctance variable alimentée à moyenne fréquence : réalisation d'un logiciel de conception de moteurs rapides“. Paris 6, 1986. http://www.theses.fr/1986PA066496.
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Conception des circuits magnétiques de machines à reluctance variable alimentées à moyenne fréquence. On y aborde le problème de l'évaluation des pertes dans le fer dans des tôles de matériau ferromagnétique soumises à des champs de forme non sinusoïdale, fonctions du temps, à l'aide de modèles théoriques et de mesures. Une étude paramétrique débouche sur la réalisation d'un logiciel de conception de moteurs rapides, prenant en compte les pertes dans les diverses parties de leur circuit magnétique.
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Král, Radek. „Vysokootáčkový synchronní stroj s vnějším rotorem“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442788.
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The master thesis deals with the construction and design of a high-speed synchronous machine with an outer rotor. The thesis is organised into three main chapters. The first chapter deals with machine design theory as well as mechanical limits, which are significant for high speed machines. This chapter also provides examples of applications of these electrical machines. In the second chapter, the initial design of the machine is calculated analytically. This machine design is optimised and the third chapter of this work shows the results of simulations using the finite elements method, including the evaluation of these results.
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Ben, Nachouane Ayoub. „Modélisation numérique des phénomènes aérothermiques dans les machines électriques en vue d’optimisation de leur conception : application aux machines électriques des véhicules hybrides et électriques“. Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2348/document.
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Implanter une machine électrique dans un véhicule hybride pose avant tout des problèmes d’encombrement. Sous-dimensionner la machine semble légitime compte tenu de l’usage qui en est fait sur véhicule. Par contre, cela suppose que les aspects thermiques soient pris en compte non seulement lors de l’utilisation, mais aussi lors de la conception de la machine. Le phénomène majeur limitant la densité de puissance massique des machines électriques est l’échauffement interne des bobines et des aimants. La modélisation thermique de la machine est complexe compte tenu de la diversité des sources de chaleur et de la coexistence de différents modes de transferts thermiques : conduction dans la matière, convection avec l’eau de refroidissement, conduction, convection et rayonnement dans l’entrefer. En termes de géométrie, si une première approche peut être réalisée en ne considérant que des flux de chaleur radiaux, la composante axiale doit nécessairement être prise en compte dès lors qu’on veut tenir compte aussi des extrémités de machine, et notamment de la chaleur produite par les roulements et les têtes de bobines. Ainsi pour pouvoir analyser pertinemment les transferts thermiques dans la machine, des méthodes numériques de type CFD ont été utilisées pour caractériser le transfert thermique par convection. La caractérisation des échanges thermiques par convection naturelle et forcée a été réalisée à l’intérieur d’une machine synchrone à aimants permanents internes (MAPI). Des relations empiriques ont été proposées afin de prendre en compte le couplage entre la thermique et l’aérodynamique dans les cavités des machines électriques totalement fermées. Afin de valider la pertinence des modèles numériques dans le cadre de ce travail, des mesures thermiques à l’aide des moyens d’essais de l’UTC ont été réalisées. Les résultats de cette étude sont utilisés pour construire des circuits thermiques équivalents qui prennent en compte les phénomènes thermiques complexes dans les machines électriques fermées utilisées dans les véhicules hybrides et électriques. Ces recommandations de conception permettront l’optimisation de l’effort investi pour le refroidissement de la machine électrique dans ses différentes phases de fonctionnementThe integration of an electrical machine into modern hybrid vehicles is associated with new technical constraints such as the integrability into small volume without losing certainly in performance. Therefore, the development of compacter electrical machines is a well-founded argument for car manufacturers as well as electrical machine designers. On the other hand, this finding assumes that the thermal aspects are undertaken not only during the operation of the electrical machine, but also during the design process. The internal heat generated in different areas impacts strongly the power density and the magnet health which deeply reduce the electrical machine reliability. Heat transfer modeling inside electrical machines is a tricky task because of the strong coupling between the different physics governing their operations. Indeed, the generated losses spread inside the electrical machine through three heat transfer modes which are: conduction (heat diffusion), convection(heat transport) and radiation (heat scattering). In terms of geometry, if a first approach can be carried out by considering only radial heat fluxes, the axially-transferred heat must be undertaken when it is also necessary to consider end caps effects, and particularly the heat released by the bearings. In order to carry out relevantly the thermal analysis of a permanent magnets synchronous machine, CFD based methods are used to characterize the convective heat transfer inside this machine over a large operating range. Both natural and forced convection are analyzed and the corresponding heat transfer coefficients are numerically-estimated. Empirical equations are proposed in order to take into account the coupling between thermal and fluid dynamics inside the cavities of the studied totally-enclosed machine. These correlations are integrated then into a detailed and reduced thermal network. Experimental tests are carried out using a test bench in order to measure temperature distribution in different areas of the electrical machine. Afterward, a comparison between estimated and measured temperatures shows that the results of the numerically-enhanced thermal network are in a good agreement with measurements. Thus, the proposed recommendations based on CFD modeling allow the convective heat transfer to be characterize quickly and precisely. These correlations are useful for upcoming studies dealing with convection inside automotive electrical machines as well as high speed electrical machines
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Bergstrom, John Paul. „High-speed high-power permanent magnet machine parameters, qualities, and considerations“. 2013. http://hdl.handle.net/2152/22747.
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Permanent magnet machines have become an attractive topology for several applications due to their high power density and brushless qualities as compared to conventional wound field machines or squirrel cage machines. The presences of permanent magnets provide distinct advantages, but at the same time unique behaviors that must be accounted for. Recent work has developed permanent magnet machines for high-power and high-speed applications such as may be found in the petro-chemical industry, naval ships, and energy storage systems.text
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„A Machine Learning based High-Speed State Estimator for Partially Observed Electric Transmission Systems“. Master's thesis, 2020. http://hdl.handle.net/2286/R.I.63057.
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abstract: The accurate monitoring of the bulk transmission system of the electric power grid by sensors, such as Remote Terminal Units (RTUs) and Phasor Measurement Units (PMUs), is essential for maintaining the reliability of the modern power system. One of the primary objectives of power system monitoring is the identification of the snapshots of the system at regular intervals by performing state estimation using the available measurements from the sensors. The process of state estimation corresponds to the estimation of the complex voltages at all buses of the system. PMU measurements play an important role in this regard, because of the time-synchronized nature of these measurements as well as the faster rates at which they are produced. However, a model-based linear state estimator created using PMU-only data requires complete observability of the system by PMUs for its continuous functioning. The conventional model-based techniques also make certain assumptions in the modeling of the physical system, such as the constant values of the line parameters. The measurement error models in the conventional state estimators are also assumed to follow a Gaussian distribution. In this research, a data mining technique using Deep Neural Networks (DNNs) is proposed for performing a high-speed, time-synchronized state estimation of the transmission system of the power system. The proposed technique uses historical data to identify the correlation between the measurements and the system states as opposed to directly using the physical model of the system. Therefore, the highlight of the proposed technique is its ability to provide an accurate, fast, time-synchronized estimate of the system states even in the absence of complete system observability by PMUs.
The state estimator is formulated for the IEEE 118-bus system and its reliable performance is demonstrated in the presence of redundant observability, complete observability, and incomplete observability. The robustness of the state estimator is also demonstrated by performing the estimation in presence of Non-Gaussian measurement errors and varying line parameters. The consistency of the DNN state estimator is demonstrated by performing state estimation for an entire day.Dissertation/Thesis
Masters Thesis Electrical Engineering 2020