Design of a superconducting DC wind generator

The trend towards larger power ratings of wind turbines asks for innovations in power generation, which requires lower weight and cost, smaller size, higher efficiency and reliability. Due to high current-carrying capability and no DC losses of superconductors, a superconducting wind generator can have a superior power to weight/volume ratio with high efficiency. The work in the book mainly focuses on the feasibility study and design of a superconducting DC wind generator

Position estimation and performance prediction for permanent-magnet motor drives

PhD ThesisThis thesis presents a theoretical and experimental development of a novel position estimator, a simulation model, and an analytical solution for brushless PM motor drive. The operation of the drive, the position estimation model of the test motor, development of hardware, and basic operation of inverter are discussed. Starting with the well-known continuous-time model of brushless PM motor, a sampled-data model is developed that is suitable for th6, application of real-time position estimator. An analytical methodo f calculating the steady-stateb ehaviouro f the brushlessP M motor for 1200in verter operation is presentedT. he analysisa ssumesth at the machinea ir gap is free of saliency effects, and has sinusoidal back EMF. The analytical solution is derived for 60" electrical of the whole period. By experimental results, it is shown that the method of analysis is adequate to predict Ihe motor's performance for typical operating points including phase advance and phase delay operation. C) I A computer simulation model for prediction of the performance of brushless PM moto rs is presented. The model is formulated entirely in the natural abc frame of reference, which allows direct comparison of the simulation and corresponding experimental results. The equations and diagrams are put into a convenient form for the simulation and future developments and library modules. The simulation model and corresponding experimental data of the brushless PM motor drive is given. The thesis describes a modem solution to real-time rotor position estimation, which has been subject to intense research activity for the last 15 years. The implemented new algorithm for shaft position sensorless operation of PM motors is based on the flux linkage and line current estimation. The position estimation algorithm has also been verified by both off-line and on-line experiments (accomplished by a DSP, TMS320C30), and a wide range of steady-statea nd transient results have been 0gi0v en including starting from rest. The position estimation method effectively moves the position measurement point in the drive from the mechanical side to the motor's terminals. As well as eliminating the mechanical shaft position sensor, the investigated method can be used for high performance torque control of brushless PM motors. The thesis demonstrates that, in contrast to many other "sensorless" schemes, the new position estimation method is able to work effectively over the full operating range of the drive, and is applicable to a wide range of motor/converter types. Since the hardware is straightforward, only the new position estimation algorithm differentiates a system. Therefore, if a DSP control system is already implemented in the drive, the position estimator can be implemented at low cost.Istanbul Technical University and Higher Education Counci

Design of a superconducting DC wind generator

Offshore wind energy has received a lot of interest as one important renewable energy source. One promising way to reduce the Levelized Cost of Electricity (LCOE) of offshore wind energy is by developing large wind farms and turbines with large ratings. The average wind turbine size has reached 4.2 MW in 2015 and turbine sizes of 6-8 MW have already been seen in the wind market. Even larger turbine sizes are managing to pave their way from studies to market. The trend towards larger ratings and more offshore installations asks for innovations in power generation, which requires lower weight and cost, smaller size, higher efficiency and reliability. Due to the high current-carrying capability and no DC losses of the superconductors, superior power to weight/volume ratio with high efficiency of a superconducting generator can be achived. Moreover, direct current (DC) transmission has been put forward for the offshore wind farms mainly due to the overall economic benefit, as they are located far away from the land. Hence, this thesis introduces a DC generation and transmission scheme which consists of superconducting DC wind generators and superconducting DC cables as a possible technical solution. This enables a highly efficient and compact generator and in addition a new and also very efficient generator connection scheme at DC. The work presented in the thesis focuses on the feasibility study and design of a superconducting DC wind generator. In part, an optimisation method will be developed by taking superconducting tape length (cost), mass, volume, and efficiency into a simplified objective function. All necessary analytical equations will be derived to connect the electromagnetic design and mechanical design with properties of the superconducting tapes and iron materials. To increase the design accuracy, analytical equations to calculate flux density distribution in the superconducting DC generator will be verified by finite element analysis. Not only the active parts but also inactive structural materials will be included in the mass calculation. Based on the design method, the design of a 10 kW superconducting DC generator demonstrator will be described. The losses of the demonstrator and its commutation, torque and efficiency at different wind speeds will be addressed. As first steps towards the demonstrator, properties of key components, superconducting tapes, iron materials and a superconducting coil, will be tested and characterized. Moreover, a preliminary test of a superconducting coil at 77 K will be completed. In order to identify the potientials that a large scale superconducting DC wind generator could offer, a 10 MW superconducting DC generator will be designed and a comparison with conventional synchronous generators will be made. Additionally, this work will also discuss the savings of HTS tapes by optimizing outer rotor diameter, pole pair number, and superconducting coil height, which contribute to a more competitive alternative to conventional generators

Mathematical Models for the Design of Electrical Machines

This book is a comprehensive set of articles reflecting the latest advances and developments in mathematical modeling and the design of electrical machines for different applications. The main models discussed are based on the: i) Maxwell–Fourier method (i.e., the formal resolution of Maxwell’s equations by using the separation of variables method and the Fourier’s series in 2-D or 3-D with a quasi-Cartesian or polar coordinate system); ii) electrical, thermal and magnetic equivalent circuit; iii) hybrid model. In these different papers, the numerical method and the experimental tests have been used as comparisons or validations

Electronic/electric technology benefits study

The benefits and payoffs of advanced electronic/electric technologies were investigated for three types of aircraft. The technologies, evaluated in each of the three airplanes, included advanced flight controls, advanced secondary power, advanced avionic complements, new cockpit displays, and advanced air traffic control techniques. For the advanced flight controls, the near term considered relaxed static stability (RSS) with mechanical backup. The far term considered an advanced fly by wire system for a longitudinally unstable airplane. In the case of the secondary power systems, trades were made in two steps: in the near term, engine bleed was eliminated; in the far term bleed air, air plus hydraulics were eliminated. Using three commercial aircraft, in the 150, 350, and 700 passenger range, the technology value and pay-offs were quantified, with emphasis on the fiscal benefits. Weight reductions deriving from fuel saving and other system improvements were identified and the weight savings were cycled for their impact on TOGW (takeoff gross weight) and upon the performance of the airframes/engines. Maintenance, reliability, and logistic support were the other criteria

Fault analysis and protection for wind power generation systems

Wind power is growing rapidly around the world as a means of dealing with the world energy shortage and associated environmental problems. Ambitious plans concerning renewable energy applications around European countries require a reliable yet economic system to generate, collect and transmit electrical power from renewable resources. In populous Europe, collective offshore large-scale wind farms are efficient and have the potential to reach this sustainable goal. This means that an even more reliable collection and transmission system is sought. However, this relatively new area of offshore wind power generation lacks systematic fault transient analysis and operational experience to enhance further development. At the same time, appropriate fault protection schemes are required. This thesis focuses on the analysis of fault conditions and investigates effective fault ride-through and protection schemes in the electrical systems of wind farms, for both small-scale land and large-scale offshore systems. Two variable-speed generation systems are considered: doubly-fed induction generators (DFIGs) and permanent magnet synchronous generators (PMSGs) because of their popularity nowadays for wind turbines scaling to several-MW systems. The main content of the thesis is as follows. The protection issues of DFIGs are discussed, with a novel protection scheme proposed. Then the analysis of protection scheme options for the fully rated converter, direct-driven PMSGs are examined and performed with simulation comparisons. Further, the protection schemes for wind farm collection and transmission systems are studied in terms of voltage level, collection level wind farm collection grids and high-voltage transmission systems for multi-terminal DC connected transmission systems, the so-called “Supergrid”. Throughout the thesis, theoretical analyses of fault transient performances are detailed with PSCAD/EMTDC simulation results for verification. Finally, the economic aspect for possible redundant design of wind farm electrical systems is investigated based on operational and economic statistics from an example wind farm project

Performance Evaluation and Life Cycle Cost Analysis of the Electrical Generation Unit of a Wave Energy Converter

The main focus of this work is the performance and the economical assessment of a radialflux generator that is used in wave power applications. The wave energy converter (WEC) usedin this work is a point absorber, that is considered to move only in heave. The generation unitof the WEC consists of a permanent magnet machine and a power electronic converter.The straight and v-shaped interior mounted permanent magnet generators, surface mountedpermanent magnet generator and neodymium and ferrite assisted synchronous reluctance generatorsare selected as the main generator designs to be studied in this work. These designs areanalysed using finite element method (FEM) and the annual energy productions and losses arequantified. Furthermore, some design variations such as, different iron materials, stator slot geometriesand a SiC MOSFET based converter are investigated, in order to assess the impact ofa specific design variation on the energy efficiency. An economical evaluation of these variantsusing the life cycle cost (LCC) analysis is performed, in order to quantify the economical consequencesof the energy losses during the operational life time, as well as determining the costsof the initial generator investment. The results obtained suggest favorableWEC generator typesand design alterations for LCC improvements.An important finding is that the PM assisted SRM generator provides the best energy performance,given the same geometry and material limitations. The annual energy productionachieved by the SMPM generator is fairly similar to that of the IPM generator, despite not beingable to provide the required torque at high speed operations, since the high speed operationsoccur rarely. Moreover, it is found that the poor field weakening trajectory of the SMPM can beimproved by placing iron pieces at magnet sides. Another interesting result is that even thoughthe annual energy production is increased when the rotor material is replaced by a cobalt-iron,due to its high costs, this design was not found economically favorable. The design variationthat improves the electric generation system of theWEC to the highest degree is found to be theSiC MOSFET based converter design, rather than the IGBT variant. The annual energy lossesdecrease by 5 MWh, due to up to 3 times lower converter losses. Owing to the substantialenergy improvement, the SiC MOSFET case is the economically favorable choice compared tothe generation system that uses an IGBT converter, despite theMOSFET modules being 7 timesmore costly than its IGBT counterpart

Feasibility Study of Ferromagnetic Particulate Path Diversion in Additive Manufacturing

The use of electromagnetic actuator components typically involves a coil comprised of a stack-packed continuous winding, usually layered, and a core material of soft iron or at least a solenoid, similarly constructed, simply with an air core. These are used widely across, but not limited to, several industries such as automotive, aerospace, medical, and various electronics. Their application to additive manufacturing (AM), and in particular to improvement of catchment efficiency, is a somewhat newly ventured avenue and the use of permanent magnets in their place to simulate their presence is of similar vein. The objective of this thesis is to introduce a novel but constructive approach to implement catchment efficiency improvement with regard to ferromagnetic particles by increasing their density in proximity to the melt pool through introduction of a magnetic (or electromagnetic) field. This field acts to produce a lensing or concentric constriction of the particle stream above, and as its contents near and enter the AM build zone. The particle dynamics and stream studied have a purely vertical initial velocity and steady flow rate. Not discussed are melt pool effects from the introduced magnetic field, or angled AM particle streams. Four analytical methods to determine the magnetic (B) field either on or off the axis of a solenoid are first studied, then narrowed to two to verify Matlab programming from an established benchmark. A finite element (FEA) model is constructed to provide simulations and a soft iron particle is introduced to further determine validity of Matlab programming for both air core and iron core constructs. A similar process uses permanent magnets in place of a coil. A parametric sweep in the FEA software generates force data for post-processing in Matlab to produce particle displacement plots using differential equations to complete this technique. The aforementioned simulation process serves as confirmation of particle path diversion and additional experimental validation is proposed. The experiments would substantiate particulate path diversions in the presence of the permanent magnet configuration, substituted for a coil configuration, to confirm the simulated construct to be authentic regarding its required particulate force effects

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 37)

Abstracts are provided for 76 patents and patent applications entered into the NASA scientific and technical information systems during the period January 1990 through June 1990. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application