43 research outputs found

    High-Temperature Superconducting Wind Turbine Generators

    Get PDF

    Superconducting Wind Turbine Generators

    Get PDF

    Comparison of Electromagnetic Performance of 10-MW Superconducting Generators With Different Topologies for Offshore Direct-Drive Wind Turbines

    Get PDF
    This paper compares the electromagnetic performance of 10MW superconducting (SC) generators with three different topologies, i.e., iron-cored stator and rotor (ISIRT), iron-cored stator and air-cored rotor (ISART), and air-cored stator and rotor (ASART). The objective is to provide a powerful insight into the advantages and disadvantages of the different topologies, and to establish some design guidelines for selecting an appropriate direct drive SC generator for offshore wind turbine applications. Firstly, the structures of the three SC generator topologies are introduced. Then, the influence of the SC coil cross sectional area on torque capability is compared. After that, three SC generators with different topologies are optimized respectively for further comparison, including the active material cost, weight, harmonics in the electromotive force (EMF), torque ripple, field harmonics in the SC coil, and forces on the rotor and stator components, etc. It is found that, with the same SC quantity, the torque capability of the iron-cored stator and rotor topology is much better than that of the other two topologies. However, the advantage becomes less significant when a larger area of the SC coil is employed. The air gap flux density waveform of the ASART is much smoother than those of the ISIRT and ISART. The torque ripples of the ISIRT and the ISART are much higher than that of the ASART. The field harmonics (both amplitude and frequency) in the SC coil of the ASART are the lowest. For the ISIRT, most of the force on the rotor is acting on the rotor iron, and thus, the SC coil is more likely to be safe from a mechanical performance point of view and the design of the corresponding supporting structure is simple. However, for the air-cored rotor topologies, nearly all the force is acting on the SC coil. For the air-cored stator, the force mainly acts on the armature winding, while for the iron-cored stator, it is mainly on the stator teeth. Due to the excellent mechanical performance of iron, the iron-cored stator is therefore more robust

    Design of a superconducting DC wind generator

    Get PDF
    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

    Design of a superconducting DC wind generator

    Get PDF
    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

    Development and test of a technology wind generator demonstrator with no insulation field coils applying high temperature superconductors

    Get PDF
    Der steigende Bedarf an günstigen, erneuerbaren Energiequellen verursacht eine anhaltende Entwicklung hin zu Windkraftanlagen höherer Leistungsklassen. Generatoren dieser Leistungsklassen sind meist besonders schwer und weisen erhöhte Anforderungen bezüglich des Bauraums auf. Supraleitende Materialien mit ihrer hohen Stromtragfähigkeit und nicht vorhandenen Gleichstromverlusten, zeigen das Potential einer erhöhten Leistungsdichte von elektrischen Maschinen hinsichtlich Gewicht und Volumen. Diese Arbeit stellt deshalb die Entwicklung und den Test eines Generator-Technologiedemonstrators mit Felderregerspulen, bestehend aus Hochtemperatur-Supraleitern, vor. Für eine verbesserte elektrische und thermische Stabilität sind die supraleitenden Spulen als nicht-isolierte Spulen ausgeführt und verfügen deshalb über keine elektrische Isolation zwischen den Spulenwindungen. Die grundsätzlichen Ausführungsformen supraleitender elektrischer Maschinen im Hinblick auf den Einsatz in Windkraftanlagen werden vorgestellt. Dabei werden insbesondere die Ausführung ferromagnetischer Komponenten, die Verwendung der supraleitenden Materialien im stationären und rotierenden Teil der Maschine als auch das kryogene Kühlsystem behandelt. Auf Grundlage dieser Vorüberlegungen wird das Design eines partiell supraleitenden Synchrongenerators mit stationären, supraleitenden Felderregerspulen und einer normalleitenden, rotierenden Drehstromwicklung gewählt. Das Statoreisen ist dabei als vom kryogenen System entkoppeltes warmes Eisen realisiert und sowohl Statoreisen als auch Rotoreisen sind als Luftspaltwicklungen ausgeführt und weisen keine ausgeprägten ferromagnetischen Nuten auf. Die Kühlung der supraleitenden Spulen und Subkomponenten erfolgt mittels eines direkten, leitungsgekühlten kryogenen Kühlsystems im Stator der Maschine. Basierend auf der gewählten Ausführungsform der elektrischen Maschine wird ein detailliertes elektromagnetisches, thermisches und mechanisches Design eines Generator-Technologiedemonstrators erarbeitet. Hierbei wird nicht nur die Wechselwirkung der genannten physikalischen Domänen untereinander, sondern auch die grundsätzliche praktische Umsetzbarkeit berücksichtigt. Im Rahmen dieser Arbeit kommen Hochtemperatur-Supraleiter von zwei verschiedenen Herstellern zum Einsatz, die beide hinsichtlich der Verwendung in den supraleitenden Spulen des Generators vorcharakterisiert werden. Insgesamt werden 14 supraleitende Generatorspulen hergestellt und erfolgreich bezüglich ihrer supraleitenden Eigenschaften und dem aufgrund der fehlenden Windungsisolation besonderen dynamischen Verhaltens in Flüssigstickstoff bei 77 K getestet. Zusätzlich wird in einem speziellen labortechnischen Aufbau die leitungsgekühlte Anbindung von zwei Spulen für Temperaturen unterhalb von 77 K untersucht. Zwölf Felderregerspulen werden zu einem sechspoligen Spulensystem mit sich ausbildenden, alternierenden magnetischen Polen zusammengefügt. Das Spulensystem, die Komponenten des kryogenen Kühlsystems, das Statoreisen sowie die mechanischen Stützstrukturen werden im Vakuumraum des Kryostaten installiert. In der kryogenen Umgebung im Stator des Generator Technologiedemonstrators wird das Spulensystem auf die angestrebte Betriebstemperatur von 30 K gekühlt und erfolgreich mit einem Nennstrom von 450 A betrieben

    Advancement of direct drive generator systems for offshore renewable energy production

    Get PDF
    As machine topologies and technologies mature, the fundamental function of the device is honed. Direct drive machines have the potential to launch the renewable energy sector into a new era of large scale, reliable, offshore power generation. With advancements in new technologies, such as superconductivity, the reduction of generator mass due to incorporation of machine and device structures, the continued advancements in component and system reliability; direct drive generators have the ability to outsize geared wind systems and simplify submerged linear and rotary power generation. The research held within this thesis will focus on improving direct drive power take off systems for offshore renewable energy power generation by splitting the area into four parts. The first part will discuss the various methods of energy extraction within the offshore and marine environment. The future of the sector will be discussed, and a forecast of technological advancement and existing reliability issues will be provided based on current data. The second part will focus on drive trains and direct drive generators, assessing the current topologies and suggesting alternatives that may thrive in a variety of large and small offshore renewable machines. The third part investigates the application of novel linear bearings in direct drive systems for offshore and submerged operation. A brief study of the loads found in wave applications will be presented and the testing of several polymer bearing materials will be outlined. The final part will discuss the potential benefits of flooding the airgap of a direct drive generator with sea water for marine applications. Results will be presented from two linear test rigs and the marinisation of devices will conclude the report
    corecore