Sökning: "synchronous generators"

Visar resultat 21 - 25 av 48 avhandlingar innehållade orden synchronous generators.

1. 21. Voltage Transients in the Field Winding of Salient Pole Wound Synchronous Machines : Implications from fast switching power electronics

   Författare :Roberto Felicetti; Urban Lundin; Jon Kjellin; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency;

   Sammanfattning : Wound Field Synchronous Generators provide more than 95% of the electricity need worldwide. Their primacy in electricity production is due to ease of voltage regulation, performed by simply adjusting the direct current intensity in their rotor winding. LÄS MER

3. 22. Analysis, Modeling and Control of Doubly-Fed Induction Generators for Wind Turbines

   Författare :Andreas Petersson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : This thesis deals with the analysis, modeling, and control of the doubly-fed induction machine used as a wind turbine generator. The energy efficiency of wind turbine systems equipped with doubly-fed induction generators are compared to other wind turbine generator systems. LÄS MER

4. 23. Contributions to the electromechanics of unbalanced magnetic pull in a synchronous hydropower generator

   Författare :Yogeshwarsing Calleecharan; Timo Holopainen; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hållfasthetslära; Solid Mechanics;

   Sammanfattning : Misalignment between the rotor geometrical axis and the geometrical stator axis in a hydropower generator is usually present at standstill and when the machine is under operation. Now, rotor-stator eccentricity in a rotating electrical machine is a harbinger to abnormal operating conditions of the machine. LÄS MER

5. 24. Core Loss Prediction in Hydroelectric Generators and Analysis of a Contra-Rotating Machine Topology

   Författare :Martin Ranlöf; Uppsala universitet; []
   Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : The call for increased accuracy in the process of design and analysis of electrical machines has encouraged the use of numerical methods to calculate the electric and magnetic field distributions within this type of apparatus. The finite element method is a numerical technique that has become specifically widespread and popular, due to the relative swiftness and accuracy with which it is possible to treat complex machine geometries and non-linear material characteristics. LÄS MER

7. 25. A New Paradigm for Large Brushless Hydrogenerators : Advantages Beyond the Static System

   Författare :Jonas Kristiansen Nøland; Urban Lundin; Phil Mellor; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Brushless exciters; Rotating exciters; Permanent Magnet Machines; Synchronous Generator Excitation; Thyristor Rectifiers; Chopper Rectifiers; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : The grid code, FIKS, from the Norwegian transmission system operator (TSO), Statnett, states that synchronous generators > 25MVA, must have a static excitation system. However, an improved brushless excitation system is in operation on some commercial power plants (36MVA, 93.75rpm & 52MVA, 166. LÄS MER