Sökning: "variable frequency"

Visar resultat 1 - 5 av 236 avhandlingar innehållade orden variable frequency.

  1. 1. The Frequency of the Frequency : On Hydropower and Grid Frequency Control

    Författare :Linn Saarinen; Urban Lundin; Per Norrlund; Bengt Carlsson; Kjetil Uhlen; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydropower; frequency control; governors; power system stability; inertia; primary control; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : Variations in the electricity consumption and production connected to the power system have to be balanced by active control. Hydropower is the most important balancing resource in the Nordic system, and will become even more important as the share of variable renewable energy sources increases. LÄS MER

  3. 2. Modelling of cavity partial discharges at variable applied frequency

    Författare :Cecilia Forssén; Roland Eriksson; Hans Edin; Peter H.F. Morshuis; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; partial discharges; measurements; modelling; variable frequency; cavities; disc-shaped; polycarbonate; Electric power engineering; Elkraftteknik;

    Sammanfattning : The presence of partial discharges (PD) in high voltage components is generally a sign of defects and degradation in the electrical insulation. To diagnose the condition of high voltage insulation, PD measurements is commonly used. LÄS MER

  4. 3. Partial Discharges Studied with Variable Frequency of the Applied Voltage

    Författare :Hans Edin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; diagnostic methods; partial discharges; phase resolved; variable frequency; dielectric spectroscopy; dielectric response; harmonics; insulation; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

    Sammanfattning : This thesis concerns partial discharge (PD) diagnostics withvariable frequency of applied voltage in the frequency range 1mHz - 400 Hz. The exploration of a new type of spectroscopythat combines partial discharge analysis and dielectricresponse is demonstrated. LÄS MER

  5. 4. Synchronous generator and frequency converter in wind turbine applications : system design and efficiency

    Författare :Anders Grauers; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; synchronous generator; frequency converter; wind turbine; avrage efficiency; losses; system design; variable speed;

    Sammanfattning : This report deals with an electrical system for variable-speed wind powerplants. It consists of a synchronous generator, a diode rectifier and athyristor inverter. LÄS MER

  7. 5. Frequency Response by Wind Farms in Islanded Power Systems with High Wind Power Penetration

    Författare :Mattias Persson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Synthetic inertia; rate of change of frequency; inertia emulation; variable speed wind turbine; frequency control;

    Sammanfattning : The integration of variable speed wind turbines (VSWT) in power systems keep increasing inorder to reduce the emission of green house gases. This increase of power electronic converterinterfaced generation causes a decrease of power system inertia and issues previously existingin power systems tend to become more complicated and new solutions should be evaluated. LÄS MER