Sökning: "rate of change of frequency"

Visar resultat 1 - 5 av 116 avhandlingar innehållade orden rate of change of frequency.

  1. 1. Integration of Non-synchronous Generation - Frequency Dynamics

    Författare :Johan Björnstedt; Industriell elektroteknik och automation; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Frequency control; Frequency dynamics; Frequency response; Non-synchronous generation; Power system; Synthetic inertia; Wind power;

    Sammanfattning : Traditionally the predominant generation has been large synchronous generators providing the system inertia. Nowadays when wind power and other non-synchronously connected units displaces this synchronous generation, the system inertia is reduced. Hence higher rate of change of frequency and larger frequency deviations are expected. LÄS MER

  3. 2. The Physiology of Chicken Domestication : Involvement of the HPA-axis and the Autonomic Nervous System

    Författare :Magnus Elfwing; Jordi Altimiras; Michael Axelsson; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Domestication; chickens; HPA-axis; autonomic nervous system; heart rate; allometry;

    Sammanfattning : Domesticering är en urvalsprocess för önskvärda egenskaper hos djur som över tid förändrar deras utseende, beteende och genetik. Några exempel av djur som genomgått denna riktade avel är vargen, mufflon, uroxen, vildsvinet och den röda djungelhönan som vi idag känner som hunden, fåret, kon, grisen och slaktkycklingen. LÄS MER

  4. 3. 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

  5. 4. Pollinators, Enemies, Drought, and the Evolution of Reproductive Traits in Primula farinosa

    Författare :Per Toräng; Jon Ågren; Johan Ehrlén; Rebecca Irwin; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ecology; Alternative reproductive strategies; climate change; facilitation; floral display; flowering phenology; frequency-dependent selection; genetic diversity; life-history strategies; local adaptation; pollination; predation; Primula farinosa; reproductive effort; soil disturbance; stochastic growth rate; Ekologi;

    Sammanfattning : In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits and population differentiation in the insect-pollinated, self-incompatible, perennial herb Primula farinosa. More specifically, I (1) determined whether the effects of floral display and interactions with pollinators and seed predators, and plant reproductive success were frequency-dependent and affected by surrounding vegetation context, (2) examined the consequences of intermittent drought years on population dynamics using numerical simulations based on demographic data collected over seven years, (3) analyzed among-population differentiation in flowering phenology and reproductive allocation, and its relationship to soil-depth at the site of origin. LÄS MER

  7. 5. 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