Lightning protection of wind turbines

    Research output: ThesisDoctoral Thesis

    Abstract

    Wind turbines are the largest contributor to renewa
    ble energy both in Britain and the
    rest of Europe. With a rise in the installed capaci
    ty and an increase in offshore wind
    energy due to governments green targets by 2020, th
    ere has been a large
    development in new wind turbines for optimized perf
    ormance. The present thesis deals
    with the uncertainties in regards to the lightning
    phenomenon on wind turbines with
    emphasis on the rotor blades. Rotor blades are the
    most expensive part to replace in
    the event of lightning related damage. The research
    presents results based on lightning
    data analysis on wind turbines, backed up by finite
    element analysis testing of wind
    turbine systems. The final chapters include the tes
    ting and improving of lightning
    protection systems installed on modern day rotor bl
    ades.
    The first part of the thesis deals with the theoret
    ical understanding of the lightning
    phenomenon and its effect on wind turbine systems.
    The core work of the research
    begins with the analysis of lightning data collecte
    d over Nysted wind farm and different
    wind turbines installed over the world. The data an
    alysis helps in identifying the parts of
    the wind turbine that are at high risk to lightning
    attachment and related damage. The
    peak current levels of the lightning strikes seen o
    n the wind turbine are compared with
    those in modern day lightning standards, and show t
    hat historic data in the standards
    are not an exact match to the real case scenarios.
    The lightning data analysis also
    sheds light into the importance of upward initiated
    lightning, which will become
    important for large wind turbines, especially in th
    eir new offshore environment. A full
    scale 3D FEA model of a wind turbine, with lightnin
    g protection systems installed in its
    rotor blades, is subjected to electrical stresses t
    o find likely attachment points in
    regards to upward initiated lightning, and these re
    sults are later compared to those
    found in the data analysis.
    The second half of the thesis deals with the testin
    g of new materials and prototype
    blades, to be introduced to reduce their radar cros
    s section. The new materials include
    a large amount of carbon content which affects the
    efficiency of the lightning protection
    system. High voltage and high current tests backed
    up with finite element analysis
    have been performed to find how these new materials
    affect the performance of the
    lightning protection system. The results indicate t
    hat further work needs to be done
    before these new materials can be integrated into t
    he blade, as they increase the risk
    of lightning related damage to the blade.
    Original languageEnglish
    Supervisors/Advisors
    • Cotton, Ian, Supervisor
    Publisher
    Publication statusPublished - 2010

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