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WG C4.409 Lightning Protection of Wind Turbine Blades

 
Background:

In recent years, Lightning damages to wind –power plants are increasing as the number and size of wind turbines becoming rapidly larger. Especially lightning damages to wind turbine blades are quite serious since the cost for replacements is remarkably high and long repair time is necessary. Outages of wind –power plants have been investigated in the world and the statistical results are shown inDenmark,Germany,Spainand Japan etc. There are many experimental researches related to the attachment manner of lightning strokes to blades using high voltage generators. On the other hand, observations on the lightning attachment manner to blades and the lightning currents have been carried out mainly inJapan.

IEC TC88 PT 24 published TR 610400-24 on thelightningprotectionof wind turbine generator systems. Lightningparameters referred to in this document are those forsummerlightning, however, the parameters of winterlightningalong thecoastof theSea of Japanneed further investigation. Damages of blades of wind turbines, frequently experienced in the above area in winter, are related to theenergyoflightningcurrents having long duration. If a lightning strokeattaches to aninsulatedbladeand the electricdischargepenetratesintoit, breakage of the blade may occur due to the excessive pressure generated in its cavity by the electric arc of long duration. Statistics of the energy of lightning flashes in winter have not been established regardless of the polarity of currents.

In spite of these recent research activities, lightning protection methods of wind turbine blades have not been fully established, because observation of the phenomena is not sufficient and the experimental method has not been reached to agreement for various types of blades.

In order to establish better protection measures for wind turbine blades, it is important to evaluate existing lightning observation systems and to analyse the observation results collected so far to decide the appropriate testing methods for lightning protection of blades.

Scope:

Thescopeof theworkinggroupis to:

  • Summarizethemeasureddatarelatedto theattachmentmanneroflightningstrokes tobladesofwindturbines.
  • Summarizethemeasureddataoflightningcurrents inwindturbines. InJapanlightningcurrentswithchargesover300coulombs are notunusualinwinterseasons on thecoastalareaalongtheSea ofJapan.
  • Investigate laboratory and field test methods based on observation results and experimental researches related to the attachment manner of lightning to wind turbine blades.
  • Evaluate the quality of current data observed by newly developed Rogowsky-coils for measuring lightning currents of long duration.
Deliverable:

Thesummarymay bepublished in theElectra.

Convener: S. Yokoyama (Japan)

Progress Report 2013 (pdf, 134kB)