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Lightning protection of wind turbine blade by high electric charge coating

IP.com Disclosure Number: IPCOM000191222D
Publication Date: 2009-Dec-21
Document File: 5 page(s) / 41K

Publishing Venue

The IP.com Prior Art Database

Abstract

A novel coating of highly conducting particles is proposed that will dissipate a charge to the receptors at very fast rate without damaging the blade or blade surface due to excessive heating and corona formation. It is proposed to deposit the coating using an appropriate method, such as but not limited to, a low velocity spray process (LVSP). This process is expected to produce the adhering coating and protect the turbine blade from damage due to lightning strikes. The conducting particles are expected to conduct the lightning from the blade surfaces to the lightning receptors, without burning the glass fibers or carbon fibers of the blades.

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Lightning protection of wind turbine blade by high electric charge coating

Abstract

Dielectric coatings are typically applied to the surface of the turbine blades to improve the insulation performance. Such coatings reduce the degree of surface roughness on blade surface, thus decreasing the high local electric fields and help to protect the blade from high voltage failures. To avoid damage or destruction by lightning strikes, these blades are equipped with a lightning protection system (LPS).  The most common LPS consists of several metallic receptors that are provided on the blade shell and are internally connected to ground by a conductor. The receptors are usually grounded using graphite-coated copper strips.  The receptors offer protection at defined impact positions for the lightning strike. For shorter blades, this concept has proved to be sufficient, but for longer blades (up to 50 meters length), the receptor concept may not provide adequate protection at all locations of the blade. 

A novel coating of highly conducting particles is proposed that will dissipate a charge to the receptors at very fast rate without damaging the blade or blade surface due to excessive heating and corona formation.  It is proposed to deposit the coating using an appropriate method, such as but not limited to, a low velocity spray process (LVSP). This process is expected to produce the adhering coating and protect the turbine blade from damage due to lightning strikes.  The conducting particles are expected to conduct the lightning from the blade surfaces to the lightning receptors, without burning the glass fibers or carbon fibers of the blades.

Background

1. 2007_08_01_Report_CDC_GRC: Conductively Doped Coating; authors, Bastian Lewke & Yarú Méndez Hernández

 
Wind turbine blades may loose structural integrity following a lightning strikes and this may be a common cause of their failure.  Combustible material used in the manufacturing process is also often ignited, while the turbine continues to turn, fanning the flames as it does so until the blade can disintegrate.  As a consequence, large pieces of burning material can be thrown to a considerable distance.  Fiberglass and carbon blades in service suffer lightning strikes at a disturbing rate, and that such strikes can be catastrophic, causing blade destruction.  An arc can be generated on the inside of the blade, and the shock/explosive overpressures associated with the high-energy component of the lightning strike result in the damage.  The lightning arc can be found to puncture through the center of the blade by formation of an arc, channel through drain holes at or near blades tips, or through cavities, flaws, and bond lines.  It is likely that the presence of moisture and dirt in the blades or in cavities can assist the formation of a current path.  The explosive vaporization of moisture can contribute to the pressure increase an...