Wind turbines are isolated towers that are very tall and which utilize sensitive electronic equipment for their functionality. Just by their very nature they are at a constant threat from lightning damage. In order to mitigate the risks to the structure, the best line of defense is a properly installed and functioning lightning protection system which has the capacity to intercept the lightning and subsequent surge, and safely conduct it to the earth. As wind turbine systems become more and more sophisticated, their vulnerability to lightning strikes is compounded. The systems which protect these structures from lightning generally will cost less than 1% of the total operational cost of the turbine, while improving both the reliability and cost effectiveness.
Facts about lightning danger to wind turbines
- It is noted that during the first year of operation of a newly installed wind turbine, 85% of down-time is lightning-related on a southwestern wind farm. Often totals for lightning-related damage and repair will exceed $250,000.
- A study in Germany of wind farms revealed that lightning strikes resulted in 80% of all insurance claims involving wind turbines.
- Energieerzeugungswerke Helgoland GmbH is a German electric power company that shut down the operations of, and completely dismantled the Helgoland Island wind power plant, when they were denied insurance coverage against “lightning related” losses. In three years of operation they had experienced more than $540,000 in damage as a result of lightning.
- Lightning strike dangers increase with turbine height.
Facts about damage to wind turbine components
- These are the systems that can be damaged by lightning strikes to wind turbines, ordered from most to least vulnerable.
- Control Systems: The sensitive equipment that controls the actual system of the wind turbine includes the sensors, motors and actuators that are responsible for actually steering the turbine equipment into the wind itself. Damage to the control system: The National Fire Protection Association handbook states that “While physical blade damage is the most expensive and disruptive damage caused by lightning, by far the most common is damage to the control system.”
- Electronics: Wind turbines are far more complex than they appear on the surface. They will house a transformer station, frequency converter, switchgear elements, as well as other expensive equipment. All of this is housed within an incredibly small space, and all is joined together through power lines which conduct surge electricity.
- Blades: When a turbine blade is struck (if unprotected) its temperature will raise immediately to as high as 54,000 F, and the resulting expansion of air within the blade is explosive. This temperature will damage the surface of the blade, melt the glue and crack the leading and trailing edges. Undetected damage will significantly shorten the lifespan of the blades. A study has recently found that wood epoxy blades are more lightning-resistant than GRP/glass epoxy blades.
- Generators and Batteries: Both of these components will be damaged and potentially exploded by a lack of protection during a lightning strike.
Lightning codes, with regard to the danger lightning poses to wind turbines, “provide more benefit to commercial vendors than to those seeking relief from lightning’s effects” and that “devices that claim to offer absolute protection abound in the marketplace, confusing specifying architects, engineers, and facility managers,” according to the National Lightning Safety Institute.
Solar Age Magazine recently published an article that offers the following recommendations for lightning protection of wind turbines:
- Each wire entering the electrical panel box should be protected with a surge suppressor grounded to an existing ground rod. There should be only one ground rod in the installation, which should make “better contact with the moisture in the ground than do the tower footings.”
- Lightning rods will not effectively protect the wind turbines electronic equipment, and will obstruct the flow of wind around the turbine blades, thus reducing the efficiency of the system.
Raycap’s Strikesorb line of SPDs will provide the highest level of lightning protection for wind turbines available to the commercial or residential markets, allowing for effective industrial-levels of wind turbine surge protection while also offering the longest uptimes available to systems. This is achieved through the proprietary technology that Raycap systems offer, which require no resetting or maintenance over their life spans. Contact Raycap representatives today for more information about these exciting products.