POWER May 2015 - 18

Innovative Wind Turbine
Blade Inspection and
Maintenance Tools
The life of a wind turbine can be pretty
precarious. The blades-made of laminated
materials, such as composites,
balsa wood, carbon fiber, and fiberglass-can
reach speeds up to 180 miles
per hour at the tip, which means even
small particles in the air can cause damage
to the surfaces. It's probably no surprise
that lightning is a serious hazard
for wind turbines too.
Damaged blades are susceptible to
moisture intrusion, which can quickly
result in more harm as a consequence of
freeze/thaw cycling. Leading edge erosion
and deteriorating gel coats can also significantly
decrease the lifespan of a blade
and cause performance losses.
Visual inspections are an important
preventive maintenance task for these
valuable assets. Unearthing minor problems
early allows small repairs to be made
before more extensive damage results.
Technicians frequently use rope access
techniques to complete the inspections
and perform minor repairs. For those of
us who don't particularly like heights,
the thought of sailing down a wind turbine
blade on ropes from the nacelle is
frightening, but for the technicians who
do this type of work, it's just another day
on the job.
Weather Can Be a Show Stopper
For even the most daring technician,
however, there are times when the work
simply can't be done. Wind, rain, temperature,
and humidity can all affect
the ability to complete maintenance as
scheduled. In some climates, up to 40%
of all canceled wind turbine maintenance
days are the direct result of adverse
weather conditions.
A new maintenance habitat (Figures 1
and 2) developed by UK-based GEV Wind
Power (GEV WP) may offer a solution.
The company has been working with
access platform provider Power Climber
Wind on its initial version. The habitat
attaches to blade access platforms (Figure
3) and allows users to control the
environment inside of the habitat using
blowers and heaters to create the
optimum temperature and humidity. The
apparatus could reduce time lost due to
weather and possibly extend the main18
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tenance
window beyond the traditional
period (May to October in the Northern
Hemisphere), returning a 1% to 2% increase
in annual energy production, according
to GEV WP's estimates.
" Habitat structures have worked well in
the oil and gas sector for many years and
we decided to migrate the idea across to
offshore wind, " said David Fletcher, managing
director of the GEV Group.
Prototype tests demonstrated the rapid
deployability of the habitat. Workers
were able to mount the habitat to the
platform in about five minutes. Once in
place, the whole structure was inflated
in less than three minutes. In midMarch,
GEV WP completed a successful
on-blade trial of its innovative seal at
the National Renewable Energy Centre
blade test facility in Blyth, Northumberland,
England. To see a short computeranimated
video of the process online,
visit: bit.ly/1BsG8F3.
Alastair Gadney, projects director for
GEV WP, told POWER that, although the
company doesn't have a large number
of data points yet, by using an offshore
wind farm that the company maintained
for a client last year, he was able to find
five production days that could have been
saved using the habitat. In addition, he
is confident that the maintenance season
could by extended by days or weeks on
1. A maintenance cocoon. The habitat
protects workers while blowers and heaters
create the optimal atmosphere for repairs.
Courtesy: GEV Wind Power
each end, adding more potential maintenance
days to the equation. In the end,
he suggested that the levelized cost of
energy could be improved through the
use of the habitat not only by reducing
maintenance costs but also by increasing
turbine availability.
Photo Scanning
While the habitat offers some significant
maintenance benefits, an even better option
when possible is to avoid the handson
inspection altogether. GEV WP offers
clients that option, using a panoblade
inspection system created by the Parisbased
company Cornis SAS.
The Cornis system uses a digital camera
(Figures 4 and 5) to capture images
of the entire blade surface from the
ground or offshore platform deck, circumventing
the need to work at heights
to complete inspections. The technique
is possible as the result of a unique
high-resolution photographic inspection
technology first developed for the
space industry.
One of the biggest advantages of the
system is the speed at which the inspec2.
Weather protection. Utilizing a habitat
could extend the window of opportunity
for maintenance. Courtesy: GEV Wind Power
3. Stable access. For blade inspection
and repair operations, suspended platforms
are said to offer a safe, productive, and costeffective
alternative to cranes, ground-based
lifts, and rappelling solutions. Courtesy: Power
Climber Wind
POWER | May 2015
http://www.bit.ly/1BsG8F3 http://www.powermag.com
POWER May 2015

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