POWER August 2015 - 55

WIND POWER
spar, and another, to a lightning strike), it said
it worked closely with customers to keep the
turbines running reliably and safely. According
to DNV GL, which has compiled blade
DNV GL suggests that manufacturing
defects are currently the leading cause of
blade failure, specifically, when blades are
not made to design specifications. Most
such as incorrect pitch setpoints, incorrect
shutdown sequencing, or failure to maintain
yaw alignment during high winds.
OEMs can take a number of steps to reDNV
GL suggests that manufacturing defects
are currently the leading cause of
blade failure, specifically, when blades are
not made to design specifications.
failure rates from 10 GW of operating wind
projects, between 1% and 3% of turbines in
North America require blade replacements
annually. Most of these replacements occur
within the first 10 years of operation, with the
highest failure rates usually occurring within
the first five years.
utility-scale wind turbine blades are manufactured
in several parts, which are then
bonded together in a secondary assembly
process, it notes.
But damage can also occur from lightning
strikes, during transportation and
handling, and due to operational factors
duce the risk of blade defects, DNV GL
says, including certifying their quality systems
to the ISO 9001 standard, ensuring
proper day-to-day detailed execution of
manufacturing and quality operations, and
automating processes such as fabric placement
and adhesive application.
The company acknowledges, however,
that to minimize wind turbine component
defects, much more research and development
is needed. Echoing concerns from
end users, it says that an enhanced knowledge
base would allow for more " precise
development " of quality acceptance criteria,
and that increased clarity on turbine
model-specific lightning protection system
performance is needed.
Finally, the industry would vastly benefit
from sharing information about blade
failure investigations and root cause analyses,
it says. (POWER would be happy to
report on such findings.) ■
-Sonal Patel is a POWER associate
editor
S&C congratulates Oncor on being awarded
Power Magazine's " Smart Grid Project of the Year "
©2015 S&C Electric Company 100-A1507
Come see the microgrid in person. Schedule your tour by e-mailing:
microgrid@sandc.com
CIRCLE 25 ON READER SERVICE CARD
August 2015 | POWER
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POWER August 2015

Table of Contents for the Digital Edition of POWER August 2015

Contents
POWER August 2015 - Cover1
POWER August 2015 - Cover2
POWER August 2015 - Contents
POWER August 2015 - 2
POWER August 2015 - 3
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POWER August 2015 - Cover3
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