Blade Maintenance for Reliability, an Owner/Operator Perspective

1. Blade Maintenance for Reliability, an
Owner/Operator Perspective
An overarching strategy for maintaining blades including suggested timelines,
methods, procedures, and tools to inspect, document, maintain, and repair blades.
Maya Nissim
Turbine Performance Engineer, EDP Renewables
August 13, 2013

2. Blade Maintenance for Reliability, an Owner/Operator Perspective
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• EDP Renewables North America LLC develops, constructs, owns, and operates wind farms
throughout North America
• 3rd largest renewable operator in the US and ranked 4th in net installed capacity
• Currently operating over 3,800 MW at 29 wind farms in 11 states with more than 2,100 turbines in
operation and approximately 66 million hours of operational history
• Headquartered in Houston, Texas
• Performance Engineering group part of Asset Operations & responsible for:
• Continuous improvement of turbine & main component performance & reliability
• Fault reduction
• Predictive maintenance
• Root cause analysis
• Failure trending and projections
• Component repair specifications
About EDP Renewables North America 1

3. Blade Maintenance for Reliability, an Owner/Operator Perspective
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Blade Maintenance 2

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Problem Statement:
WTG blades are a vital main component whose role is to extract energy from the wind in order to
ultimately generate electricity. It is a valid assumption that blade damage has major impact on
our fleet performance and ability to achieve its production potential in forms of turbine efficiency,
downtime and cost of the major component repairs and replacements.
Objective:
Develop an overarching Asset Operations strategy for maintaining blades in EDPR’s fleet, including
suggested timelines, methods, procedures and tools to inspect, document, maintain, and repair
blades
Criteria:
The recommended strategy must be cost-effective and lead to long-term savings.
Motivation
Blade Maintenance Program Development 2

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Why?
When?
How?
Need to answer 3 basic Questions
Blade Maintenance Program Considerations 2

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Why?
Explore the assumption that preventative & proactive maintenance of blades will benefit the
company
•Economics of blade maintenance
•Historic blade failure rates & cost analysis
•Summary of known blade damage to-date
Considerations, Why? 2
When?
•Inspection/maintenance timeframe & frequency
How?
•Possible Resources
•Up-tower vs. down-tower; visual vs. physical
•SOP & Change Management Process
•Measure Success

7. Blade Maintenance for Reliability, an Owner/Operator Perspective
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Why?
Explore the assumption that preventative & proactive maintenance of blades will benefit the company
•Economics of blade maintenance
•Historic blade failure rates & cost analysis
•Summary of known blade damage to-date
Considerations, When? 2
When?
•Inspection/maintenance timeframe & frequency
How?
•Possible Resources
•Up-tower vs. down-tower; visual vs. physical
•SOP & Change Management Process
•Measure Success

8. Blade Maintenance for Reliability, an Owner/Operator Perspective
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Why?
Explore the assumption that preventative & proactive maintenance of blades will benefit the company
•Economics of blade maintenance
•Historic blade failure rates & cost analysis
•Summary of known blade damage to-date
Considerations, How? 2
When?
•Inspection/maintenance timeframe & frequency
How?
•Possible Resources
•Up-tower vs. down-tower; visual vs. physical
•SOP & Change Management Process
•Measure Success

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Blade Data Inputs 3
Blade Maintenance
Program
Independent
Observations
EOW Inspections Lightning Events
Database
Determine
blades to
inspect
Determine
blades to
inspect
Vaisala
lightning
data
Generate
inspection
report and
email request
Site inspects
all blades on
specified
turbine
3rd party
inspects
specified blades
3rd party
inspects
specified blades
3rd party
creates
inspection
report
3rd party
creates
inspection
report Site inspection
report
generated
Sites inspect
blades of
specified
turbine
Site
inspection
report
generated

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Goal is to maintain uniform & consistent categorization
Blade Damage Severity Rating 3
Cat 5
Cat 4
Cat 3Cat 2

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Overview of blade failure downtime data & typical blade damage types*
Historical Blade Data 3
Blade Failure Mode Frequency
Trailing Edge
Blade Shell (general)
Spar
Blade Root
Leading Edge
*Data taken from EDPR’s offline turbine database so only captures turbines that were taken offline for the
respective blade issues and thus does not necessarily capture all issues present on running turbines.

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Trailing Edge
Split tip, lightning damage, impact,
damage during transport, de-bonding
Trailing Edge Examples
Historical Blade Damage 3
1135%

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Blade Shell (general)
Delamination (impact), de-bonding, EWV,
lightning to shell
Blade Shell (general) Examples
Historical Blade Damage 3
1327%

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Other/Unknown
Most due to ice/storm conditions on
blades, rest due to large corrective actions
Other/Unknown Examples
Historical Blade Damage 3
3215%

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Spar
Carbon fiber damage due to lightning &/or
manufacturing defect
Spar Examples
Historical Blade Damage 3
249%

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LPS
Blown receptors, burnt cable, missing or
crooked receptors
LPS Examples
Historical Blade Damage 3
66%

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Blade Root
Root crack, transverse crack
Blade Root Examples
Historical Blade Damage 3
106%

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Leading Edge
LE bond line cracks, LE erosion
Leading Edge Examples
Historical Blade Damage 3
192%

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Concluding Remarks 4
EDPR’s goals for the long term performance and care of our rotor blades:
• Proactive annual visual inspection of a percentage of blades
• Uniform & consistent damage categorization scale
• Documentation of all findings
• Prioritize repair of blades found to have damage and conduct at optimal time to avoid
catastrophic failure
• Proactive lightning inspections
• Prescription of “next steps” (i.e. re-inspection interval, repair)
• Continuously seek to improve the life of our blades by performing maintenance as needed
as well as proactively seek new methods for protecting them from excessive wear

20. Thank You!