Blade Reliability Case Study

Sandia Wind Turbine Blade Workshop

August 26, 2014

David Coffey

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Overview

• Snapshot of Iberdrola Renewables

• Overview of blade failure data

• Failure modes & repair rates

• Examples of carbon spar damage

• Examples of large crack repair

• Conclusions

• Improvement Goals

Aug 26, 2014

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Iberdrola Renewables - North America

Aug 26, 2014

Iberdrola Renewables develops, owns and operates wind plants throughout the U.S.

• 3000+ turbines• 56 wind farms • 18 states• 6+ GW capacity• 6 different OEMs• Rotor dia. 47-102 m

O & M Engineering:• Performance & Reliability• Continuous Improvement• Root cause analysis• Reliability centered maintenance• Failure rate projections• Repair specifications

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Snapshot of Iberdrola Renewables Fleet

Aug 26, 2014

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Blade Reliability

Aug 26, 2014

“Repair required” blade damages by year:• 7+ years• ~ 2600 reports• includes end of

warranty inspections, FM, operations etc.

Typical types of damage:• Lightning• Cracks• Impact damage • Surface/gel coat• LE erosion

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Blade Reliability

Aug 26, 2014

Top 5 damage types:1. Lightning2. LE Erosion - Light/medium/heavy3. Cracks4. Gel coat damage5. “Undetermined”

includes:• Lightning• Ice• Moisture

intrusion

Damages can be broken down further by location on blade

Top 9 represent 80%

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Blade Reliability

Aug 26, 2014

• 94% reported damage is repairable

• Repair rates for lightning have improved

• Carbon spar damage is still problematic

• Structural cracks are less likely to be repairable

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Examples of carbon spar lightning damage

Repairable today Repairable tomorrow?

Aug 26, 2014

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Examples of large crack repair

Aug 26, 2014

Upper shell

Lower shell

• Testing feasibility of large crack repairs• Will the repairs last?• Is it economical?

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Blade Reliability

Conclusions:1. Overall blade damage rates are higher than expected

2. Lightning damage, LE erosion, Gel coat damage account for 80% of damage reported

3. 94% total repair rate for all blade damages– 6% replacement rate drives cost of ownership

4. Ongoing cost of ownership for carbon spar blades is higher than other blade types– Actively seeking improved protection and repair options.

Aug 26, 2014

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Improvement Goals:

1. Blade damage– Improved data reporting – standard method of damage categorization– Continue to refine and improve damage reporting data base

• Clear and consistent criteria for run vs. stop decisions• Clarify repair criteria

– Up tower repair – types and severity– Ground repair – economic feasibility of repairs

2. Lightning protection:– Design and test standards

• Improvements needed to IEC61400-24 lightning protection efficiency calculations

– LPS system enhancements

3. Large crack repair

4. Carbon spar repair

Aug 26, 2014

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Thank You!