Maya Nissim: 2013 Sandia Wind Plant Reliability Workshop

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

Blade Maintenance for Reliability, an Owner/Operator Perspective 2

• 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


Blade Maintenance 2


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


Why?

When?

How?

Need to answer 3 basic Questions

Blade Maintenance Program Considerations 2


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






Considerations, When? 2








Considerations, How? 2




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


Goal is to maintain uniform & consistent categorization

Blade Damage Severity Rating 3

Cat 5

Cat 4

Cat 3 Cat 2


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.


Trailing Edge

Split tip, lightning damage, impact, damage during transport, de-bonding

Trailing Edge Examples

Historical Blade Damage 3

11 35%


Blade Shell (general)

Delamination (impact), de-bonding, EWV, lightning to shell

Blade Shell (general) Examples


13 27%


Other/Unknown

Most due to ice/storm conditions on blades, rest due to large corrective actions

Other/Unknown Examples


32 15%


Spar

Carbon fiber damage due to lightning &/or manufacturing defect

Spar Examples


24 9%


LPS

Blown receptors, burnt cable, missing or crooked receptors

LPS Examples


6 6%


Blade Root

Root crack, transverse crack

Blade Root Examples


10 6%


Leading Edge

LE bond line cracks, LE erosion

Leading Edge Examples


19 2%


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

Thank You!

Maya Nissim: 2013 Sandia Wind Plant Reliability Workshop

Technology

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