vestas.com Condition Based Maintenance of Vestas Offshore Turbines European Offshore Wind Conference & Exhibition 2009, Stockholm Jacob Juhl Christensen, Product Manager

2 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Agenda Condition Based Maintenance enabled by Condition Monitoring Technical and operational challenges in fleet-wide implementation Practical implementation of condition based maintenance in service organisation

3 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Condition Based Maintenance enabled by Condition Monitoring Condition Monitoring: Assessment of the "health" of a machine by analysis of measured signals (vibration, temperature, …) Estimation of time of failure  optimised planning of maintenance activities Breakdown (Ad Hoc) Preventive (Scheduled) Predictive (Condition based) Maintenance Strategies Condition Monitoring

4 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Condition Monitoring System Measurement system on WTG Drive Train:

5 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Condition Monitoring Information Flow

6 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Fault detection by historical trending of Fault Symptoms Failure modes Bearing Faults Coupling Faults Misalignment Faults Gear Faults Unbalance Support Structure Faults Examples of trended parameters Overall RMS High Frequency Bandpass Values Tooth Mesh Frequencies Bearing Frequencies etc.

7 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 How to achieve cost efficient condition monitoring on a large and geographically dispersed fleet ? Technical Challenges Events in each turbine can lead to a cascade of alarms Requirement: only one alarm per detected fault/severity level The severity of all alarms must be assessed Need for automated alarm management Operational Challenges Site managers need clear advice about how to plan service actions according to alarm severity.

8 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Automatic Alarm Management – NO Alarm Flooding Reliable fault detection requires monitoring of alarm limits per turbine. Alarm Flooding is avoided by filtering the fine grained alarm information down to one single alarm notice per physical fault. The Severity of the potential damage is estimated by the Alarm Manager from the indications in the alarm pattern. Final severity assessment performed by a diagnostic expert

9 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Severity classification – Actionable information Alarms are classified according to severity New alarms are issued only when a new severity level is reached A maximum of 4 alarm notices will be issued during the “lifetime” of a fault Each severity class specifies a lead time until recommended service action.

10 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Reporting – Clear advice about severity and estimated remaining life time Diagnose of detected potential failures are summarized in an Alarm Report Fixed report format with clear split between Observation Interpretation Assessment of maintenance needs

11 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Planning of service actions according to alarm severity Due to high mobilization costs, unnecessary turbine visits must be avoided. Rules for when to perform a turbine inspection as function of the alarm severity class must be defined. SeverityTypePlanning of inspection 1DangerWithin 24 hours or remote stop until access possible 2AlertASAP (within two weeks) 3AlertNext scheduled visit 4AlertNext scheduled visit 5GoodNo action 6SystemNext scheduled visit

12 | Condition Based Maintenance of Vestas Offshore Turbines, August 2, 2015 Summary Condition Based Maintenance on offshore turbines requires Online Condition Monitoring systems Automated Alarm management Alarms transformed into actionable information Planning of service actions according to alarm severity

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