1. Gefördert auf Grund eines Beschlusses des Deutschen Bundestages ProjektträgerKoordination Monitoring the power performance of an offshore WEC using nacelle-based wind measurements and the Langevin power curve Matthias Wächter, Patrick Milan, Philip Rinn, Joachim Peinke ForWind Center for Wind Energy Research Institute of Physics, Carl von Ossietky University of Oldenburg EWEA 2013 Vienna, 4.-7.2.2013

2. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 1 Challenge of wind power conversion Input Turbulent wind: Intermittent, extreme events Output »Turbulent« power Conversion Complex, nonlinear interaction

3. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 2 Wind energy conversion dynamics Highly dynamical process on short time scales Driven by turbulent wind How to obtain the response dynamics of WEC? Possible from wind and power data ~1Hz

4. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 3 Langevin power curve Drift function reflects average slope of power signal Drift field shows deterministic dynamics of energy conversion Stable fixed points constitute Langevin Power Curve Important properties Shows short-time dynamics (~1s) Quick detection of changes Multiple fixed points possible State-based vs. global averaging (as of IEC 61400-12) AV 4: REpower 5M

5. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 4 Langevin power curve monitoring AV 4: REpower 5M Daily LPC over 10 days, February 2011 Wind: nacelle anemometer Artifact caused by wind measurement »Unfortunately« no turbine anomalies here Changes in dynamical behavior are detected

6. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 5 Langevin power curve monitoring Example showing anomaly FAST simulation of WindPact 1.5 turbine Artificial pitch failure: one blade fixed to 45° LPC after 1000min of failure NOT AV 4 (Significant) Pitch failure clearly detected [Muecke, PhD Thesis, to be published]

7. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 6 Nacelle lidar-based Langevin power curve Lidar scanner developed by SWE, U Stuttgart Deployed at AREVA Wind M5000 prototype, BHV 1 day measurement AREVA Wind M5000 prototype Large potential of nacelle lidar-based power curve measurements

8. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 7 Nacelle lidar development at ForWind Prototype developed within “LIDAR II” at Marine Physics group, U Oldenburg Spinner integration Robust Cost-efficient Field testing early 2013

9. Wächter, Milan, Rinn, Peinke Power curve monitoring EWEA 2013 Vienna 8 Conclusions Langevin power curve suitable for monitoring of power performance Quick and clear detection of anomalies Large potential for nacelle-based lidar wind measurements Spinner-mounted lidar developed at ForWind Oldenburg Thank you for your attention! Thanks to: SWE U Stuttgart, REpower Systems SE, Areva Wind GmbH, and the RAVE initiative