Can we quantify performance changes based on nacelle power curves? EWEA Technology Workshop Analysis of Operating Wind Farms Bilbao, 14 April 2016

Transcription

1 Can we quantify performance changes based on nacelle power curves? EWEA Technology Workshop Analysis of Operating Wind Farms Bilbao, 14 April 2016 Anthony Crockford Philippe Cambron École de technologie supérieure Francis Pelletier Arista Jean Grassin JP Énergie Envrionnement 1

2 OVERVIEW Can nacelle power curves be used to quantify changes in wind turbine performance? With what accuracy? Introduction to nacelle power curves Possible uses Case study A: Repeatability Case study B: Instrument change Case study C: Wind turbine modification Discussion Alternative

3 1. INTRODUCTION Post-construction services Production data analysis Performance monitoring (3,000+ MW) Validation of upgrade packages Technical contract management Doctoral student Detection methods for wind farm underperformance Control charts & other statistical methods Independent renewable energy producer 163 MW in operation 59 MW in construction 350 MW in development

4 1. INTRODUCTION What can we learn from nacelle power curves? Nacelle wind speeds are often the only available measure source: windpower.org

5 1. INTRODUCTION What can we learn from nacelle power curves? Nacelle power curves can contain a lot of information Permit detection of issues & monitoring

6 1. INTRODUCTION What can we learn from nacelle power curves? Useful to add a time-axis or colour code

7 2. POSSIBLE USES What can we learn from nacelle power curves? Can detect incorrect operational modes

8 2. POSSIBLE USES What can we learn from nacelle power curves? Another useful tool to detect changes in power curve with time: control charts Developed by Philippe Cambron, Ph.D. student at ETS

9 2. POSSIBLE USES What can we learn from nacelle power curves? Detected a slow degradation in performance over 4 years, linked to blade erosion Degradation stabilised after blade cleaning and repairs

10 3. CENTRAL QUESTION Can nacelle power curves be used to quantify changes in wind turbine performance? With what accuracy? Upgrade packages Vortex generators Pitch optimisation Uprated power Software updates Underperformance Damage Blade erosion Curtailment Yaw error Aiming to quantify differences of 1-2%

11 3. CENTRAL QUESTION Can nacelle power curves be used to quantify changes in wind turbine performance? With what accuracy? Wind turbine operation Before Event After

12 4. CASE STUDY A How repeatable are nacelle power curves? Consider a wind farm of 70 identical wind turbines which have been operating continuously for three years, without any major changes to the wind turbines The energy content of the annual power curves, for a fixed wind regime, should remain the same Wind turbine operation Year 1 Year 2 Year 3

13 4. CASE STUDY A How repeatable are nacelle power curves? Inspected the inter-annual variability Found ± 2-3% variability between the energy content of the nacelle power curves, without any trends between years Wind turbine operation

14 5. CASE STUDY B The effect of instrument change The shape of this wind turbine s power curve has changed dramatically over time

15 5. CASE STUDY B The effect of instrument change The performance of the wind turbine appears to have increased significantly, following a specific event

16 5. CASE STUDY B The effect of instrument change The change can be traced to a change of anemometer type Wind turbine operation Before Event Replacement of cup anemometer with sonic anemometer After

17 6. CASE STUDY C The effect of wind turbine modification A wind farm owner has noticed the failure of glued-on blade elements, which are intended to improve the wind turbine performance The removal of these blade elements can be clearly detected in the nacelle power curve

18 6. CASE STUDY C The effect of wind turbine modification The nacelle power curve shows decreased power output after each blade element failure However, we found that the change is due to a change in the wind speed measurement, instead of a loss of wind turbine performance

19 7. DISCUSSION Can nacelle power curves be used to quantify changes in wind turbine performance? Case Study A: No changes in power curve Nacelle power curves are variable Air density corrections insufficient to remove interannual variability Case Study B: Instrument change Change of instruments can significantly change nacelle power curves Impacts possibility to monitor or compare performance before and after change

20 7. DISCUSSION Can nacelle power curves be used to quantify changes in wind turbine performance? Case Study C: Wind Turbine modification Nacelle wind speed measurements are sensitive to the blade shape Sensitivity could include changes to blade pitch, rotational speed, or other aspects of wind turbine control Any modifications need to be documented The effect on wind speed measurement needs to be evaluated

21 7. DISCUSSION Can nacelle power curves be used to quantify changes in wind turbine performance? Nacelle power curves can help to detect issues or to monitor wind farm performance However, nacelle wind speed measurements are highly sensitive to changes: Meteorological Instrumentation Wind turbine geometry or control system Use of nacelle power curves to quantify a change in power performance is risky, since the resulting uncertainty can be similar or larger than the performance change

22 8. ALTERNATIVE Or exclude nacelle wind speeds from the analysis Compare relative changes in power output between the modified wind turbine and a control wind turbine Control wind turbine Wind turbine operation Modified wind turbine Before Event After

23 8. ALTERNATIVE Advantages: Power measurements generally more accurate (Nacelle wind speed is not needed) No normalisation necessary for air density, turbulence intensity, wind shear, etc Statistical testing can demonstrate if measured change is significant Uncertainty propagation can be quantified Type B uncertainties mostly cancel out (instrument bias)

24 THANK YOU! Anthony Crockford avenue Desjardins, Montréal, QC, Canada