Anemometer Calibration Requirements for Wind Energy Applications

Transcription

1 Anemometer Calibration Requirements for Wind Energy Applications Presented y: Rachael Ishaya ryza Wind Lab, Inc., Fairfield, California American Meteorological Society 17th Symposium on Meteorological Observations and Instrumentation June 11, 014 Westminster, Colorado

2 Outline Importance of Wind Sensors in Wind Energy Wind Sensors Used in Wind Power asic Anemometer Calibration Applicable Test Standards Test Facility Requirements Facility Performance Evaluation Calibration Uncertainty Summary Rachael Ishaya, President

3 Importance of Wind Sensors in Wind Energy Wind Plant Operations alidate wind turbine power output Control start-up and shut-down Wind Turbine Performance Evaluations Power curve (wind turbine power output as a function of wind speed) Wind Energy Site Assessments Use power curves and wind distributions to estimate annual energy production for power purchase agreements Turbine Output Power (kw) Wind Speed (m/s) Rachael Ishaya, President Rated Power Turbine Power Sample Turbine Power Curve 1.5 MW rated power reached at ~1 m/s Power estimated at lower wind speeds can be as much as 30% error depending on curve

4 Wind Sensors Used in Wind Power Wind turbines are designed to generate power from direct incoming flow Key measure from a wind sensor is the magnitude of the horizontal wind speed component Rachael Ishaya, President

5 asic Anemometer Calibration Anemometer Output Controlled Reference Speed Rotation rate (i.e., Hz or rpm) Wind generated from a controlled wind tunnel Analog voltage or conditioned digital signal Reference Pitot-static tubes Reference Speed, U [m/s] Anemometer Frequency, f [Hz] Rachael Ishaya, President Anemometers are designed to be linear instruments Perform a Least Squares Fit Linear Transfer Function

6 Applicable Test Standards ASTM D5096-0, Standard test method for determining the performance of a cup anemometer or propeller anemometer ASTM D , Standard test method for determining the performance of a sonic anemometer/thermometer ISO , Meteorology Wind measurements Part 1: Wind tunnel test methods for rotating anemometer performance ISO 166, Meteorology Sonic anemometers/thermometers Acceptance test methods for mean wind measurements IEC , Wind turbines Part 1-1: Power performance measurements of electricity producing wind turbines IEC , Wind turbines Part 1-: Power performance of electricity producing wind turbines using nacelle anemometry General requirement is to perform anemometer calibrations in a uniform-flow, low-turbulence wind tunnel Rachael Coquilla, President rvcoquilla@bryzawindlab.com NCSL International Aug 1, 01 Anaheim, CA

7 Test Facility Requirements Wind Tunnel Characteristic Speed Range Standards Requirements IEC (4-16 m/s); Others based on % of application speed Flow Uniformity IEC (<0.%); Others (<1%) Wind Gradient IEC (<0.%) Turbulence Intensity IEC (<%); Others (<1%) Density Uniformity ASTM D5096-, ISO (<3%) Data Acquisition Model lockage Repeatability Interlaboratory Comparison Resolution 0.0 m/s, minimum sampling 10 Hz, duration sec 10% max for open test sections, 5% max for closed test sections IEC (<0.5% at 10 m/s test speed) IEC (within 1% in 4-16 m/s test speed range) Rachael Ishaya, President

8 Test Facility Requirements Common Wind Tunnel Configurations Open-circuit, suction or Eiffel-type Open-circuit, blower-type Contraction Test Section Diffuser Fan Motor lower Motor Settling Chamber Contraction Test Section Rachael Ishaya, President

9 Facility Performance Evaluation AIAA R , Calibration of Subsonic and Transonic Wind Tunnels General concept is to define dynamic pressure in test section according to the pressure drop generated by the wind tunnel contraction section. P 1 P Inlet Contraction Section Test Section Diffuser Section Fan Motor Rachael Ishaya, President

10 Facility Performance Evaluation Airflow 50 hp fan-motor.5 ft.5 ft FD 5 ft Reference speed measurement: Pitot-static tube system (as defined by IEC ) Four Pitot tubes with sensing tips positioned at test section inlet where total and reference ports connected to an MKS 10AD transducer. Rachael Ishaya, President

11 Facility Performance Evaluation Pitot-Static Tube System General elocity Equation p = ρ Differential pressure from Pitot-static tube Density of humid air ρ = R 1 * T [ T PM φe ( M M )] air Ambient temperature Ambient pressure air Relative humidity w Rachael Ishaya, President

12 Facility Performance Evaluation elocity profiles at center of test section from traversed Pitot tube. 1) Profiles mean speed settings from 4 to 6 m/s showed an average test section uniformity within /-0.%. ) Preliminary indication of less than 0.% turbulence. 3) Difference in wind speed between center of test section to reference Pitot-static tubes at inlet averages to 0.014%. Rachael Ishaya, President

13 Facility Performance Evaluation Second Wind C3 1/ diameter mounting stand lockage Ratio A A C TS 3 % Empirical lockage Correction k b 1 AC = 1 3 = A TS Test performance requirements according to IEC Calibration test speeds: 4 to 16 m/s at 1 m/s increments Repeatability (<0.5% at 10 m/s) within 0.% for 5 repeated tests Interlaboratory Comparison (/-1% at 4-16 m/s) 1% average variation in comparison to an accredited wind tunnel laboratory in Denmark Rachael Ishaya, President

14 Calibration Uncertainty Anemometer calibration uncertainty consists of the propagation of errors from three general areas cal ( U ) ( U ) ( U ) U = IUT LR Reference wind speed Test sensor output Calibration linearity Reference Speed [m/s] IUT Output [Hz] Uncertainty in each area includes systematic or ( ) Type errors ( i ) and random or Type A errors (S i ) Rachael Ishaya, President U = Coverage factor at 95% confidence i i ts i

15 Calibration Uncertainty U = Uncertainty in reference wind speed ( ) Analyzed from Pitot-static tube velocity equation ts p = p = Chkbkc ρ ρ ρ = 1 R* T T [ PM φe ( M M )] air air w = f (M air, M w, k b, k c, C h, R*, P, T K, p, φ) Rachael Ishaya, President

16 Rachael Ishaya, President Calibration Uncertainty Uncertainty in reference wind speed ( ) ts U = * * = φ φ p T P R C k k p T P R C h k c k b h c b = φ φ S S p S T S P S p T P INDEPENDENT ARIALES (exact values defined by NIST) M air andm w Measured P, T, φ, p Analyzed k b, k c, C h, R* DEPENDENT ARIALES

17 Calibration Uncertainty U = Uncertainty in test sensor output ( ) Type errors are acquired from data acquisition system. Type A errors are quantified by the standard deviations in the test sensor reading. IUT IUT ts IUT Uncertainty in calibration linearity U ( ) LR = t res Reference Speed [m/s] IUT Output [Hz] Speed Residual [m/s] IUT Output [Hz] Rachael Ishaya, President

18 Calibration Uncertainty Calibration Uncertainty for the C3 Anemometer m/s 0.0 Uncertainty (m/s) m/s Reference Speed C3 Output Transfer Function Overall Reference Speed (m/s) Rachael Ishaya, President

19 Summary Key Considerations for an Anemometer Calibration Program 1) Perform tests in a controlled, uniform-flow, lowturbulence wind tunnel as required by test standards ) erify wind tunnel performance through velocity surveys 3) Qualify ability to perform wind sensor calibrations lockage evaluation Test repeatability Interlaboratory comparison 4) Document the uncertainty analysis For more information: Rachael Ishaya, President