edition 1.0 2020-12-08 iecre operational documentiecre od-551-24 edition 1.0 2020-12-08 iecre...

IECRE OD-551-24 Edition 1.0 2020-12-08

IECRE OPERATIONAL DOCUMENT

Assessment of RETLs for “Power performance measurements of electricity producing wind turbines” according to IEC 61400-12-1 Ed2.0: 2017-03

IEC

RE

OD

-551

-24:

2020

(EN

)

IEC System for Certification to Standards relating to Equipment for use in Renewable Energy applications (IECRE System)

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CONTENTS

CONTENTS ............................................................................................................................ 2 1 Introduction ..................................................................................................................... 3 2 Review of reports issued ................................................................................................. 3 3 Review of internal procedures ......................................................................................... 3

3.1 Identification of key procedures .............................................................................. 3 4 Inspection of field test ..................................................................................................... 4 Annex A – Checklist ................................................................................................................ 5

IECRE OD-551-24:2020 © IEC 2020 – 3 –

Introduction

This OD covers the assessment of a power performance test for Test Laboratories who want to get this competence area recognised under IECRE.

Specifically, this ODs covers the standard assessment as per the WE-OMC Rules of Procedure. The scope of this OD is the IEC 61400-12-1 Ed2.0:2017 standard with the following Annexes excluded:

• Annex F: Wind tunnel calibration procedure for anemometers

• Annex I: Classification of cup and sonic anemometry

• Annex J: Assessment of cup and sonic anemometry This scope is referenced in this OD as 'the standard'. The scope of this OD is limited to the application of the HH wind speed and REWS methodologies excluding the application of RSD.

The standard assessment is based on four elements:

– A review of three reports issued by the Applicant within the last three years – Successful participation in a power performance proficiency test – Review of key internal procedures – Witnessing of one power curve test in process, according to chapters 3 and 4, and also

Annex A in this document In this document, the Applicant is the organisation asking for an assessment according to this OD. The applicant may be an already recognised RETL or an organisation not yet recognised under IECRE for this competence area. An RETL refers to an IECRE recognised Test Laboratory.

Review of reports issued

In order to have three reports reviewed, the Applicant shall submit an overview of reports submitted the last three years with the IECRE logo. In case the assessment is for a candidate RETL or the Applicant has issued fewer than three IECRE test reports for power performance testing, the Applicant shall submit to the IECRE Secretariat a list of reports issued that state compliance with the standard

The Lead Assessor, together with the Technical Assessors and/or experts, shall select from this list three reports. These reports have to be submitted to the IECRE Secretariat by the Applicant.

The reports shall be reviewed for compliance with the standard, as per the checklist in Annex A of this OD. A filled-out version of the checklist shall be included in the final assessment report.

Review of internal procedures

3.1 Identification of key procedures The following procedures should normally be checked:

– Installation of anemometers in the meteorological mast – Installation of wind vanes in the meteorological mast – Installation of power measurement devices – Records (installation and/or maintenance reports, …) management. – Data integrity management and quality check procedures – Calculations and reporting. – Calculation of uncertainty A review of facilities where equipment is prepared for outside use may be part of the assessment.

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Inspection of field test

As part of the assessment the assessment team shall inspect one test in the field to establish:

1) Compliance with the standard 2) Compliance with the key internal procedures as defined under section 3 of this OD 3) Identify further process or technical issues that could affect the result of the test

In the case that a field test is not available or the effort for the assessment is unjustifiable, the assessed RETL together with the assessment team shall agree upon a solution on how to carry out this field inspection.

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Annex A – Checklist 1

Please note that this checklist is used for reviewing reports as well as the applicant's internal procedures and may be used as well for the on-site inspection 2 3

Item no

Reference to section] in standard

Statement [/Requirement from standard]

Requirement [/Checks and expert guidance] Reported / Inspected

Finding Classification (Minor/Major) (*)

1. Identification and description of the specific test turbine, test conditions and configuration (Chapter 5, 6, 7 / Reported according to 10.a) 1.1. 5

7.2.1

Power performance method overview Wind speed – General

Is it stated which configuration from Table 1 has been followed in the performance of the test?

Does it meet the considerations of Table 2?

1.2. 6.1 General Have there been specific test conditions worth mentioning, such as snow and ice (which may affect turbine and sensors), freezing weather (affecting the sensors and cup classification), strong hail or other that might influence the data treatment and results?

1.3. 6.2 Wind turbine and electrical connection

- Are the wind turbine main characteristics documented according to 10.a) from 1) to 8) ? -> items 1.4+ next. - Is it documented how that information is obtained (manufacturer’s certificate, in-situ verification, …)?

1.4. 10 a 1) Identification of the turbine configuration (Typically provided in the form of a Manufacturer certificate)

Wind turbine make, type, serial number, production year reported? 1.5. 10 a 2) Rotor diameter D and description of the reference method used documented? 1.6. 10 a 3) RPM or RPM range reported? 1.7. 10 a 4) Rated power and Rated Wind Speed reported? (HM to the team: Can we discuss the definitions

of these?)

1.8. 10 a 5) Blade data reported? 1.9. 10 a 6) Hub height and tower type reported? 1.10. 10 a 7) Control system reported? 1.11. 10 a 8) Grid conditions reported 2. Test site (Chapter 6.3 and Annexes A and B / Reported according to 10.b) 2.1. 6.3 Test site 2.2. 6.3.1 General Is the test site described and reported according to 10.b from 1) to 5) -> covered in items 2.8

onwards. N/A

2.3. 6.3.2 Location of the wind measurement equipment

Is the wind measurement equipment located within a distance between 2 and 4 times the rotor diameter D of the tested turbine (preferable 2.5D) / In case of vertical axis wind turbine, according to Figure H.1 ?

2.4. 6.3.3 Measurement sector Note: Calculations related to the measurement sector free of wakes to be assessed through a LPT. Note: analysis of sector determination according to Annex A is treated in items 2.13 onwards.

2.5. Has the measurement sector been reduced beyond the limits obtained according to Annex A (includes particular case in item 2.31)? If so, has this been justified and documented?

2.6. 6.3.4 Correction factors and uncertainty due to flow distortion originating from topography

Note: Calculations related to terrain assessment will be assessed through a LPT Note: terrain analysis according to Annex B is treated in items 2.29 onwards. Note: Uncertainties without site calibration: covered under items 6.12/6.49 of this OD.

2.7. If Site Calibration is performed: have the flow correction factors been used for the power curve? 2.8. 10 b 1) Description of the test site Photographs of the measurement sectors available 2.9. 10 b 2) Map showing the turbine and the mast covering at least a range of 20 D including terrain,

obstacles, other turbines and topography

2.10. 10 b 3) Site assessment results with an evaluation of the valid sector presented? 2.11. 10 b 4) In case a site calibration is performed: Are the limits of the available sector reported? 2.12. 10 b 5) Is a table of coordinates and elevation of the tested turbine, as well as significant obstacles

considered presented?

2.13. A.1 General Has the two step procedure been implemented in the order: a) Evaluation of influences first and b) evaluation of obstacles second?

2.14. A.1 General Option: Are objects (including orographic elements) whose height is more than half of its width considered as obstacles?

2.15. A.1 General Has the influence of the obstacles been evaluated over: - Tested wind turbine? - Met mast?

2.16. A.1 General Has the “valid sector” as per annex A been used in the assessment following following Annex B?

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2.17. A.2 – A.4

Requirements regarding neighbouring and operating wind turbines

Has the influence of operating (at any time during the test) wind turbines been assessed according to A.2?

2.18. Has the wake influence of all the operating wind turbines evaluated according to A.4 and Figure A.1?

2.19. Are all the operating wind turbines documented and the dimensions to be considered reported: Dn, Ln?

2.20. In case of stopped wind turbines, have they been assessed according to A.4? 2.21. A.3 – A.4 Requirements regarding

obstacles Method for calculation of sectors to exclude

Is it stated whether the evaluation of neighbouring obstacles has been performed either as part of the orography (Annex B) or as described in A.2?

2.22. Has the relevance of all the obstacles (e.g. buildings, trees, stopped wind turbines) near the wind turbine or WME been evaluated according to Table A.1?

Has that evaluation been performed both in the surroundings of the wind turbine and the WME according to Table A.1?

2.23. When the obstacle has been determined as “significant” according to Table A.1, has the excluded measurement sector been calculated according to A.4 (for every obstacle)?

2.24. Are all the neighbouring obstacles documented and the dimensions to be considered reported: L, De, lh, lw?

2.25. In case there are stopped turbines found to be significant obstacles, has the tower foot diameter and the upper blade tip height been used to determine the corresponding sector to exclude?

2.26. Has the wind turbine under test been evaluated with respect to its wake influence on the WME? 2.27. A.5 Special requirements for

extended obstacles Has any extended obstacle (within a distance of less than 4L from centre of the wind turbine under test or from the wind measurement equipment, which extend more than 50 m in any horizontal direction) been assessed according to A.5:

- Divided into partial obstacles meeting the criteria of A.5 - Evaluated each of the partial obstacles according to Table A.1 - Calculated the excluded sector (if significant obstacle) according to A.4

2.28. Are these extended obstacles documented and the dimensions to be considered reported: distance, dimensions?

2.29. B Assessment of terrain at the test site

Has the grid resolution of the digital model of the terrain used for the terrain assessment been reported (30 m or finer)

2.30. B Has the terrain been evaluated according to Annex B and taking as centre for the evaluation the centre of:

- Tested wind turbine? - Wind measurement equipment

2.31. Annex B, Comment A in table B.1 with footnote no 24

Sector restriction Where there are significant terrain variations at the borders of the measurement sector: Has a further sector restriction been applied on top of the one determined in the Annex A evaluation step? The standard suggests considering this. (Particular case of item 2.5.)

2.32. Table B.1 Have the results of the terrain assessment been reported as per Table B.1 (more documentation -results of the assessment- than whether the site meets or fails to meet the requirements is expected)

3. Test equipment (Chapter 7 / Reported according to 10.c.) 3.1. 7.1 Electric power Has the net electric power been measured using a power measurement device, based on

measurement of current and voltage on each phase (e.g. power transducer)? If not the case the equivalent principle should be described.

3.2. How many power signals are measured (Rotor / Stator / Consumptions may be separate) 3.3. Is the power measurement performed on all phases? 3.4. Was the class of current transformers 0.5 or better (according to IEC 61869-2)? Was this minimum

class requirement respected for the whole range of the measurement?

3.5. Was the class of voltage transformers, if any, 0.5 or better (according to IEC 61869-3)? 3.6. Was the class of power transducer, if any, 0.5 or better (according to IEC 60688)?

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3.7. If the power measurement device is not a power transducer, was the accuracy documented and equivalent to class 0.5 or better?

3.8. Has the range of power measurement device been captured data from all instantaneous positive and negative power values of the wind turbine ? Has this been monitored during the measurement campaign and at the end and reported if power peak outside of this range occurred?

3.9. Has the power transducer been calibrated to traceable standards ? Calibration certificates to be provided and checked by assessment team. Note: since the RETL must be ISO 17025 accredited, it is assumed that all the sensors in the measurement chain must be calibrated by an ISO accredited calibration institute.

3.10. Is the power measurement located at a point where it accounts for self consumption? 3.11. 7.2 Wind speed 3.12. 7.2.1 General Has the primary wind speed used for power curve derivation been measured at hub height? 3.13. Is the measurement setup and configuration identified in Table 2? Is the correct measurement

technology and configuration adapted for the terrain type, according to Table 2?

3.14. 7.2.2 General requirements for meteorological mast mounted anemometers

Note: section from item 3.15 to 3.19 to be assessed for each cup or sonic anemometer having its measurements used for the results of the test.

3.15. Does the anemometer have a class of minimum 1.7A or 1.7C in case of flat site?

3.16. Does the anemometer have a class of minimum 1.7S or 2.5B or 2.5D in case of terrain where site calibration is required?

3.17. Have the anemometers been calibrated before the measurement campaign by an IECRE recognized lab? Calibration was performed according to Annex F?

3.18. If the validity of the calibration of the anemometers has been verified by post calibration, has only

the pre calibration been used to perform the power performance test?

3.19. Note: in-situ and post-calibration are covered in the uncertainty part of this check-list, in items

6.33 onwards. N/A

3.20. 7.2.2 / C.3.2

Have all applicable items from 3.15 to 3.19 been assessed for each relevant anemometer? (see item 3.14). In case of site calibration, this requirement affects both masts for that phase.

3.21. 7.2.3 Top-mounted anemometers Note: "Was the top anemometer mounted on the mast and boom according to Annex G?" is

covered in items 3.72 to 3.82. N/A

3.22. Was the height of the top anemometer measured with a controlled measurement device and the uncertainty calculated and documented?

3.23. Is the uncertainty of the measurement of the height above ground level less than 0.2m?

3.24. Option: Has the ground level been considered as mean elevation over a radius of 2 m around the mast base or 5 m radius around the turbine base?

3.25. Note: "Has the control anemometer been installed in accordance with Annex G?” is covered in items 3.81 to 3.105.

N/A

3.26. 7.2.3 / C.3.2

Top-mounted anemometers / Site calibration

In case of Site Calibration: are previous items from 3.21 onwards fulfilled by both met masts for this phase?

3.27. 7.2.4 Side-mounted anemometers Has the mounting of the side-mounted anemometers followed Annex G?

3.28. Has the height of each side mounted anemometer been measured and verified using controlled methods?

3.29. Option: Has any correction been applied to the wind speed measured by side – mounted sensors?

3.30. Have the booms at different heights been installed with same orientations? Option: Has the effect of the mast on the sensors been assessed and kept below 1%?

3.31. Option: In case of freestanding mast, have the booms been adapted to keep the disturbance similar at all levels?

3.32. Option: Has the alternative option of installing a second anemometer at each height been used? Has the wind speed difference between the two anemometers been within 1%?

3.33. 7.2.4 / C.3.2

Side-mounted anemometers / Site calibration


3.34. 7.2.6 Rotor equivalent wind speed Option: In case REWS has been calculated, has it been determined from at least 3 measurements

at three different heights according to the options in 7.2.6 and Figure 2 in 7.2.8

3.35. 7.2.7 Hub-height wind speed Does the measurement set-up correspond to one of the 3 allowed options? 3.36. Note: uncertainties for shear and veer are covered under items 6.61 onwards. N/A 3.37. Is the hub-height wind speed measurement performed within 1% of hub-height?

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3.38. 7.2.7 / C.3.2

Hub-height wind speed – Site Calibration

In case of site calibration: are the previous items from 3.35 onwards fulfilled by both met masts for this phase?

3.39. 7.2.8 Wind shear measurement – General

Wind shear measurements performed by side-mounted anemometers.

3.40. Measurement height for wind shear measurement distributed symmetrically around hub height and evenly over the vertical range.

3.41. Are the requirements of figure 2 fulfilled, i.e. having at least three levels at HH+/-1%, a second one between H-R and H-2/3R and a third, upper one between H+2/3R and H+R?

3.42.

Are the conditions in figure 3 fulfilled? I.e. a side mounted anemometer near the top and a second side mounted anemometer with the same orientation, type and boom length between heights H-R and H-2/3R?

3.43. 7.2.8 / C.3.2

Wind shear measurement – Site Calibration

In case of site calibration: are the previous item from 3.40 onwards fulfilled by both met masts for this phase?

3.44. 7.3 Wind direction Has it been documented which type of sensors has been used: Wind vane, 2D or 3D ultrasonic? 3.45. If an ultrasonic has been used: is it applied in conjunction only with a wind vane for control?

3.46. Option: Has the average wind direction for each ten minutes sample been derived by vector averaging?

3.47. Option if used: Has the dead band of the wind direction sensor been identified and data excluded when in that range?

3.48. Note: “Has the combined uncertainty of the wind directions sensor proved to be less than 5 degrees?” is covered in the uncertainty section of this OD under item 6.72.

N/A

3.49. Has the wind direction sensor been calibrated?

3.50. 7.3 / C.3.2 Wind direction – Site Calibration In case of site calibration: are the previous items from 3.44 onwards fulfilled by both met masts

for this phase?

3.51. 7.4 Air density Has the relative humidity measured or assumed to be 50%? 3.52. Has the air density been calculated using Equation 12 in 9.1.5?

3.53.

Hub height tower case: Is the air temperature sensor mounted within 10 m of the HH? Small tower case: Was any correction applied? Were Annex G requirements applied for shorter masts?

3.54. Is the pressure sensor mounted within 10 m of HH and are corrections applied according to ISO 2533?

3.55. Option: Is the humidity sensor mounted within 10 m of the HH?

3.56.

Have the humidity, temperature and pressure sensor been calibrated before the measurement campaign? Have all optional settings been considered in the later assessment of uncertainty? Note: since the RETL must be ISO 17025 accredited, it is assumed that all the sensors in the measurement chain must be calibrated by an ISO accredited calibration institute

3.57. 7.5 RPM/Pitch No requirements. Option: Is RPM measured and the need for recording it documented?

3.58. 7.6 Blade condition No requirements. Option: Is blade condition monitored? If so how is it done and what statuses

have been observed before and during the test?

3.59. 7.7 Wind turbine control system Has the control software version been documented?

3.60.

Is there a list of statuses and their definition available and reported? Are they sufficient as to identify the status of the turbine and to allow the rejection criteria according to 8.4? Note: the scope of this question is only the relevancy of the signals. The corresponding data rejection is covered in points 5.9 to 5.18

3.61. 7.8 Data acquisition system Does the DAS have at least a sampling rate of 1 Hz? (Note: Sampling relates to the data collection

to the DAS, some signals require much higher internal sampling like the power transducers)

3.62. Note: Data collection as per 8.3 is covered in items 5.5 onwards. N/A

3.63. Has the calibration and accuracy of the DAS been verified by means of end to end line test, injecting known signals from calibrated sources?

3.64. 10. c) Reporting format

3.65. 10 c 1) Is there a list of all sensors used with serial numbers, and documentation showing the calibration

reports, transmission lines and DAS?

3.66. 10 c 2) Is there a schematic drawing of the met mast showing dimensions of the mast and booms and

document the compliance with Annex G.

3.67. 10 c 3) Is it documented if post calibration or in situ was performed to maintain the calibration of the

anemometers during the measurement campaign for met mast? Note: details on how the

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corresponding analysis is performed, are covered in the uncertainty part of this check-list, in items 6.33 onwards.

3.68. Annex G 3.69. G.1 General

Is there a control anemometer mounted close to the primary anemometer?

3.70. Documentation required: Primary anemometer was single top-mounted or side-by-side?

3.71. G.1 / C.3.2

General mounting / Site Calibration


3.72. G.2 Single top-mounted

anemometer Is the anemometer at least 1.5 meters above the met mast and any other sources of flow disturbance?

3.73. Are there any parts of the mast and ancillary outside of the 11:1 half cone (down to a distance of 4 m below cups)?

3.74. Is the diameter of the mounting tube smaller or equal to the diameter of the sensor? Same as used during the calibration and classification in the Wind tunnel? Round in section?

3.75. Is the length of the mounting tube plus sensor body (measured to the anemometer cups) higher than 0.75m?

3.76. Is the additional tube up to 1.5 m (below the cups) thinner than anemometer body?

3.77. Is the sensor cable run inside the tube or, and where not possible, wound spirally around the supporting tube?

3.78. Was the anemometer calibrated with the same cable and routing and installed on the mast?

3.79. Was the anemometer and mounting tube inclination from vertical less than 2 degrees? How was this verified and documented?

3.80. Is the 1:11 cone condition including the 4 m minimum distance requirement of Figure G,1 fulfilled?

3.81. Is the control anemometer for a top mounted anemometer a side mounted one installed between 4m and 6 m below the primary?

3.82. G.2 / C.3.2

Single top-mounted anemometer / Site Calibration

In case of Site Calibration: are previous items from 3.72 onwards fulfilled by both met masts for this phase, where applicable?

3.83. G.3 Side-by-side top-mounted

anemometers Is the minimum distance between the horizontal boom and the measurement volumes at least 20 d of the horizontal boom?

3.84. Are both the horizontal and vertical parts of the boom of round cross-section?

3.85. In case a Side-by-side top section is used: Is the horizontal separation between both sensors between 2.5 and 4 meters?

3.86. Are there any parts of mast structure outside of the 4meter 11:1 half cone with the vortex in the midpoint between the two top-mounted anemometers?

3.87. Has the influence of one anemometer on the other assessed by means of shadow analysis and sector restricted? Has this been documented?

3.88. Is the uncertainty due to distortion from other sensors, lightning finial, mast and booms been determined and documented?

3.89. G.3 / C.3.2

Side-by-side top-mounted anemometer / Site Calibration


3.90. G.4 Side-mounted instruments

3.91. G.4.1 General Is the flow distortion at the anemometer cup location due to booms below 0.5%? Has this been

calculated or based on distance from horizontal boom?

3.92. Are the anemometers mounted on tubes with same diameters as used in calibration?

3.93. Are the wind vanes mounted at a distance from the mast of at least half the one used for anemometers?

3.94. Are there at least 20 boom diameters vertical separation from side – mounted sensors (used as control and for shear measurement) to the horizontal booms above?

3.95. In general, is it ensured that not data enters the evaluation where the anemometer is in the wake of the tower?

3.96. Are the horizontal booms long enough to keep the flow distortion below 1%? 3.97. Are there any guy wires upstream of the sensors? Has the impact of this been assessed?

3.98. G.4.2 Tubular meteorological masts Has Figure G.3 been used to choose the booms orientation? Are the horizontal booms facing the

predominant wind direction at 45 degrees?

3.99. Has Figure G.4 been used as guidance for determining the length of the horizontal boom?

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3.100. G.4.3 Lattice meteorological masts Do the horizontal boom orientations face with the main wind direction under an angle of 90

degrees?

3.101. Otherwise has Figure G.6 been used to choose the booms orientation? 3.102. Are the thrust coefficients C_T values been calculated and documented? 3.103. Is the solidity been calculated based on mast data and properly documented?

3.104. Has Equation G.1 and G.2 been used to estimate the centreline wind speed deficit? Has this been used to calculate the minimum boom length need to keep flow distortion from mast below 1%

3.105. G.4 / C.3.2

Side-mounted instruments / Site Calibration


3.106. G.5 Lightning protection Has the lightning finial been installed at least 30 times the finial diameter away from the

anemometers, horizontally?

3.107. Has it been checked if the anemometer is not in the wake of the finial?

3.108. G.5 / C.3.2

Lightning protection / Site Calibration


3.109. G.6 Mounting of other meteorological instruments

Are the wind vanes mounted between 4m and 10 m below the primary anemometer?

3.110. Are the temperature, humidity and pressure sensors located within 10 m of hub height whilst respecting the requirements in G.2 and G.3?

3.111. Has the temperature sensor been mounted in a radiation shield? 3.112. Has the pressure sensor been mounted in a vented water proof box?

3.113.

G.5 / C.3.2

Mounting of other meteorological instruments / Site Calibration


4. Site Calibration Procedure (Clause C / Reported according to 10.j) 4.1. C.1 General In case of REWS definition, is the method applied for each pair of measurement heights used for

the calculation of the REWS?

4.2. C.2 Overview of the procedure As defined and detailed in next items 4.3. C.3 C.3.1.- Test setup: Selection of

test WTG and location of WME - Is the reference mast the same used for power curve measurements?

4.4. - Is the temporary mast located no more than 0.2 H from the centreline of the turbine? 4.5. - Are the reference and wind turbine masts of the same type and have the same boom geometry?

- If not, have the mounting effects been assessed for each of the met masts?

4.6. - Have the recommendations for each of the named as “Type A, B and C“ terrain types followed in the selection of the tested WTG and mast location: “In order to improve the correlation, the reference meteorological mast should be located such that it has a similar elevation and wind conditions as those of the test wind turbine”?

4.7. C.3.2.- Instrumentation Minimum measurements requirements: - Note: Hub height wind speed is covered by item 3.38. - Note: Wind shear is covered by item 3.43. - Wind direction: measured near HH on both met masts? (item 3.50 does not cover this)

4.8. Note: “Does the met masts (both, WTG and reference masts) meet the requirements of 7.2 and Annex G?” is covered under following items :3.20, 3.26, 3.33, 3.38, 3.43, 3.50, 3.71, 3.82, 3.89, 3.105, 3.108, 3.113.

N/A

4.9. - Are the anemometers of each of the two met masts and also those in the different levels at each mast, of the same type, same operation characteristics and calibrated in the same wind tunnel?

4.10. - Are the anemometers used for the power curve measurement of the same type, same operation characteristics and calibrated in the same wind tunnel that the ones used for the site calibration?

4.11. - Only recommended: - Vertical wind speed measurement (within 10% of HH) - Wind veer (wind direction sensor within 10 m of the lower tip height) - Temperature sensor or other ice detection sensor when icing conditions are expected

4.12. Note: the case where the wind direction sensors was removed from SC to PC phases is covered in item 4.33.

N/A

4.13. - Was the reference mast removed and reinstalled between SC and PC? - If so, has it been re-installed in the same conditions (sensors in the same configuration and same boom angles?

4.14. C.4 Data acquisition and rejection criteria

- Have been the data collected at the same sampling rate as for the power curve phase (1 Hz or higher)?

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- Have been the collected continuously? Is this checked and ensured? - Have been the data averaged for 10 min periods derived from contiguous measured data? - Have been mean, standard deviation, minimum and maximum values for each 10 min period derived and stored?

4.15. - Have the data been sorted into 10º with wind direction bins? 4.16. - Is it clearly stated what data sets have been rejected:

- Failure or degradation of test equipment - Wind direction outside the measurement sector - Mean wind speed at wind turbine meteorological mast less than 4 m/s or greater than 16 m/s - Any other special atmospheric conditions that are found to influence the site calibration - Special atmospheric conditions to be used as rejection criteria during the power performance test that are found to influence the site calibration Note: “Have the special atmospheric conditions filtered during the site calibration been filtered during the power curve test also?” is covered under item 5.15.

4.17. C.5 Analysis - Has the general procedure been followed? - Assessment of shear conditions according to C.5.1 - Calculation of flow corrections according to C.5.2 or C.5.3 based on the outcomes of C.5.1 - Additional calculations according to C.5.4 - Note: Uncertainty calculations according to C.6 is covered in items 4.27 onwards. - Quality checks according to C.7

4.18. C.5.1 Assessment of wind shear - Was the wind shear characterised according to C.5.1.1? - 1) scatter plot of wind shear exponent vs. time of day (local time); - 2) scatter plot of wind shear exponent vs. wind direction; - 3) scatter plot of wind shear exponent vs. wind speed; - 4) scatter plot of wind speed vs. time of day (local time) for each of the two met mats and for the filtered database

4.19. - Was the wind shear significance assessed according to C.5.1.2? - Checked whether more than 25% of data have a shear exponent higher than 0.25? - Confirmed by assessment according to C.5.4, specifically: - Self-consistency parameter (eq. C.3) bin averaged against wind speed should be between 0,98 and 1,02 in the range between 4 and 16 m/s within each sector - Linear regression (eq. C.1) should have a R2 > 0,95 within each sector - Dividing the measurement sector to allow for different methodologies for different sectors is permitted.

4.20. - Where there is a requirement to filter on shear at the turbine location: have the wind shear correlations been established according to C.5.1.3?

4.21. C.5.2 Method 1: bins of wind direction and wind shear

- Data sorted into wind direction and wind shear bins? - Wind direction bins of 10º (not less than the wind direction sensor uncertainty) and filtered to the extents of the measurement sector? - Wind shear bins of 0,05 and centred on integer multiples of 0,05? - Direction bin centre definition consistent from the site calibration to the power curve test? - Have the wind speed ratios been averaged for each wind direction and wind shear bins? - Have the completion requirements been reported and fulfilled?

4.22. -Has the level of change of the rations been evaluated against the statistical uncertainty of the site calibration for each wind direction bin? - If the variation of ratio between wind shear bins is higher than twice the statistical uncertainty of the site calibration in any wind direction bins => calculation of flow correction factors according to C.5.2 - If the variation of ratio between wind shear bins is lower than twice the statistical uncertainty of the site calibration in any wind direction bins => calculation of flow correction factors may be done according to C.5.3

4.23. - Has the application of flow correction factors during the power curve test been done according to C.5.2: - Data sorted into wind speed bins - Calculation of wind shear exponent at the reference mast

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- Correction: wind speed ratio interpolated to the measured wind shear value from the wind shear bin average values and the measured wind shear exponent for that wind direction bin. - Extrapolation is permitted for wind shear exponents falling within the last complete wind shear bins. - Interpolation between two complete wind shear bins across an incomplete wind shear bin is permitted - Interpolation between wind direction bins is not permitted

4.24. C.5.3 Method 2: Linear regression method where shear is not a significant influence

- Data sorted into wind direction bins? - Wind direction bins of 10º (not less than the wind direction sensor uncertainty ) and filtered to the extents of the measurement sector? - Direction bin centre definition consistent from the site calibration to the power curve test? - For each wind direction bin: Calculation of the flow correction factors as ordinary least square linear regression with the turbine location wind speed as the dependent variable and the reference wind speed as the independent variable? - Have outliers of the regression been investigated and documented? - Have the completion requirements been reported and fulfilled?

4.25. -Have the following plots been reported for each wind direction bin? - Turbine mast wind speed vs. reference mast wind speed, including an indication of the linear regression and correlation coefficients R2 - Wind speed ratios vs. wind speed as per figure C.11 in clause C.9

4.26. C.5.4 Additional calculations - Have the following calculations been done for each of the results (flow correction factors) calculated according to the methods C.5.2 and C.5.3 above? - Predicted wind turbine location wind speed for each 10-min data point according to eq. C1 - Site calibration residual for each 10-min data point according to eq. C2 - Self-consistency parameter for each 10-min data point according to eq. C3 - Mean and standard deviation for each wind direction bin (used later for the calculation of additional uncertainties in certain scenarios in C.7)

4.27. C.6.1 Site Calibration Category A uncertainty

Has the A uncertainty been calculated using the k-fold cross validation method with k=10 (k ≥ 2 are also permitted)? - Statistical uncertainty for each fold according to eq. C5 and C.6 in clause C.6.1.2 - Total category A uncertainty calculated according to eq. C.4 in clause C.6.1.1 - Only data that have been included in the assessment of the site calibration shall be included in the calculation of the standard deviation - Folds divided by time stamp rather than randomly

4.28. C.6.2 Site Calibration Category B uncertainty

Have the following components been considered? - Anemometer calibration: special considerations to determine the correlations between the anemometers (in WTG and reference met mast and also the anemometer used during the power curve test) when these are calibrated in the same/different wind tunnel and/or are of the same/different model. - Anemometer operational characteristics: special considerations to determine the correlations between the anemometers’ individual uncertainties, that means to what extent the turbine and reference anemometer have been working in that same/different environmental conditions; that applies also to the differences between the site calibration and the power curve test - Mounting effects: the wind turbine meteorological mast anemometer as well as the reference meteorological mast anemometer mounting standard uncertainty shall be taken into account in the site calibration uncertainty evaluation. - Standard uncertainty in wind speed due to the data acquisition (evaluated per Annex D and E)

4.29. C.7 Quality checks and additional uncertainties

Have the following additional checks been performed and reported?

4.30. C.7.1. Convergence check - Has the convergence check been done according to C.7.1 using the self-consistency parameter calculated as per Eq. C.3 and for each wind direction bin? - Has he convergence criteria been met? If not, has any additional measure been taken? - Additional filtering - Self-consistency test according to C.8 (details covered in item 4.35) - Exclusion of wind direction bin

4.31. C.7.2 Correlation check for linear regression

as requested in C.5.3 is covered in items 4.24/4.25. N/A

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4.32. C.7.3 Change in correction between adjacent wind direction bins

- Has the self-consistency parameter calculated as per C.5.4 been used for the evaluation of the change in correction between adjacent wind direction sectors according to C.7.3? - In case the change is more than 2%, has any additional measure been taken? - Rejection of measurement sector - Additional uncertainty as per eq. C.7

4.33. C.7.4 Removal of the wind direction sensor between site calibration and power performance test

- In case of change of the wind direction sensor between the site calibration and the power curve, test, has an additional uncertainty been calculated and applied for each wind direction bin according to eq. C.8?

4.34. C.7.5 Site calibration and power performance measurements in different seasons

- Have the average wind conditions (turbulence intensity, wind shear and upflow) at the reference mast during the site calibration been compared to the ones at the same met mast during the power curve test and for each of the wind directions within the measurement sector? - If those differences differ more than stated in C.7.5, has any additional uncertainty been calculated and applied?

4.35. C.8 Verification of results -Has a self-consistency test been performed and reported (figure C.3) according to C.8? - In case the obtained ratio as per the methodology described there differs significantly from the unity, have those deviations been further analysed and/or rejected? - In case of rejection of wind direction bins, has the power curve been re-evaluated for the remaining sector?

4.36. 10.j Reporting requirements Table including: – minimum and maximum wind direction limits; – the bin-averaged wind direction; – the characteristics of the wind speed correction; – number of hours of data; – combined standard uncertainty of the wind speed ratio for 6 m/s, 10 m/s and 14 m/s;

-Additionally, all those graphs and tables in items above

4.37. Graph including: - Bin-averaged ratio of wind speeds with standard deviation versus wind direction

5. Measurement Procedure and Derived Results (Chapters 5 to 9 / Reported according to 10, References to Annexes A, B, J, I, L.3, R & S) 5.1. 8 Measurement procedure Is the measurement procedure well documented so that it could be reproduced in all procedural

steps given that the data set is available?

5.2. 8.2 Wind turbine operation Has the turbine been in normal operation mode during the test? 5.3. Has the operation mode of the turbine left unaltered? 5.4. Does a test log show that only normal maintenance has been conducted during the test? 5.5. 8.3 Data collection Are the individual samples of raw data stored or are the statistics for each 10 min calculated

and stored?

5.6. In case individual samples are not stored, are the four statistical variables mean value, standard deviation, maximum value and minimum value available for all signals recorded?

5.7. Has the data base been derived from a measurement period of contiguous data? 5.8. Has the sampling rate been of 1 Hz or higher (temperature, pressure and humidity sampling rate

can be lowered up to 1 data per minute)?

5.9. 8.4 Data filtering External conditions described and filtered for? 5.10. Turbine fault condition described and filtered for? 5.11. Maintenance operating mode or manually shut down filtered for? 5.12. Failure or degradation of measurement equipment described, detected and filtered for? 5.13. Wind direction sector filtered for? 5.14. If site calibration has been used: Only completed sectors have been used? 5.15. If site calibration has been used: The same filter conditions for special atmospheric conditions

as in the test have been used.

5.16. Have special subsets of the data base been evaluated and reported? If so, are they clearly distinguished and described?

5.17. Have the data measured under cut-out control algorithm been excluded or, if reported, only in a specific database?

5.18. Have the effects of cut-in control algorithm, as well as the effect of parasitic losses below cut-in, been measured and included in the database (at least cut-in wind speed – 1 m/s)?

5.19. 8.5 Data base Does the data base have at least 180 hrs of accumulated data?

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5.20. Does each bin contain at least 3 samples? 5.21. Has the interpolation option of a single incomplete bin been used? If so, it is well described and

the bin clearly marked?

5.22. Data base completeness The report shall state which of the three completeness criteria has been used a) Range from 1 m/s below cut in wind speed to P(85% v_rated) x 1.5 or b) AEP measured / AEP extrapolated > 0.95 or c) variation between bins of P_net in rated power range below 0.5% or 5 kW (the larger) for at least three consecutive bins (and no increasing trend is observed).

5.23. 9 Derived results Is there a description which of the steps in Figure 4 have been applied to the data base? The minimum required steps for a hub height power curve are: “Raw 10 minute data”, “Site calibration” (if applicable), “Air density correction” -> “Normalized data base”

5.24. 9.1.2 Side mounted anemometers In case side mounted anemometers at hub height are used: Has the data been corrected according to annex S? Is the implication for the mounting uncertainty in any case documented? Is the flow distortion by the tower in the sector below 1%?

5.25. 9.1.3.2 9.1.3.4

Rotor equivalent wind speed If a REWS has been calculated, has it been done according to Equations 5 or 11. To be assessed through a LPT

5.26. 9.1.3.3 Wind shear correction factor If the wind shear correction factor is reported, has it been obtained according to equations 9 (case 1) or 10 (case 2) and is it reported

5.27. 9.1.4 Wind veer correction In case the REWS includes the variation of wind direction over the rotor height range, has been calculated according to Annex Q (informative); if other method, is it described?

5.28. 9.1.5 Air density normalization Has the equation 12 been used for the calculation of the air density? 5.29. Has the correct formula (Formula 13 or formula 14) for the normalization been selected

depending on turbine control?

5.30. Is it reported the reference air density for the reported power curve (average during the measurement period rounded to the nearest 0,01 kg/m3 or predefined nominal air density for the period)?

5.31. 9.1.6 Turbulence normalization Has turbulence normalization been applied for the reported power curve? (The calculation is required in any case for the uncertainty 6.14/6.70, the reporting is optional)

5.32. Is the reference turbulence intensity or turbulence intensity distribution mentioned? 5.33. Has the turbulence normalization been made according to Annex M; if other method, is it

described,

5.34. 9.2 Determination of the measured power curve

Has the method of bins been applied using formulas 15 and 16? 5.35. Is it at least the power curve based on hub height wind speed reported?

If measured, is it reported the REWS power curve?

5.36. 9.3 AEP calculation Does the report state clearly if the AEP is referring to the HH or REWS wind speed definition? 5.37. Does the report state clearly if “generic AEP” or a “site specific AEP “ has been calculated? If

so, are the parameters of the wind speed distribution listed?

5.38. Has the summation been set to 0 kW for the lowest unfilled bin? 5.39. Is the ratio AEP measured / AEP extrapolated reported together with the associated

uncertainties?

5.40. 9.4 Cp value Has the cp value been calculated with the correct assumed reference air density? 5.41. 9.4 and

definition 3.26

Has the rotor swept area taken into account following the definition 3.26? (The plane normal to axis of rotation may not be in line with the horizontal wind)

5.42. 10 d 1) and clause 8

Measurement procedure description

Documentation of procedural steps available?

5.43. 10 d 2) and clause 8

Sufficiently maintained logbook available?

5.44. 10 d 3) and clause 8

A complete list of all filter criteria available and discussed?

5.45. 10 e 1) Presentation of the measured data base

Plot: Power signal scatter plots (min/ max, sigma and P) over normalized wind speed 5.46. 10 e 2) Plot: Mean wind speed and turbulence over wind direction 5.47. 10 e 3) Plot: Turbulence intensity over wind speed (scatter plot), the same binned over wind speed 5.48. 10 e 4) Any special data bases to be presented as 10 e 1) to 10 e 3)

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5.49. 10 e 5) Plot and Table: If measured: RPM and Pitch angle over wind speed together with tabulated info presented?

5.50. 10 e 6) Plot: Status signal definition and plots of the filtered data base over power available? 5.51. 10 e 7) Plot: Air density over wind direction and wind speed available? 5.52. 10 e 8) Plot: Wind shear exponent over time of day and over wind speed available. Separate

presentation for shear in the lower and the upper rotor half available? In addition, average values of the two shear exponents to be shown.

5.53. 10 e 9) Number: Average shear exponent of the data base presented (HM: Include Min / Max) 5.54. 10 e 11) Number: Present the average shear correction factor during the test. 5.55. 10 f 1) Presentation of measured

power curve (here HH only) Table available listing for each bin normalized wind speed, normalized power, data set count, derived cp value, type A uncertainties, type B uncertainties, combined uncertainties?

5.56. 10 f 2) Graph of the power curve similar to Fig. 6 available? 5.57. 10 f 3) Graph of the cp curve similar to Fig. 6 available? 5.58. 10 f 4) Plots and Graphs are stating the assumed reference air density 5.59. In case cut out behaviour has been observed, has a special data base been presented following

10 f 1) to 10 f 4) points?

5.60. 10 g) Special operational conditions reported

In case this is observed: Has the reporting been followed up in a similar and complete way?

5.61. 10 h 2) Estimated AEP (here HH only) Table with AEP measured, Standard uncertainty of AEP measured and AEP extrapolated has been made available? Table shall carry information of reference air density and assumed cut out wind speed.

5.62. 10 h 3) Completeness Completeness of the power curve with regards to the 95% criteria to be listed (HM – to be fair: and discussed with regards to the other two criteria also allowed in this standard)

5.63. 10 i) and 10 f 3)

Cp curve Table and graph shall be available

6. Evaluation of uncertainty in measurement (Clause D and E / Reported according to 10.k) NOTE: Requirements referred only in Annex E of the standard are to be considered only as “Informative”. Requirements referred in the main core of the standard, Annex D and Annex K are to be considered as “mandatory”

6.1. D.1 Uncertainty categories Is the power curve supplemented with an estimate of uncertainty according to the ISO/IEC Guide 98-3:2008 ?

6.2. Are uncertainties split into category A and B according to ISO/IEC Guide 98-3:2008 ? 6.3. Are uncertainties expressed as standard deviations? 6.4. Electric Power Table including uncertainties for:

- Current transformers B - Voltage transformers B - Power transducer or power measurement device B - Data acquisition system (see 6.11) B - Variability of electric power A

6.5. Wind speed (cup and sonic anemometer)

Table including uncertainties for: - Anemometer calibration B - Classification B - Mast flow distortion B - Boom flow distortion B - Lightning final B - Data acquisition system (see 6.11) B - Post calibration / in-situ test B

6.6. Rotor equivalent wind speed Table including uncertainties for: - Wind shear measurement B - Wind veer measurement B

6.7. Wind direction (vane or sonic) Table including uncertainties for: - Calibration B - North mark B - Boom orientation B - Operation (influence of mast) B - Magnetic declination angle B - Data acquisition system (see 6.11) B

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6.8. Air temperature Table including uncertainties for: - Temperature Sensor B - Radiation shielding B - Mounting effects B - Data acquisition system (see 6.11) B

6.9. Air pressure Table including uncertainties for: - Pressure Sensor B - Mounting effects B - Data acquisition system (see 6.11) B

6.10. Relative humidity Table including uncertainties for: - Humidity sensors B - Mounting effects B - Data acquisition system (see 6.11) B

6.11. Data acquisition System Table including uncertainties for: - Signal transmission - System accuracy - Signal conditioning

6.12. Terrain (no site calibration) Table including uncertainties for: - Flow distortion due to terrain B (details checked in item 6.49)

6.13. Terrain (with site calibration) Table including uncertainties for: - Anemometer calibration before test B (details checked in item 4.28) - Post calibration/In-situ calibration B (details checked in items 4.28 and 6.33 to 6.43) - Anemometer classification B (details checked in item 4.28) - Mounting effects B (details checked in item 4.28)

o Standard mounting B o Alternative mounting B o Side mounted B

- Lightning finial B - Data acquisition system (see 6.11) B - Change of correction (adjacent wind direction bins): item 4.32. - Removal of wind direction sensor between site calibration and power cure measurement

B (details checked in item 4.33) - Seasonal variation B (details checked in item 4.34) - Statistical variability in site calibration A (details checked in item 4.27)

6.14. Method Table including uncertainties for: - Air density correction B - Wind conditions – missing shear information B - Wind conditions – missing veer information B - Wind conditions – missing upflow information B - Wind conditions – missing turbulence information B - Seasonal effects B - Turbulence normalisation (or lack of turbulence normalisation) B - Cold climate measurements B

6.15. E.2.1 Combining uncertainties Are the combined standard uncertainty components calculated according to the method given in Formula E.1, E.2. ?

6.16. Which of the following assumptions are made for uncertainty calculation? • Are uncertainty components fully correlated or independent • Category A uncertainties uncorrelated across wind speed bins; Category B uncertainties

fully correlated across wind speed bins • For site calibration uncertainties: Category A uncertainties uncorrelated across wind

direction bins, Category B uncertainties fully correlated across wind direction bins

6.17. Is the correlation of the same type of uncertainty across different measurement heights assessed individually for each component and each case?

6.18. Are components of category A, which cannot be derived on a bin wise basis added quadratically into AEP uncertainty?

6.19. E.2.2 Expanded uncertainties Are uncertainties expanded by a coverage factor as shown in the Table E.1?

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6.20. E.2.3 Basis for the uncertainty assessment

Are sensitivity factors and magnitude listed according to the Table E.2 and analog to the List in part D.1.?

6.21. Are the ranges for the uncertainty components considered? Are uncertainty values not estimated with a value of zero?

6.22. Note: “Is the wind direction uncertainty reported?” is covered under item 6.72. N/A 6.23. Are uncertainties converted to a coverage factor consistent with all uncertainty inputs? 6.24. E.3 Category A uncertainties Are category A uncertainties considered? 6.25. E.4 Category B uncertainties: Data

acquisition system Is the standard deviation calculated if uncertainties are expressed as uncertainty limits or have non-unity coverage factors?

6.26. Is the data acquisition uncertainty estimated for a specific test setup including the contributions to the data acquisition uncertainty mentioned in E.4.2?

6.27. Is an assessment of the actual uncertainty of the data acquisition system done to ensure that the uncertainty of the data acquisition system is negligible?

6.28. E.5 Category B uncertainties: Power output

Is the uncertainty related to the data acquisition system added to the power signal?

6.29. E.5.2 Category B uncertainties: Power output – Current transformers

Are additional uncertainties added if current transformers are not operated within their secondary loop operational limits?

6.30. E.5.3 Category B uncertainties: Power output – Voltage transformers

Are voltage transformers used? Are uncertainty components set to zero if not used? 6.31. Are additional uncertainties added if voltage transformers are not operated within their secondary

loop operational limits?

6.32. E.6.3.2 Category B uncertainties: Wind speed – Met mast sensors – Pre-calibration

Are the values as indicated on the calibration for the employed sensors used for uncertainty calculation?

6.33. E.6.3.3 / 7.2.2

Category B uncertainties: Wind speed – Met mast sensors – Post-calibration

Amongst post-calibration and in-situ comparison, was at least one of the two method used? (For each anemometer used in the results of the test.)

6.34. E.6.3.3 / 7.2.2

If an in-situ and post-calibration has been carried out, is the uncertainty component taken from post-calibration?

6.35. E.6.3.3 / 7.2.2

Post calibration: Has the difference between regression lines of calibration and post calibration been assessed?

6.36. E.6.3.3 / 7.2.2

Post calibration: if the difference between pre and post calibration is greater than 0.1 m/s in the range 4 to 12 m/s, has u_VS,postcal been taken at least as the maximum of that difference in that range? Note: Annex E omits the 0.1 m/s limit, but is not normative.

6.37. 7.2.2 Post calibration: if the difference between pre and post calibration is greater than 0.2 m/s in the range 4 to 12 m/s,

- has the in-situ comparison been used to identify the point in time when the deviation occurred, and has the subsequent data been rejected?

- When that was not possible, has u_VS,postcal been taken at least as the maximum difference?

6.38. K.3 In-situ comparison: Wind speed range: does it cover the range from 4 to 12 m/s? 6.39. K.3 In-situ comparison: measurement sector:

- is it included in the valid measurement sector? - Does it meet the requirements of K.3.d

6.40. K.3 In-situ comparison: binning: - Do all bins at least have 3 samples in them? - Is the selected binning method (Option 1 / Option 2) stated?

6.41. K.3 In-situ comparison: duration: - Is the maximum duration of each database <= 8 weeks? - In case the measurement period is a shorter than 16 weeks both databases do not

overlap?

6.42. E.6.3.3 / K.4

In-situ comparison: if the maximum value for δ is between 0.1 and 0.2 m/s, has u_VS,postcal been taken at least as this value? Note: Annex E omits the 0.1 m/s limit, but is not normative.

6.43. E.6.3.3 / K.4

In-situ comparison: if the maximum value for δ is found greater than 0.2 m/s, was the whole measurement period for the test reduced so that this threshold is not reached?

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6.44. E.6.3.4 Category B uncertainties: Wind speed – Met mast sensors – Classification

Does the sensor classification (Class A,B or S) used match with the terrain type? Is a reference to the classification report included? Note: this is NOT the same requirement as in items 3.15/3.16: the formers address whether the sensor complies or not, this one addresses whether the class number used is the correct one.

6.45. If upflow is not measured, can it be argued from the terrain slopes in accordance to the IEC 61400-1:2005

6.46. E.6.3.5 Category B uncertainties: Wind speed – Met mast sensors – Mounting

Is uVS,mnt,i consistent with the type of mounting arrangement?

6.47. E.6.3.6 Category B uncertainties: Wind speed – Met mast sensors – Lightning finial

If a lightning finial is present, is the corresponding uncertainty consistent?

6.48. E.6.3.7 Category B uncertainties: Wind speed – Met mast sensors – Data acquisition

Covered by items 6.11 and 6.25 onwards.

6.49. E.9.1 / 6.3.4

Category B uncertainties: Wind speed – Terrain – General

In case no site calibration is performed (items 2.6 & 6.12 lead to here): Does the uncertainty due to flow distortion meet the minimum values from 6.3.4? Note: values proposed for offshore in this informative annex ARE deviations from the standard, and therefore must be identified accordingly.

6.50. E.9.1 / 6.3.4

Category B uncertainties: Wind speed – Terrain – General

In case a site calibration is performed (item 6.13 leads to here): Covered by:

- Items below until 6.57, - Items 6.13 + 4.30 + 4.24 + 4.25

6.51. E.9.2 Category B uncertainties: Wind speed – Terrain – Pre-calibration

Covered under item 4.28.

6.52. E.9.3 Category B uncertainties: Wind speed – Terrain – Post-calibration

Refer to items 6.33 to 6.43.

6.53. E.9.4 Category B uncertainties: Wind speed – Terrain - Classification

Is the magnitude of the uncertainty taken from the classification report? Special care has to be taken that the terrain sensor matches the terrain type of the classification of the sensor.

6.54. Is a reference to the classification report included in the site calibration report? If no reference is included the default magnitude for the uncertainty is a class 3,4A taken for non-complex or a class 4,5B taken for complex terrain?

6.55. Is the measured range of the influence parameters reported for the same data set used for the site calibration report? If upflow is not measured, is this argued by the terrain slopes?

6.56. E.9.7 Category B uncertainties: Wind speed – Terrain – Data acquisition

Are the data acquisition uncertainty counted twice?

6.57. E.9.10 Category B uncertainties: Wind speed – Terrain – Seasonal variation

Is this uncertainty only applied if conditions for a wind direction bin differs between site calibration and power performance test by more than the following amounts?

• 0,05 for wind shear exponent • 3 % for turbulence intensity • If upflow is measured, a limit of 2°−

+ change in vertical upflow is recommended

6.58. E.10.11 Category B uncertainties: Air density – Relative humidity introduction

If relative humidity is not measured, is a default value of 50% with an uncertainty of 100% assumed?

6.59. E.10.15 Category B uncertainties: Air density - Correction

Are uncertainties for a stall-regulated wind turbine with constant pitch and constant rotational speed evaluated by bin averaging the air density normalized power output and the measured power output against the wind speed at hub height?

6.60. Are the uncertainties for active power control wind turbines evaluated by bin averaging the measured wind speed against the wind speed normalised for the air density?

6.61. E.11.2.2.2 Category B uncertainties: Method – Wind conditions – Shear – half rotor coverage

Is the uncertainty of the measured power curve due to wind shear conservatively estimated and taken into account even if no wind shear measurement is performed? Has a wind shear correction factor been calculated assuming following assumptions?

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• 20 virtual wind speed measurements equally distributed over the rotor height with weighting factors

• Assume one power law for lower rotor half and another for upper rotor half. Wind shear exponent for lower half should be calculated from measurements for each 10min data

6.62. E.11.2.2.2 Category B uncertainties: Method – Wind conditions – Shear – no measurement

If no wind shear was measured, is the standard uncertainty of the measured power curve calculated by formula E.30?

6.63. E.11.2.2.3 Category B uncertainties: Method – Wind conditions – Shear – full rotor coverage

Uncertainty estimated by fitting a power law through each pair of wind speed measurements of successive measurement heights? Wind speed according to this power law calculated for at least 10 height levels equally distributed between each pair of measurement heights?

6.64. E. 11.2.3.2

No veer measurement Is a wind veer factor calculated based on the following assumptions? • Assuming wind speeds to be equal to 1 at all measurement heights. Then Equation (Q.1)

transforms to a wind veer correction factor. • Assuming 20 virtual wind direction measurements equally distributed over the rotor height

range, resulting in 20 weighting factors • Assuming homogeneous wind veer over the entire rotor height range as large as can be

reasonably expected for the test site. If no reasonable assumptions about extreme wind veer are possible for the test site, a wind veer of 40°/100 m shall be assumed

6.65. E. 11.2.3.3

Half rotor veer measurement Is the uncertainty related to a veer measurement across half a rotor estimated using the same procedure as used for the veer across a full rotor, with the change that the wind veer across the full rotor is 2,5 times that measured across the half rotor?

6.66. E.11.2.3.4 Full rotor veer measurement Is the uncertainty estimated by assuming a linear increase of the wind veer between each pair of wind speed measurements of successive measurement heights? Is the wind speed calculated for at least 10 height levels equally distributed between each pair of measurement heights? Is the percentage deviation of the resulting rotor equivalent wind speed to the rotor equivalent wind speed using only the measured wind directions assumed as standard uncertainty of the wind speed due to the limited number of wind direction measurement heights?

6.67. E.11.2.4 Category B uncertainties: Method – Wind conditions – Upflow

Are the uncertainties applied for sites that do not meet the requirements of Annex B?

6.68. E.11.2.4 Category B uncertainties: Method – Wind conditions – Turbulence Intensity

If the hub-height turbulence is not measured directly by a mast-mounted anemometer, was uM,ti,i introduced accordingly?

6.69. E.11.3 Category B uncertainties: Method – Wind conditions – Seasonal effect

Is uM,sfx,i present and its magnitude justified?

6.70. E.11.4 Category B uncertainties: Method – Wind conditions – Turbulence Normalisation

Is uM,tinorm,i present and its magnitude justified?

6.71. E.11.5 Category B uncertainties: Method – Cold Climate

Is the uncertainty component for the sensor classification based on a class S report if an extended temperature range is required?

6.72. E.12.1 Category B uncertainties: Wind direction

Wind direction uncertainty is reported and stays below 5 degrees. Note: whether it encompasses all applicable uncertainty components from Clause E.12 as a minimum: covered in items 6.7/6.73.

6.73. E.12.2.1 Category B uncertainties: Wind direction – Vane or sonic

Is the resolution of the wind direction sensor included in the calibration uncertainty? Note: all other requirements from E.12.2 are covered in item 6.7.

6.74. E.13.10 Combining uncertainties in the wind speed measurement from REWS due to wind veer across the whole rotor 𝑢𝑢𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅,𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣

Are the relative wind directions 𝜙𝜙𝑚𝑚,𝑖𝑖 and wind speeds 𝑣𝑣𝑚𝑚,𝑖𝑖 measured at the different measurement heights bin averaged as function of the wind speed?

6.75. Are the correlation coefficients suggested in Table E.8 applied for the calculation of the uncertainties?

6.76. Are lower correlation coefficients used only if they are evident and relevant data is reported? 6.77. E.13.11 Combining uncertainties in the

wind speed measurement from flow distortion to site calibration 𝑢𝑢𝑉𝑉𝑉𝑉,𝑖𝑖

Is the weighted average according to Formula E.53 used to obtain the uncertainty in one wind speed bin across all the directional sectors?

– 20 – IECRE OD-551-24:2020 © IEC 2020

Item no





7. Application of remote sensing technology (Clause L) 7.1. L.1 / L.2 Classification of remote sensing

devices Has the RSD been classified before the power curve test according to clause L.2 (minimum of two instruments of each type and at a minimum of two locations)?

7.2. L.1 / L.3 Verification of the performance of remote sensing devices

Has the RSD been verified or calibrated according to clause L.3 either prior to the start of the power curve tests (not earlier than one year prior to the start of the power curve test) or during the power curve test?

7.3. L.1 / L.4 Evaluation of uncertainty of measurements of remote sensing devices

Has the uncertainty related to the RSD measurements been calculated according to clause L.4, including the different components defined from L.4.1 to L.4.7?

7.4. L.1 / L.5 Additional checks Have the additional checks defined in clause L.5 (from L.5.1 to L.5.4) been performed? 7.5. L.1 / L.6 Other requirements specific to

power curve testing Have the additional requirements in clause L.6 been considered?

7.6. L.1 / L.7 Reporting Have been the requirements in clause L.7 reported according to: - L.7.1 Common reporting on classification test, calibration test, and monitoring of the

remote sensing device during application - L.7.2 Additional reporting on classification test - L.7.3 Additional reporting on calibration test - L.7.4 Additional reporting on application

8. Small Wind Turbine Power Curve test (Clause H) 8.1. H All requirements described in

this standard shall be met with the following additions and changes

Additionally, to all the requirements previously stated, it must be checked the compliance of exceptions in Clause H a) to r)

9. Deviations from the procedure (Reported according to 10.l) 9.1. 10.l) Reporting on deviations It must be checked that any deviations from the requirements of this standard is clearly

documented in a separate clause. Each deviation has to be supported with the technical rationale and an estimate of its effect on test results. Those items identified in this checklist as “non-compliance” which are clearly reported and rationally supported in this clause will not be considered as “non-compliance”

4 (*) Minor and major finding are defined as: 5 6

- Minor: does not affect final results 7 - Major: could affect final results 8 - Depending on details, minor/major can be tweaked during the assessment9

INTERNATIONAL IEC SYSTEM FOR CERTIFICATION TO STANDARDS ELECTROTECHNICAL RELATING TO EQUIPMENT FOR USE IN RENEWABLE COMMISSION ENERGY APPLICATIONS (IECRE SYSTEM) IECRE Secretariat c/o IEC 3, rue de Varembé 3, rue de Varembé PO Box 131 PO Box 131 CH-1211 Geneva 20 CH-1211 Geneva 20 Switzerland Switzerland Tel: + 41 22 919 02 11 Tel: + 41 22 919 02 11 [email protected] [email protected] www.iec.ch www.iecre.org

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