HOUTEN WIND FARM WIND RESOURCE ASSESSMENT

Transcription

1 CIRCE CIRCE Building Campus Río Ebro University de Zaragoza Mariano Esquillor Gómez, Zaragoza Tel.: Fax: HOUTEN WIND FARM WIND RESOURCE ASSESSMENT CIRCE AIRE Area ENECO NL 06/05/2014

2 DOCUMENT IDENTIFICATION Houten WF Wind Resource Assessment CUSTOMER ENECO NL SITE Netherlands (NL) REFERENCE _WRA_Houten_WF Version Date Reason 1 06/05/2014 Initial version FUNDACIÓN CIRCE CIRCE Building C/ Mariano Esquillor Gómez, Zaragoza (España) Tlf.: Fax: Carried out by Revised by Approved by L. F. Lozano E. Telmo E. Telmo This report may not be partially reproduced, except with the prior written permission of the issuing company. In no circumstances may CIRCE be held responsible for the accuracy of the information supplied by the customer. Page 2 of 63

3 INDEX 1. INTRODUCTION Objective Input data WIND DATA ANALYSIS Meteorological masts Monthly average wind speed Measure-Correlate-Predict method (MCP) DEFINITION AND SELECTION OF THE REFERENCE PERIOD Selection of the reference period Long-term study Analysis of the reference period Wind shear AIR DENSITY ENERGY YIELD CALCULATION Input data of WAsP model Wind Turbine Power Curves WAsP model correction requirements WAsP model results UNCERTAINTY STUDY CONCLUSIONS APPENDIX I: WIND DATA ANALYSIS AND TREATMENT APPENDIX II: WIND DATA STATISTICS. REFERENCE PERIOD APPENDIX III: NOISE CURTAILMENTS LOSSES STUDY APPENDIX IV: SHADOW FLICKER LOSSES STUDY APPENDIX V: ILLUSTRATIONS Page 3 of 63

4 1. INTRODUCTION 1.1. Objective The aim of this document is to present the results obtained in the wind resource and energy yield assessment study for Houten Wind Farm located in Netherlands (NL). The following figure shows the location of the studied site. Figure 1. Location of Houten Wind Farm. Houten Wind Farm presents a layout of 3 wind turbines, which has been provided by the customer. The wind turbine model considered in this study is Vestas V MW at 105 m hub height. Page 4 of 63

5 1.2. Input data The data necessary to carry out the wind energy assessment have been provided by the customer. These data are described below: Wind data collected from two meteorological masts located in the site. Houten Wind Farm layout. Nieuwegein Wind Farm layout (neighbouring wind farm). Power curves of the studied wind turbine models. Besides the data provided by the customer, the following data have been obtained by CIRCE: Virtual wind data (MERRA) for the long-term analysis. Digital maps of the site (downloaded from Global Mapper software). In the present study, the coordinates of the meteorological masts and the Wind Farm layouts will be shown in RD (Rijks-Driehoek) coordinates system. The following figure shows the map of Houten Wind Farm site in which the contour lines, the neighbouring Nieuwegein Wind Farm and the considered meteorological masts are represented. Figure 2. Meteorological masts located at Houten and Nieuwegein wind farms. Contour lines every 5 m. Page 5 of 63

6 2. WIND DATA ANALYSIS Before doing any kind of wind resource and energy yield assessment, it is essential to analyse the data measured in the meteorological masts in order to guarantee their quality Meteorological masts The customer has provided the wind data corresponding to two meteorological masts, Houten and Nieuwegein, located in the site. Both met masts have been set up to record information regarding average wind speed and average wind direction every ten minutes, and in the case of Nieuwegein met mast, standard deviation of wind speed and temperature. The coordinates (RD, Rijks-Driehoek), measurement levels and available period of measurement of each meteorological mast can be seen in the following table. Meteorological Mast Coordinates (RD, Rijks-Driehoek) X (m) Y (m) Measurement Height (m) Measurement Period Nieuwegein /68.5/58.6/30 12/09/ /03/2014 Houten /10/ /02/2014 Table 1. Coordinates, measurement levels and measurement period for each meteorological mast Monthly average wind speed Taking into account the original filtered data 2, the monthly average wind speed values have been obtained for each measurement level of the available meteorological masts. These tables are shown in APPENDIX I: Wind data analysis and treatment. The temporal evolution of the monthly average wind speed at the measurement levels of each meteorological mast is shown in the figure below. It has only been considered months with a high availability of filtered data (percentage higher than 90 %). 1 Houten met mast coordinates has not been provided by the customer. Therefore, CIRCE has obtained these coordinates taking into account the indications and site s pictures provided by the customer. 2 The expression original filtered data refers to the data considered as valid after statistic filtering process and before regenerating process. Page 6 of 63

7 Average Wind Speed (m/s) Nieuwegein 70 m Nieuwegein 58.6 m Houten 10 m Nieuwegein 68.5 m Nieuwegein 30 m Data (MMYY) Figure 3. Temporal evolution of monthly average wind speed for each measurement level in Nieuwegein and Houten met masts Measure-Correlate-Predict method (MCP) Due to the low period of measurement data in Nieuwegein (around 6 months) and Houten (around 4 months) met masts and the necessity of data availability during at least a whole year at all met masts in order to carry out a proper wind resource assessment, it is necessary to fill the data in order to complete one whole year in wind speed and wind direction series. In this sense, ten-minute correlation analyses among Nieuwegein and Houten met masts and a nearby reference met station, with a long period of measured data, have been carried out in order to complete the upper level measured in Houten and Nieuwegein met masts during one whole year Wind data correlation among measurement heights For any of the considered met masts, no regeneration among measurement levels (of the same mast) was applied since it does not increase the availability of the upper level. Page 7 of 63

8 Wind data correlation among different measurement masts To perform this regeneration process, MCP method has been used among a nearby reference met station and Nieuwegein and Houten met masts upper measurement levels. The obtained results are shown in Tables 2 and 3. The period of data taking into account for the correlation between each met mast and the reference met station is from 12/09/2013 to 28/02/2014 in the case of Nieuwegein met mast and from 23/10/2013 to 28/02/2014 in the case of Houten met mast. Nieuw egein 70 m vs Reference station 80 m Sector Equation R 2 Data N V(NIEU)= V(Ref.S.) NNE V(NIEU)= V(Ref.S.) ENE V(NIEU)= V(Ref.S.) E V(NIEU)= V(Ref.S.) ESE V(NIEU)= V(Ref.S.) SSE V(NIEU)=0.738 V(Ref.S.) S V(NIEU)= V(Ref.S.) SSW V(NIEU)= V(Ref.S.) WSW V(NIEU)= V(Ref.S.) W V(NIEU)= V(Ref.S.) WNW V(NIEU)= V(Ref.S.) NNW V(NIEU)= V(Ref.S.) GLOBAL V(NIEU)=0.736 V(Ref.S.) Table 2. Correlation equations and coefficients considering Nieuwegein met mast (70 m) and the reference met station (80 m). Houten 10 m vs Reference station 20 m Sector Equation R 2 Data N V(HOU)= V(Ref.S.) NNE V(HOU)= V(Ref.S.) ENE V(HOU)= V(Ref.S.) E V(HOU)= V(Ref.S.) ESE V(HOU)= V(Ref.S.) SSE V(HOU)= V(Ref.S.) S V(HOU)= V(Ref.S.) SSW V(HOU)= V(Ref.S.) WSW V(HOU)= V(Ref.S.) W V(HOU)= V(Ref.S.) WNW V(HOU)= V(Ref.S.) NNW V(HOU)= V(Ref.S.) GLOBAL V(HOU)= V(Ref.S.) Table 3. Correlation equations and coefficients considering Houten met mast (10 m) and the reference met station (20 m). Page 8 of 63

9 Considering the previous results, Tables 4 and 5 show monthly wind speed values and the number of regenerated data in Nieuwegein and Houten met masts during a whole year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m_regenerated Data % 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Reg. data % 100% 100% 100% 100% 100% 100% 39% 0% 0% 0% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m_regenerated Data % 100% 100% 40% Reg. data % 3% 4% 0% Accumulated W.S. Nieuwegein m_regenerated Data % 95% Reg. data % 52% Table 4. Monthly wind speed, accumulated wind speed and data regenerated at 70 m in Nieuwegein meteorological mast Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m regenerated Data % 100% 100% 100% 94% 100% 100% 100% 100% 100% 100% Reg. data % 100% 100% 100% 100% 100% 100% 100% 73% 1% 0% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m regenerated Data % 100% 100% Reg. data % 0% 0% Accumulated W.S. Houten m regenerated Data % 99% Reg. data % 65% Table 5. Monthly wind speed, accumulated wind speed and data regenerated at 10 m in Houten meteorological mast. Due to the large number of regenerated data in Nieuwegein and Houten met masts, the results obtained with these meteorological masts must be taken with caution. This has been considered in the uncertainty study. Page 9 of 63

10 3. DEFINITION AND SELECTION OF THE REFERENCE PERIOD One of the major characteristics of the wind is its annual, seasonal and daily variability, meaning that its average speed and energy yield can differ from one year to another. In general terms, the wind resource assessment at a prospective site requires a measured period of as many years as possible to reflect the seasonal variations of the wind Selection of the reference period After analyzing the representativeness of each meteorological mast and considering the availability of the recorded and regenerated data, a common reference period for Nieuwegein and Houten met masts has been selected. In the following table average wind speed, number of data and availability, together with the accumulated average wind speed value for the possible reference periods of each met mast are shown. 313/ /314 A.W.S. Nieuwegein m regenerated Data % 100% 95% Houten m regenerated Data % 99% 91% Table 6. Possible reference periods and accumulated average wind speed during the complete measurement period at Nieuwegein and Houten met masts. The reference period considered in both meteorological masts is: - March 2013 to February A common period, 1 year, has been considered in order to obtain a representative interval. Only one year has been considered due to the short measurement period in order to include as much original data as possible. The average wind speed, number of data and availability, as well as accumulated average wind speed during the reference period at the upper measurement level of Nieuwegein and Houten met masts are shown in the table below. Page 10 of 63

11 Met station Nieuwegein m_regenerated Data % 100% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Houten m_regenerated Data % 100% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Accumulated W.S. Nieuwegein m_regenerated Data % 100% Houten m_regenerated Data % 100% Table 7. Monthly average wind speed, accumulated average wind speed and number of data in the reference period in each meteorological mast. Due to its representativeness (considering its location and measurement levels), Nieuwegein met mast (70 m) will be taken into account for the wind resource model, while Houten met mast (10 m) has been used to check the WAsP model extrapolation results and to obtain the noise regulation losses estimate Long-term study For an assessment in depth of the wind resource of an area, a wind data series of several years would be necessary. However in most cases this long series is not available. For this purpose a so-called long-term correlation among the data gained from the measurement campaign at the site (met masts) and appropriate long-term stations (reference data) should be carried out. To perform the long-term study for Houten Wind Farm, the following long-term data were available: - 1 reference meteorological station located near the site during the period January 2001 February MERRA nodes during the period January 1984 February The considered nodes data have been obtained by CIRCE through WindPRO Reference meteorological station. 13 years of data from the reference meteorological station at 80 m of height have been used. The following table shows the long-term wind speed value and the distance to the meteorological mast (Nieuwegein) considered in the study. LT Reference WS LT (m/s) Distance (km) Nieuwegein Ref_Station Table 8. Long-term wind speed in the reference met station and distance to the Nieuwegein meteorological mast. The reference met station is located 14 km in the southwest direction of Houten Wind Farm. Page 11 of 63

12 The following figure shows the location of the reference met station and the Houten Wind Farm site. Figure 4. Location of the reference met station and Houten Wind Farm site. The daily average wind speed values at Nieuwegein met mast and at the reference met station follow a similar trend. In order to check if the chosen reference period is representative of long term behaviour at the site, linear correlations among daily average wind speeds of Nieuwegein met mast and reference met station data have been calculated. Only days with high data availability (90% and above) have been considered. The applied method to create the relationship among Nieuwegein meteorological mast and reference met station data is a linear regression between the site and the reference wind speed values. This results in an equation of the form y = a x + b, where x is the reference wind speed and y the expected wind speed at the site. In the following table the daily correlation coefficient and equation obtained among Nieuwegein met mast and the reference met station are shown. Met Mast LT Reference Correlation equation R 2 Data (days) Nieuwegein Ref_Station V(Nieuwegein) = V(Ref_Station) Table 9. Correlation equation and coefficient among Nieuwegein met mast and the reference met station. Page 12 of 63

13 According to the obtained results, where a high correlation coefficient between Nieuwegein met mast and the reference met station has been obtained, the long term wind speed value estimation for Nieuwegein met mast was calculated. The table below shows the average wind speed for the selected reference period, the long-term wind speed value estimated using the reference met station and the discrepancy of the wind speed values. Met Mast WS LT (m/s) WS Ref. P. (m/s) Discrepancy (%) Nieuwegein Table 10. Long-term wind speed, reference period wind speed and discrepancy MERRA nodes data. 30 years of data from 4 MERRA nodes at 50 m of height have been used. The following table shows the MERRA nodes coordinates, the long-term wind speed values and the distance to the meteorological mast (Nieuwegein) considered in the study. LT Reference Latitude (º) Longitude (º) WS LT (m/s) Distance (km) Nieuwegein N1_MERRA N2_MERRA N3_MERRA N4_MERRA Table 11. Coordinates, long-term wind speed values in MERRA nodes and distances to the Nieuwegein meteorological mast. The following figure shows the location of the 4 MERRA nodes and the Houten Wind Farm site. Page 13 of 63

14 Figure 5. Location of the 4 MERRA nodes and Houten Wind Farm site. The daily average wind speed values at Nieuwegein met mast and at the nodes follow a similar trend. In order to check if the chosen reference period is representative of long term behaviour at the site, linear correlations among daily average wind speeds of Nieuwegein met mast and MERRA nodes reference data have been calculated. Only days with high data availability (90% and above) have been considered. The applied method to create the relationship among Nieuwegein meteorological mast and MERRA reference data is a linear regression between the site and the reference wind speed values. This results in an equation of the form y = a x + b, where x is the reference wind speed and y the expected wind speed at the site. In the following table the daily correlation coefficients and equations obtained among Nieuwegein met mast and the four long-term reference nodes are shown. Met Mast LT Reference Correlation equation R 2 Data (days) Nieuwegein N1_MERRA V(Nieuwegein) = V(N1_MERRA) N2_MERRA V(Nieuwegein) = V(N2_MERRA) N3_MERRA V(Nieuwegein) = V(N3_MERRA) N4_MERRA V(Nieuwegein) = V(N4_MERRA) Table 12. Correlation equations and coefficients among Nieuwegein met mast and MERRA nodes. Page 14 of 63

15 According to the obtained results, the long-term wind speed value estimation for Nieuwegein met mast was calculated taking into account the 4 MERRA nodes, all of them with a high correlation coefficient. The table below shows the average wind speed value for the selected reference period, the long-term wind speed values estimated using each MERRA node and the discrepancy of the wind speed values. Met Mast LT Reference WS LT (m/s) WS Ref. P. (m/s) Discrepancy (%) Nieuwegein N1_MERRA N2_MERRA N3_MERRA N4_MERRA Table 13. Long-term wind speeds, reference period wind speed and discrepancies Comparative among the reference met station and MERRA nodes results. Regarding the previous long-term calculations, a few differences appear between the obtained results using the reference met station data and MERRA nodes data. Taking into account that the measurement period of MERRA nodes (30 years) is longer than the measurement period of the reference met station (only 13 years), and in order to check if the reference met station is representative enough of long-term behaviour at the site, linear correlations among monthly average wind speed values from the reference met station and MERRA nodes data have been calculated. Only months with high data availability (90% and above) have been considered. In the following table the monthly correlation coefficients and equations obtained among the reference met station and the 4 MERRA nodes are shown. Met Mast LT Reference Correlation equation R 2 Data (days) Reference Met Station N1_MERRA V(Ref_Station) = V(N1_MERRA) N2_MERRA V(Ref_Station) = V(N2_MERRA) N3_MERRA V(Ref_Station) = V(N3_MERRA) N4_MERRA V(Ref_Station) = V(N4_MERRA) Table 14. Correlation equations and coefficients among the reference met station and MERRA nodes. According to the obtained results, the long-term wind speed value estimation for the reference met station was calculated taking into account the 4 MERRA nodes, all of them with a high correlation coefficient. The table below shows the historical average wind speed for the reference met station, the long-term wind speeds value estimated using each MERRA node and the discrepancy of the wind speed values. Page 15 of 63

16 Met Mast LT Reference WS LT (m/s) WS Hist. (m/s) Discrepancy (%) Reference Met Station N1_MERRA N2_MERRA N3_MERRA N4_MERRA Table 15. Long-term wind speeds, measurement period wind speed and discrepancies. According to the results shown in the previous table, the measurement period of the reference met station is less windy than an average year. In this sense, the historical wind speed values registered at the available reference met station are not representative enough of long-term behaviour at the site Conclusions Considering all the previous discussion, the long-term wind speed value estimation for Nieuwegein met mast was calculated taking into account the results obtained with the 4 MERRA nodes, obtaining an average value considering all of them. In this way, the reference period at Nieuwegein met mast was considered 3.0 % windier than an expected average year. Therefore, a correction factor has been applied to the data series of Nieuwegein met mast for correcting the long-term wind speed. This conclusion has been taken into account in the forthcoming AEP estimations. Page 16 of 63

17 3.3. Analysis of the reference period In this section the results of the data analysis for the reference period of Houten and Nieuwegein met masts are shown. In APPENDIX II: Wind data statistics. Reference period. the comprehensive results of the wind data analysis of the selected reference period at Houten Wind Farm are shown at measurement and hub height Nieuwegein met mast (70 m) During the reference period, the station contains valid filtered and regenerated data at 70 m height, with an average wind speed of 6.05 m/s. The distribution of wind frequencies as a function of wind speed bins at 70 m is represented in the following figure. It can be seen that above the cut-in wind speed (4 m/s) for the wind turbine model considered, the wind frequency during the reference period is 80.9 % Frequency(%) Duration (%) Wind Speed (m/s) Figure 6. Observed wind speed frequency distribution and wind speed duration curve at 70 m during the reference period. Nieuwegein met mast. The fitted Weibull distribution parameters correspond to a scale parameter (A) of 6.7 m/s and a shape parameter (k) of Page 17 of 63

18 In the following figure the wind direction rose and wind speed rose are shown. NNW Frequency (%) 18% N NNE NNW Wind Speed (m/s) 9 N NNE WNW 12% ENE WNW 6 ENE 6% 3 W 0% E W 0 E WSW ESE WSW ESE SSW SSE SSW SSE S S Figure 7. Wind direction rose and wind speed rose at 70 m during the reference period. Nieuwegein met mast. The energy rose is represented below. The most energetic sectors are SSW and S with 22.8 % and 21.4 % respectively. Energy (%) NNW 24% N NNE WNW 16% 8% ENE W 0% E WSW ESE SSW SSE S Figure 8. Wind energy rose at 70 m with Vestas V MW wind turbine model during the reference period. Nieuwegein met mast. Page 18 of 63

19 Houten met mast (10 m) During the reference period, the station contains valid filtered and regenerated data at 10 m height, with an average wind speed of 4.19 m/s. The distribution of wind frequencies as a function of wind speed bins at 10 m is represented in the following figure. It can be seen that above the cut-in wind speed (4 m/s) for the wind turbine model considered, the wind frequency during the reference period is 47.4 % Frequency(%) Duration (%) Wind Speed (m/s) 0 Figure 9. Observed wind speed frequency distribution and wind speed duration curve at 10 m during the reference period. Houten met mast. The fitted Weibull distribution parameters correspond to a scale parameter (A) of 4.6 m/s and a shape parameter (k) of Page 19 of 63

20 In the following figure the wind direction rose and wind speed rose are shown. NNW Frequency (%) 18% N NNE NNW Wind Speed (m/s) 6 N NNE WNW 12% ENE WNW 4 ENE 6% 2 W 0% E W 0 E WSW ESE WSW ESE SSW SSE SSW SSE S S Figure 10. Wind direction rose and wind speed rose at 10 m during the reference period. Houten met mast. The energy rose is represented below. The most energetic sectors are SSW and WSW, with 28.1 and 25.5 % respectively. Energy (%) NNW 30% N NNE WNW 20% 10% ENE W 0% E WSW ESE SSW SSE S Figure 11. Wind energy rose at 10 m with Vestas V MW wind turbine model during the reference period. Houten met mast. Page 20 of 63

21 3.4. Wind shear It is assumed that the wind varies with the height following the next potential law. h V 2 V1 h being V i = Wind speed at level i. h i = Measurement height at level i. = Exponent of the potential law. A filter has been applied to the wind speed, considering only values greater or equal to 3 m/s. Therefore, this calculation method does not distort the profile, since alphas in calm periods are excluded. The considered data correspond to the available measurement period (from 12/09/2013 to 15/03/2014). It is important to note that only measurement data have been used for the wind shear calculation (regenerated data have not been taking into account). Since Houten met mast presents just 1 cup anemometer at 10 m, it is not possible to apply the calculation method in order to obtain the wind shear for this met mast location Nieuwegein met mast Nieuwegein met mast presents 4 cup anemometers at 70, 68.5, 58.6 and 30 m. All the anemometers have been installed on horizontal booms with SSW orientation except the anemometer at 70 m that is on top. Next table shows the frequency, wind speed at each measurement height and exponent values, by sector, calculated for each pair of measurement heights during the available measurement period. SECTOR F (%) 70 m Wind Speed (m/s) 2 1 Wind shear exponent ( ) 70 m 68.5 m 58.6 m 30 m 70.0/ / / / /30.0 N NNE ENE E ESE SSE S SSW WSW W WNW NNW TOTAL 100% Table 16. Shear exponent by sector and overall shear exponent for the measurement period. Nieuwegein met mast. Page 21 of 63

22 The following figure shows a comparison of the different wind shears calculated between measurement heights. NNW Wind shear rose N NNE WNW ENE W E WSW ESE SSW SSE S alfa70.0/58.6 alfa70.0/30.0 alfa68.5/58.6 alfa68.5/30.0 alfa58.6/30.0 Figure 12. Wind shear rose by sectors. Nieuwegein met mast. As it can be seen in the previous figure, wind shear values seem to be affected in sectors ENE and E, probably due the presence of several large trees located in the East direction of the Nieuwegein met mast. Moreover, the calculated wind shear values between 70 and 58.6 m, and 68.5 and 58.6 m have not been considered due to the short vertical gap (ΔZ 10 m). Considering all the previous discussion, ENE and E sectors results have been corrected taking into account the probable affection of the trees and the nearby highway embankment. The affected values have been substituted by the averaged wind shear value of the non-affected sectors. The following table shows the frequency, the exponent values obtained for each sector during the available measurement period and the distribution of wind shear values by sectors: Page 22 of 63

23 SECTOR F (%) 70 m Wind shear 70.0/ / /30.0 N NNE ENE E ESE SSE S SSW WSW W WNW NNW TOTAL 100% Wind shear rose N NNW NNE WNW ENE W WSW E ESE SSW SSE S alfa70.0/30.0 alfa68.5/30.0 alfa58.6/30.0 Figure 13. Frequency, wind shear exponent by sector and wind shear rose for Nieuwegein met mast. In view of the obtained results, the wind shear coefficient considered in the present study to extrapolate the wind speed values to the considered hub height (105 m) will be the one measured between 70 and 30 m levels. It seems to follow a similar trend than the others profiles, and is the one that considers more atmospheric layer (ΔZ = 40 m), including the highest and most representative level, 70 m. The overall value of the wind shear exponent (considering all sectors) is 70/30 = Using the wind shear exponent defined previously, the expected average wind speed at Nieuwegein met mast, at 105 m hub height, during the reference period is 7.01 m/s. Moreover, after applying the considered long-term correction, the obtained average wind speed is 6.80 m/s. Taking into account that the measurement period of Nieuwegein met mast is not too long (only 6 months between September 2013 and March 2014) and the wind shear results have been obtained considering only this measurement period, the previous results have been checked with a reference met station located near the site (with a long measurement period) in order to check if the Nieuwegein results are representative enough of an average year at the site. In this sense, the wind shear exponent values obtained at Nieuwegein met mast during its measurement period are representative of an average year at the site. Page 23 of 63

24 4. AIR DENSITY Air density has a special relevance since the energy yield estimated by a wind turbine is directly proportional to the air flow density which crosses through it. Temperature data at Nieuwegein met mast position are available. However, since less than one year of values have been registered (only 4 months between October 2013 and January 2014), Nieuwegein met mast was not taken into account for the average air density estimation, but it has been considered to check the obtained results Apart from Nieuwegein met mast data, temperature data from a reference met station located near the site are available. So in the present study, the average air density has been estimated using the temperature values registered at the reference met station during 13 years, from January 2001 to March Next table shows the monthly average temperature for the reference met station. TEMP (ºC) Jan 3.7 Feb 4.2 Mar 6.4 Apr 10.1 May 13.2 Jun 15.9 Jul 18.1 Aug 18.0 Sep 15.5 Oct 11.7 Nov 7.7 Dec 4.0 Total Mounthly Temperature ( º C) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Table 17. Average monthly temperature considering the reference met station data at 80 m height. To extrapolate these results to the wind farm site, the average elevation of Houten Wind Farm (0 m) and the hub height (105 m) have been taken into account. The obtained average temperature and air density values have been checked taking into account the Nieuwegein met mast data from October 2013 to January 2014, with similar results in both cases. Considering the previous results, the estimated average air density value for the wind farm site is kg/m 3. The power curve used in the energy study for the wind turbine model Vestas V MW has been provided by the customer. In this case, the power curve is at standard air density: kg/m 3. Final production estimates have been corrected 3 due to the difference between the air density value estimated for the wind farm and the power curve used in the calculus. 3 No correction has been applied to the power curve, since the estimated air density is quite similar to the standard value. However, an equivalent correction has been applied to energy estimate. Page 24 of 63

25 5. ENERGY YIELD CALCULATION The wind resource and energy assessment have been carried out with WAsP 9 Software (Wind Atlas Analysis and Application Program) developed by the DTU Risø (Technical University of Denmark) and used to create the European Wind Atlas Input data of WAsP model In order to determine the wind resource and the energy yield, WAsP model requires the input of data. These inputs are described in the following sections Topography and roughness data A topography map of the site has been downloaded by CIRCE with Global Mapper software. Besides, a roughness map has been defined by CIRCE taking into account the customer indications and different satellite imagery. The values used to define roughness, according to WAsP specifications, are shown below: m: water m: open areas with few windbreaks m: open areas with few houses m: forest m: city (suburbs) Meteorological data Data recorded and regenerated over the reference period at 70 m in Nieuwegein met mast were considered for modelling the site. Subsequently, data extrapolated to hub height (105 m) with the selected wind shear exponent have been set up as input to the numerical WAsP model. Houten met mast has been dismissed because its measurement level (10 m) is considered less representative than Nieuwegein upper measurement level (70 m). However, it will be useful to check the wind flow model in its vicinity if it is necessary and to analyse the noise restriction conditions in the site Wind turbines layout To estimate the wind farm results, the Houten Wind Farm layout (RD Rijks-Driehoek) provided by the customer has been considered. Besides, the Nieuwegein Wind Farm layout (RD Rijks-Driehoek), provided by the customer, has also been taken into account in the energy yield assessment for the wake losses estimation of Houten Wind Farm. Page 25 of 63

26 The following tables show the considered layouts: Wind Turbine Coordinates (RD) X (m) Y (m) H H H Table 18. Houten Wind Farm layout provided by the customer. Wind Turbine Coordinates (RD) X (m) Y (m) N N N N N Table 19. Nieuwegein Wind Farm layout provided by the customer. The following figure shows the map including Houten W.F. and Nieuwegein W.F. in which the contour lines and wind turbine layouts are represented. Figure 14. Houten and Nieuwegein wind turbine layouts. Contour lines every 5 m. Page 26 of 63

27 5.2. Wind Turbine Power Curves The following wind turbine power curves have been used in the WAsP model. Houten Wind Farm: Vestas V MW Grid Streamer, for an air density of = kg/m 3 Speed (m/s) Power (kw) Ct Power (kw) Speed (m/s) 0.4 Ct Figure 15. Vestas V MW Grid Streamer. Power Curve for an air density of = kg/m 3. Nieuwegein Wind Farm: Vestas V MW 50 Hz VCS, for an air density of = kg/m 3. Speed (m/s) Power (kw) Ct Power (kw) Speed (m/s) 0.4 Ct Figure 16. Vestas V MW 50 Hz VCS. Power Curve for an air density of = kg/m 3. Page 27 of 63

28 5.3. WAsP model correction requirements As all numerical simulations, WAsP generates some errors, especially estimating the wind speed distribution at met station and the annual estimated production for each turbine of the wind farm. For this reason some calculations have to be carried out in order to adjust the model s results. The following table shows the discrepancies obtained in wind speed and production and the corresponding correction factors Nieuwegein meteorological mast Wind Speed Adjustment Height (m) Theoretical W.S. (m/s) WAsP W.S. (m/s) Error (%) Production Adjustment WT Model Theoretical prod. (MWh) WAsP prod. (MWh) Error (%) V90-2.0MW 105 m Table 20. WAsP correction factors for Nieuwegein met mast WAsP model results The following section shows the coordinates, average wind speed values, gross productions, wake effects and net productions (considering the losses) for Houten Wind Farm. The gross production obtained by the WAsP model has been reduced by a factor of 31.4%. The losses considered are: 0.8 % losses due to electrical efficiency % losses due to noise curtailments. 2.1 % losses due to shadow flicker curtailments (including shutdown strategy defined by CIRCE). 3.6 % other losses (non-availability, turbine performance, environmental ). In APPENDIX III: Noise curtailments losses study and APPENDIX IV: Shadow flicker losses study, a detailed study of the considered noise and shadow flicker losses estimated are shown. In _PLA_Houten_WF.pdf report, a detailed study of considered losses due to electrical efficiency and others (non-availability, turbine performance, environmental ) are shown. These losses have been estimated considering the operational data recorded at each wind turbine of Houten Wind Farm during the period 01/08/2013 to 28/02/2014, which have been provided by the customer. Page 28 of 63

29 Besides, the production results have been corrected due to the difference between the estimated air density value (1.229 kg/m 3 ) and the standard air density value (1.225 kg/m 3 ) Houten Wind Farm production results. The following table shows the coordinates, average wind speed values, gross productions, wake effects (considering Houten wind turbines, considering the nearby Nieuwegein wind turbines influence and considering both wind farms) and net productions (considering the previously defined losses) for Houten Wind Farm. Turbine X (m) Y (m) LT Wind speed (m/s) Gross AEP (MWh/year) Wakes (%) Houten WF Wakes (%) Nieuwegein WF Wakes (%) WF AEP (MWh/year) AEP P50 (MWh/year) Equivalent FLH H H H Houten W.F. Wind Speed 6.84 m/s Turbine model Vestas V90-2.0MW Wake losses 2.5 % Hub height 105 m AEP P MWh/year W.F. capacity 6.0 MW Equivalent FLH 1969 Hours Table 21. Production results for Houten W.F. Vestas V MW at 105 m. Page 29 of 63

30 6. UNCERTAINTY STUDY In the present section an estimate of the uncertainty associated with the results for Houten Wind Farm has been developed. Results are shown for the selected wind turbine model: Vestas V MW at 105 m hub height. The parameters considered in the uncertainty study, for both wind speed and production estimates, are shown below: Wind speed uncertainty σ (%) Anemometer calibration 0.5 Type of anemometer 0.5 Mounting of equipment 0.5 Wind shear 2.0 Long term 4.0 Model 1.0 TOTAL 10.2 Table 22. Uncertainties associated with wind speed. Production uncertainty σ (%) Wind farm wake effect 0.5 Power curve 1.0 Air density 0.5 Others (noise, shadow, hysteresis ) 4.0 TOTAL 4.2 Table 23. Uncertainties associated with production. The wind speed uncertainty value is referred to wind speed. In order to extrapolate the considered value to production, the power curve of the considered wind turbine has been considered as well as the site s wind distribution. The global uncertainty value applied to the wind farm production corresponds to: Uncertainty over production σ (%) TOTAL 11.0 Table 24. Uncertainty (%) results. Taking into account the previous considerations, the obtained production percentiles results over a long term period of 1, 10 and 20 years are shown in the next table: Percentil P50 P90 AEP (MWh/year) Equivalent FLH AEP (MWh/year) Equivalent FLH 1 year years years Table 25. Production results and estimated equivalent full load hours by percentiles. Page 30 of 63

31 7. CONCLUSIONS The description of the main results obtained in the present wind resource and energy yield assessment study for Houten Wind Farm are shown below. Wind data analysis Two meteorological masts, Nieuwegein and Houten, provided by the customer have been considered. The considered measurement period of each meteorological mast is - 6 months at Nieuwegein met mast, from 12/09/2013 to 15/03/ months at Houten met mast, from 23/10/2013 to 28/02/2014. Definition and selection of the reference period Due to the low period of measurement data in Nieuwegein and Houten met masts, ten-minute correlation analyses between Nieuwegein and Houten met masts and a nearby reference met station, with a long period of measured data, have been carried out to obtain at least 1 year of wind data in each meteorological mast. In this sense, a common 1-year period for the two meteorological masts, from March 2013 to February 2014, has been selected as the reference period for the study. In order to establish if the 1-year regenerated period is representative of the wind conditions at the site, a long term study, using the total measurement period of the available reference met station (13 years), as well as MERRA data (30 years), has been performed. According to the obtained results, the reference period in Nieuwegein met mast is 3.0 % windier than an average year. Air density The average air density in Houten Wind Farm site, taking into account the available temperature of the reference met station located near the site has been estimated. The average air density value at the site is kg/m 3. Final production values have been corrected due to the difference between the value of estimated air density (1.229 kg/m 3 ) and the available power curves used in the calculations (1.225 kg/m 3 ). Page 31 of 63

32 WAsP model input data A layout of 3 wind turbines (Houten Wind Farm) provided by the customer have been evaluated considering the next wind turbine model: - Vestas V MW at 105 m hub height. Besides, 5 neighbouring wind turbines (Nieuwegein Wind Farm) also provided by the customer have also been taken into account in the energy yield assessment for the wake loss estimation of Houten Wind Farm. A digitalized topography map has been obtained by CIRCE from Global Mapper software, and a roughness map has been defined by CIRCE. WAsP model results The production for the proposed layout and the efficiency of the turbines considering wake losses (from Houten Wind Farm and from the nearby Nieuwegein Wind Farm) and technical losses have been estimated (WAsP v. 9.1). A 31.4 % reduction factor has been applied to the gross production obtained by the WAsP model, due to losses for electrical efficiency, noise, shadow and other (non-availability, turbine performance, environmental ). Besides, final production values have been corrected due to the difference between the value of estimated air density (1.229 kg/m 3 ) and the available power curves (1.225 kg/m 3 ). The results are shown in the table below. Wind Farm Wind Turbine Model WF Capacity (MW) WF Wind Speed LT (m/s) Wakes (%) AEP P50 (MWh/year) Equivalent FLH Houten Vestas V90-2.0MW Table 26. Results obtained for Houten Wind Farm. Page 32 of 63

33 Uncertainty results It s important to point out the high level of uncertainty in the results, with a global uncertainty value of 11.0 %. This value is due to the low period of measurement data in Nieuwegein (around 6 months) and Houten (around 4 months) met masts, and due to the high noise losses value (26.7 %) obtained, which increases the uncertainty of the results. In this sense, if a longer measurement campaign was carried out, more reliable results were expected, reducing the associated uncertainties. The following table shows the production percentiles for the obtained results over a long term period of 1, 10 and 20 years. Percentil P50 P90 AEP (MWh/year) Equivalent FLH AEP (MWh/year) Equivalent FLH 1 year years years Table 27. Production results and estimated equivalent full load hours by percentiles. Page 33 of 63

34 APPENDIX I: WIND DATA ANALYSIS AND TREATMENT Page 34 of 63

35 1.1. Met mast and sensors characteristics Nieuwegein met mast Nieuwegein meteorological mast is equipped with 4 Thies cup anemometers mounted at 70, 68.5, 58.6 and 30 m. All the anemometers are installed on horizontal booms except the anemometer at 70 m, that it is mounted on top. The orientation of the anemometers at 68.5 m, 58.6 m and 30 m is 203º, 208º and 208º respectively. Two Thies wind vanes are mounted at 68.4 and 29.9 m. The calibration reports have been supplied for all the anemometers, and the calibration parameters have been applied to the datalogger. All the anemometers have been calibrated by MEASNET calibration procedure. All devices are installed in a tubular mast 70 meters high. The mast type and model is Telescopic, WHTER-80 m double T. The table below shows the characteristics of the sensors found on the met mast. Met mast Sensor Level (m) Model Data period Serial number Boom orientation (º) Boom lenght (m) Calibration parameter Slope Offset Top Cup anemometer Thies First Class Adv ( ) Wind vane Thies First Class ( ) Nieuwegein Baromether 5.50 Ammonit AB 60 B /09/2013 Galltec-Mela Thermometer to KPC1.S/6-ME 15/03/2014 MC Technol. Modem TC63i Datalogger 5.50 Ammonit (METEO-32) C Solar Panel ET Solar Group 20 W Lightning protection Beacon light Table I-1. Nieuwegein met mast characteristics. Page 35 of 63

36 In the next figure, the view from Nieuwegein met mast to the four main directions (N-E- S-W) is shown. Figure I-1. Environmental view in Nieuwegein met mast. Page 36 of 63

37 Figure I-2. Nieuwegein met mast. Page 37 of 63

38 Houten met mast Houten meteorological mast is equipped with 1 combined wind sensor. This wind sensor combines a cup anemometer and a wind vane on a single bracket. The wind sensor is mounted on top at 10 m. The calibration report has been supplied for the anemometer, and the calibration parameters have been applied to the datalogger. The anemometer has been calibrated by MEASNET calibration procedure. All devices are installed in a tubular mast 10 meters high. The table below shows the characteristics of the sensors found on the met mast. Met mast Houten Sensor Level (m) Model Data period Serial number Boom orientation (º) Boom lenght (m) Calibration parameter Cup /10/2013 J Top anemometer Mierij Meteo to MW 21 Wind vane /02/ Top - - Slope Offset Table I-2. Nieuwegein met mast characteristics Quality control of the wind data Nieuwegein met mast The measurement period of this met mast goes from 12/09/2013 to 15/03/2014. After the statistical treatment of the meteorological data, the major incidences observed are the following: All cup anemometers registered several erroneous values during the following dates: - On 06/01/ On 09/01/ On 15/01/ On 17/01/2014. The anemometer mounted at 58.6 m registered erroneous data for the following period: - From 05/02/2013 to 20/02/ Houten met mast The measurement period of this met mast goes from 23/10/2013 to 28/02/2014. After the statistic treatment of the meteorological data, there are not relevant incidences in this period. Page 38 of 63

39 1.3. Monthly average wind speed values In the table below, the monthly average wind speed, accumulated average wind speed, availability and number of data for each measurement level in Nieuwegein and Houten met masts are shown Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m Data % 61% 100% 100% 100% Nieuwegein m Data % 61% 100% 100% 100% Nieuwegein Data % 61% 100% 100% 100% Nieuwegein m Data % 61% 100% 100% 100% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m Data % 97% 96% 40% Nieuwegein m Data % 97% 96% 40% Nieuwegein m Data % 95% 43% 40% Nieuwegein m Data % 97% 96% 40% Accumulated W.S. Nieuwegein m Data % 85% Nieuwegein m Data % 85% Nieuwegein m Data % 77% Nieuwegein m Data % 85% Table I-3. Monthly averaged wind speed, accumulated averaged wind speed, availability and number of data for each measurement level of Nieuwegein met mast (original filtered data) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m Data % 27% 99% 100% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m Data % 100% 100% Accumulated W.S. Houten m Data % 85% Table I-4. Monthly averaged wind speed, accumulated averaged wind speed, availability and number of data for each measurement level of Houten met mast (original filtered data). Page 39 of 63

40 2013 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m regenerated Data % 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Nieuwegein m Data % 61% 100% 100% 100% Nieuwegein Data % 61% 100% 100% 100% Nieuwegein m Data % 61% 100% 100% 100% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nieuwegein m regenerated Data % 100% 100% 40% Nieuwegein m Data % 97% 96% 40% Nieuwegein m Data % 95% 43% 40% Nieuwegein m Data % 97% 96% 40% Accumulated W.S. Nieuwegein m regenerated Data % 95% Nieuwegein m Data % 85% Nieuwegein m Data % 77% Nieuwegein m Data % 85% Table I-5. Monthly averaged wind speed, accumulated averaged wind speed, availability and number of data for each measurement level of Nieuwegein met mast (original filtered and regenerated data) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m regenerated Data % 100% 100% 100% 94% 100% 100% 100% 100% 100% 100% 2014 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Houten m regenerated Data % 100% 100% Accumulated W.S. Houten m regenerated Data % 99% Table I-6. Monthly averaged wind speed, accumulated averaged wind speed, availability and number of data for each measurement level of Houten met mast (original filtered and regenerated data). Page 40 of 63

41 APPENDIX II: WIND DATA STATISTICS. REFERENCE PERIOD. Page 41 of 63

42 Nieuwegein met station (70 m) Site: Houten Data period covered: 1/ 3/ / 2/2014 Total Number of data: SUMMARY Level (m): 70 m Average wind speed (m/s): 6.05 A Weibull scale parameter (m/s): 6.7 k Weibull shape parameter: 2.34 Maximum wind speed (m/s): 22.8 Maximum wind speed direction: SSW Average power (kw) - V90-2.0MW: Capacity factor (%) - V90-2.0MW: 24.9% Prevailing direction sectors: SSW 16.26% 6.99 m/s S 13.90% 7.23 m/s Page 42 of 63

43 POWER DENSITY FUNCTION Wind speed (m/s) Frequency (%) Duration Curve (%) Page 43 of 63

44 DIRECTIONAL DISTRIBUTION Sector Frequency (%) Average W.S. (m/s) Energy (MWh) V90-2.0MW N 6.30% NNE 7.41% ENE 6.08% E 7.16% ESE 4.83% SSE 7.04% S 13.90% SSW 16.26% WSW 12.63% W 6.64% WNW 5.30% NNW 6.45% REFERENCE PERIOD AVERAGE DAY Hour Average W.S. Average power(kw) (m/s) V90-2.0MW Page 44 of 63

45 Nieuwegein met station (105 m) Site: Houten Data period covered: 1/ 3/ / 2/2014 Total Number of data: SUMMARY Level (m): 105 m Average wind speed (m/s): 7.01 A Weibull scale parameter (m/s): 7.8 k Weibull shape parameter: 2.42 Maximum wind speed (m/s): Maximum wind speed direction: WSW Average power (kw) - V90-2.0MW: Capacity factor (%) - V90-2.0MW: 35.2% Prevailing direction sectors: SSW 16.26% 7.87 m/s S 13.90% 8.27 m/s Page 45 of 63

46 POWER DENSITY FUNCTION Wind speed (m/s) Frequency (%) Duration Curve (%) Page 46 of 63

47 DIRECTIONAL DISTRIBUTION Sector Frequency (%) Average W.S. (m/s) Energy (MWh) V90-2.0MW N 6.30% NNE 7.41% ENE 6.08% E 7.16% ESE 4.83% SSE 7.04% S 13.90% SSW 16.26% WSW 12.63% W 6.64% WNW 5.30% NNW 6.45% REFERENCE PERIOD AVERAGE DAY Hour Average W.S. Average power(kw) (m/s) V90-2.0MW Page 47 of 63

48 Houten met mast (10 m) Site: Houten Data period covered: 1/ 3/ / 2/2014 Total Number of data: Number of erroneous data: 284 SUMMARY Level (m): 10 m Average wind speed (m/s): 4.19 A Weibull scale parameter (m/s): 4.6 k Weibull shape parameter: 1.93 Maximum wind speed (m/s): Maximum wind speed direction: WSW Average power (kw) - V90-2.0MW: Capacity factor 4 (%) - V90-2.0MW: 9.7% Prevailing direction sectors: SSW 17.55% 4.93 m/s WSW 13.75% 5.13 m/s 4 The Capacity factor (%) is a theoretical calculation so that in some cases does not take a physical interpretation due to the impossibility of install a wind turbine at some specific hub height (10 m in this case). Page 48 of 63

49 POWER DENSITY FUNCTION Wind speed (m/s) Frequency (%) Duration Curve (%) Page 49 of 63

50 DIRECTIONAL DISTRIBUTION Sector Frequency (%) Average W.S. (m/s) Energy (MWh) V90-2.0MW N 7.03% NNE 6.99% ENE 5.84% E 6.15% ESE 4.89% SSE 6.05% S 12.87% SSW 17.55% WSW 13.75% W 7.04% WNW 5.47% NNW 6.37% REFERENCE PERIOD AVERAGE DAY Hour Average W.S. Average power(kw) (m/s) V90-2.0MW Page 50 of 63

51 APPENDIX III: NOISE CURTAILMENTS LOSSES STUDY Page 51 of 63

52 This appendix shows the calculation of the noise curtailment losses factor for the wind turbines located at Houten Wind Farm. The noise curtailments losses study has been carried out taking into account the following data: - Filtered and regenerated data from Nieuwegein met mast for the reference period. - Filtered and regenerated data from Houten met mast for the reference period. - Power curve of the studied wind turbine model: Vestas V MW Grid Streamer for an air density of = kg/m 3. Besides the previous data, the noise curtailments shown below have been provided by the customer in order to obtain the noise losses at the wind farm: Noise curtailment Time range Curtailment 1 07:00-23:00 h Power curve noise Mode :00-07:00 h Power curve noise Mode :00-07:00 h Power curve noise Mode 0 if V 10 m > 6.5 m/s 4 00:00-24:00 h Shutdown if V 10 m < 3.5 m/s 5 00:00-24:00 h Shutdown if V 10 m < 4.5 m/s and V 105 m > 7.5 m/s Table III-1. Noise curtailments provided by the customer. The following assumptions have been considered in order to calculate the noise regulation losses factor of the wind turbines: - Filtered and regenerated data from Nieuwegein met mast at 70 m and Houten met mast at 10 m during the reference period (01/03/2013 to 28/02/2014) have been considered to obtain the noise curtailments losses. In both cases, long term correction was not applied. - Taking into account the different time ranges considered in the noise curtailment provided by the customer and the expected different behaviour among the wind data recorded throughout a day, 3 different wind shear exponent factors (considering day/evening/night periods) have been calculated for Nieuwegein met mast in order to obtain a more reliable wind data series at the proposed hub height (105 m). In this way, next table shows the 3 time ranges considered and the obtained average wind shear exponents. They have been used to extrapolate the filtered and regenerated data from Nieuwegein met mast during the reference period from 70 m (measurement height) to 105 m (hub height): Time period Time range Wind shear ( ) Day 07:00-19:00 h Evening 19:00-23:00 h Night 23:00-07:00 h Table III-2. Wind shear exponents for the 3 considered time ranges. Page 52 of 63

53 - In order to obtain a more reliable wind data series at the position of each wind turbine, a ratio between Nieuwegein met mast and each wind turbine position wind speed values has been calculated. To obtain these ratios WAsP wind speed values at 105 m hub height have been considered. The following table shows the discrepancies (%) between WAsP wind speed values at Nieuwegein met mast and at each wind turbine position (at 105 m hub height in all cases): Position WAsP W.S. Discrepancy (m/s) (%) Nieuwegein H % H % H % Table III-3. Discrepancies (%) between WAsP wind speed values at Nieuwegein met mast and at each wind turbine position. - From each generated wind data series and the proposed power curve, (Vestas V MW Grid Streamer) 3 new power data series have been obtained. These series contain the 10-minute power corresponding to each wind turbine position during the reference period when any noise curtailment is not applied (power curve noise Mode 0). - Finally, the noise curtailments provided by the customer (Table III-1) have been applied over the previous 10-minute power data series in order to calculate the noise regulation losses factor for the wind turbines. According to the previous assumptions and the obtained results, the following table shows, for each wind turbine and for Houten Wind Farm, the gross production without considering any noise curtailment, the gross production considering the noise curtailments provided by the customer and the obtained noise regulation losses factors in each case: WTG No curtailment Noise curtailment Noise losses Gross AEP (MWh/y) Gross AEP (MWh/y) (%) H % H % H % TOTAL % Table III-4. Noise losses factors for Houten Wind Farm. In this sense, an average noise regulation losses factor of 26.7 % has been applied to the gross production results obtained by the WAsP model for Houten Wind Farm. Page 53 of 63

54 Taking into account the 3 time periods defined previously (day/evening/night periods), the following table shows, for each time period, the gross production without considering any noise curtailment, the gross production considering the noise curtailments provided by the customer and the obtained noise regulation losses factors in the own time periods: Time No curtailment Noise curtailment Noise losses Time range Period Gross AEP (MWh/y) Gross AEP (MWh/y) (%) Day 07:00-19:00 h % Evening 19:00-23:00 h % Night 23:00-07:00 h % TOTAL 00:00-24:00 h % Table III-5. Noise losses factors for the 3 considered time ranges at Houten Wind Farm. Moreover, the following table shows the obtained noise losses percentages for each time periods (day/evening/night periods) regarding to the whole noise regulation losses: Time Period Time range Noise losses (%) Day 07:00-19:00 h 20.9% Evening 19:00-23:00 h 25.2% Night 23:00-07:00 h 53.8% Table III-6. Noise losses factors for the 3 considered time ranges regarding to the whole noise regulation losses. As it can be seen in the previous table, the most noise losses (%) happen during the night period (more than 50 %), although this time interval includes only 8 h (33% of a whole day). If we consider both evening and night time ranges (19h-7h), they gather 79.0 % of noise losses in the 50 % of the considered time range. Page 54 of 63

55 APPENDIX IV: SHADOW FLICKER LOSSES STUDY Page 55 of 63

56 This appendix shows the calculation of the shadow flicker modelling analysis of the wind turbines at the surrounding area of Houten Wind Farm. The shadow flicker modelling analysis was conducted using WindPRO 2.9 basis software. Input variables and assumptions used for shadow flicker modelling calculations for the proposed Houten Wind Farm include: - WTG coordinates 5 : 3 V MW wind turbine generators at 105 m hub height. - Digital map of the site. - Shadow flicker reception points have been implemented by CIRCE 6, considering the info provided by the customer. - Max. shadow flicker affected period over each considered building is 0 hours per year. - Each building has been simulated as a window defined in WindPRO with the following parameters 7 : o Greenhouse: The window is affected by the shadows regardless the direction where they come from. o Window height above ground (0 in the majority of cases). o Window height. It corresponds approx. with the height of the building 8. o Window width. It corresponds approx. with the width of the building facade 2. o Angle of inclination of the window from the ground (90º in all cases). - There is no shadow flicker impact when the sun s elevation is less than 3 degrees above the horizon (due to the scattering effect of the atmosphere on low angle sunlight). - There is no shadow flicker impact when less than 20 percent of the sun is masked by the turbine blades because this is not enough masking to create a detectable shadow. WindPRO model calculates the distance of projection of shadows automatically from the geometry of the turbine blade model (Vestas V MW) with the following parameters provided by the manufacturer 9 : o Maximum chord length = 3.5 m o Chord length at 90 % blade length = 0.9 m. 5 The coordinate system is Rijks-Driehoek (RD). 6 Based on information about the position and dimensions of the considered buildings provided by the customer in the file Houten-shadow.gmw. The total number of studied shadow reception points is For the study, buildings that are outside the 0 hours per year iso-shadow line were not considered. 7 Some buildings have been simulated considering various shadow reception points. 8 The height of each building has been estimated considering 3 meters per floor, and taking into account the following information: website, pictures provided by the customer and street view pictures extracted from Google Earth tool. 9 Document App 2.1 General Specification V MW V MW GridStreamer _V15.pdf. Page 56 of 63

57 WindPRO model offers two methods for calculating shadows: - Worst case (astronomical maximum shadows). The sun is shining always from sunrise to sunset (no clouds), rotor is always 90 oriented to the sun, and all WTGs are operating all the time. This option has been considered to define the 0 hours per year iso-shadow line map and to identify the shadow flicker affected periods. - Expected case based on statistics. This option has been considered to obtain the production losses due to shadow flicker. The calculation was performed considering the expected weather conditions with the following input data: o Probability that the day is sunny, considering the NASA database. In this sense, it is considered that the cloudiness of the region is around 70 %. Monthly averaged insolation clearness index (0 to 1) 10 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Table IV-1. Monthly average insolation clearness index obtained from NASA in Houten W.F. o Operational hours are calculated for the selected WTG model (cut in = 4 m/s for Vestas V MW) using the wind distribution information of Nieuwegein met mast located at the site. The total value of operational hours is 7032 hours. Next table shows these values distributed by sectors. Operational hours distributed by sectors (h) N NNE ENE E ESE SSE S SSW WSW W WNW NNW Table IV-2. Operational hours. Only WTG locations from Houten WF have been considered for the shadow flicker modelling study. Shadow flicker results, for WindPRO worst case option, include different time periods (approx. 2-3 time periods per day), depending on the considered WTG position. However, according to the customer requirements, 60 individual time slots per WTG position have been defined, merging different periods with a similar behaviour. The obtained curtailment tables are shown below. Netherlands winter time (UTC + 1) has been always considered. 10 NASA website: Page 57 of 63

58 Next tables show the time intervals proposed by CIRCE, when each wind turbine should be stopped in order to prevent any shadow flicker over the reception points. Shutdown strategy for H1 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 1 Jan 25 Jan 9:10 9:42 1 Jan 10 Jan 14:56 16:15 11 Jan 20 Jan 15:32 16:32 21 Jan 31 Jan 15:37 16:54 27 Jan 7 Feb 8:37 9:06 1 Feb 12 Feb 16:07 17:18 8 Feb 9 Feb 9:06 9:20 10 Feb 17 Feb 8:32 9:33 13 Feb 28 Feb 16:44 17:49 18 Feb 28 Feb 8:38 9:42 1 Mar 16 Mar 8:29 9:44 1 Mar 14 Mar 16:48 18:15 5 Mar 16 Mar 7:31 8:25 15 Mar 28 Mar 16:58 18:40 17 Mar 28 Mar 7:08 8:25 17 Mar 28 Mar 8:30 9:36 29 Mar 11 Apr 7:59 9:12 29 Mar 29 Mar 9:46 9:59 29 Mar 9 Apr 18:17 19:59 10 Apr 16 Apr 18:37 20:11 12 Apr 23 Apr 8:00 8:57 15 Apr 23 Apr 18:48 20:23 23 Apr 30 Apr 19:05 20:27 1 May 7 May 19:14 20:28 8 May 15 May 19:25 20:27 16 May 21 May 19:39 20:23 22 May 26 May 19:52 20:19 18 Jul 22 Jul 20:00 20:29 23 Jul 31 Jul 19:44 20:36 1 Aug 6 Aug 19:32 20:37 Shutdown strategy for H1 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 7 Aug 12 Aug 19:22 20:37 13 Aug 19 Aug 19:10 20:35 20 Aug 31 Aug 8:00 8:57 20 Aug 26 Aug 18:50 20:28 27 Aug 2 Sep 18:35 20:12 1 Sep 15 Sep 7:55 9:02 3 Sep 6 Sep 18:26 19:57 7 Sep 18 Sep 18:00 19:49 14 Sep 24 Sep 9:15 10:16 16 Sep 30 Sep 7:54 9:08 19 Sep 30 Sep 17:37 19:21 25 Sep 30 Sep 9:09 10:20 1 Oct 9 Oct 8:20 9:03 1 Oct 13 Oct 9:08 10:20 1 Oct 12 Oct 17:22 18:52 13 Oct 24 Oct 17:17 18:24 14 Oct 24 Oct 9:10 10:14 25 Oct 3 Nov 8:02 9:03 25 Oct 28 Oct 16:14 16:58 29 Oct 4 Nov 15:49 16:49 4 Nov 15 Nov 8:07 8:36 5 Nov 12 Nov 15:31 16:36 13 Nov 21 Nov 15:13 16:21 17 Nov 28 Nov 8:48 9:21 22 Nov 27 Nov 15:01 16:08 28 Nov 3 Dec 14:57 16:02 29 Nov 5 Dec 8:54 9:22 4 Dec 31 Dec 14:46 16:02 6 Dec 15 Dec 9:04 9:50 16 Dec 31 Dec 9:15 9:56 Table IV-3. Shutdown strategy, proposed by CIRCE, for H1 WTG of Houten WF. Page 58 of 63

59 Shutdown strategy for H2 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 1 Jan 21 Jan 9:22 10:47 1 Jan 20 Jan 10:48 11:55 1 Jan 9 Jan 14:54 16:14 10 Jan 20 Jan 15:00 16:32 21 Jan 30 Jan 11:00 11:51 21 Jan 31 Jan 15:22 16:54 22 Jan 3 Feb 9:18 10:48 1 Feb 10 Feb 15:55 17:14 4 Feb 14 Feb 9:19 10:39 11 Feb 17 Feb 16:19 17:28 15 Feb 18 Feb 9:26 10:06 18 Feb 28 Feb 16:43 17:50 27 Feb 28 Feb 8:17 8:41 1 Mar 10 Mar 7:51 8:51 1 Mar 10 Mar 17:02 18:09 11 Mar 20 Mar 7:32 8:51 11 Mar 20 Mar 17:37 18:26 21 Mar 28 Mar 7:20 8:26 21 Mar 28 Mar 17:59 18:40 29 Mar 3 Apr 8:17 9:30 29 Mar 9 Apr 19:18 19:59 4 Apr 12 Apr 8:18 9:18 10 Apr 21 Apr 19:42 20:19 13 Apr 16 Apr 8:24 8:51 22 Apr 9 May 19:57 20:47 1 May 7 May 6:30 7:10 8 May 17 May 6:11 7:04 10 May 8 Jun 20:21 21:15 18 May 7 Jun 6:03 6:48 8 Jun 30 Jun 6:19 6:37 Shutdown strategy for H2 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 9 Jun 6 Jul 21:01 21:20 1 Jul 9 Jul 6:16 6:47 7 Jul 19 Jul 20:53 21:23 10 Jul 26 Jul 6:15 6:58 20 Jul 31 Jul 20:36 21:16 27 Jul 5 Aug 6:22 7:15 1 Aug 15 Aug 20:12 21:01 6 Aug 13 Aug 6:40 7:18 14 Aug 21 Aug 6:48 7:17 16 Aug 22 Aug 20:00 20:35 23 Aug 31 Aug 19:44 20:21 27 Aug 9 Sep 8:12 9:14 1 Sep 15 Sep 19:06 20:02 10 Sep 18 Sep 8:09 9:24 16 Sep 30 Sep 18:21 19:28 19 Sep 30 Sep 8:11 9:31 1 Oct 15 Oct 8:24 9:29 1 Oct 11 Oct 17:48 18:52 12 Oct 24 Oct 17:14 18:18 23 Oct 24 Oct 10:10 10:27 25 Oct 3 Nov 8:49 9:58 1 Nov 15 Nov 15:11 16:43 4 Nov 11 Nov 8:49 10:16 12 Nov 23 Nov 8:51 10:23 12 Nov 6 Dec 10:37 11:40 16 Nov 6 Dec 14:43 16:17 24 Nov 8 Dec 9:06 10:27 7 Dec 31 Dec 10:37 11:52 7 Dec 31 Dec 14:43 16:02 9 Dec 31 Dec 9:12 10:36 Table IV-4. Shutdown strategy, proposed by CIRCE, for H2 WTG of Houten WF. Page 59 of 63

60 Shutdown strategy for H3 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 1 Jan 15 Jan 9:20 10:31 1 Jan 15 Jan 12:10 13:35 1 Jan 15 Jan 15:17 16:23 16 Jan 31 Jan 9:15 10:34 16 Jan 31 Jan 12:16 13:43 16 Jan 31 Jan 15:44 16:54 1 Feb 6 Feb 9:17 10:27 1 Feb 22 Feb 12:17 13:44 1 Feb 12 Feb 16:28 17:18 3 Feb 21 Feb 8:24 9:07 7 Feb 12 Feb 9:20 9:49 13 Feb 22 Feb 16:41 17:39 22 Feb 2 Mar 8:24 8:59 23 Feb 28 Feb 12:30 13:33 23 Feb 28 Feb 17:03 17:50 1 Mar 10 Mar 17:21 18:09 11 Mar 16 Mar 17:39 18:19 17 Mar 19 Mar 17:10 17:38 17 Mar 19 Mar 17:52 18:25 20 Mar 25 Mar 16:57 17:57 20 Mar 25 Mar 18:02 18:35 26 Mar 28 Mar 16:53 18:40 28 Mar 30 Mar 17:50 19:43 31 Mar 9 Apr 17:45 19:59 10 Apr 20 Apr 17:45 19:32 10 Apr 20 Apr 19:35 20:10 21 Apr 30 Apr 17:52 19:27 1 May 3 May 18:08 19:10 1 May 3 May 19:50 20:13 4 May 12 May 19:40 20:25 Shutdown strategy for H3 WTG Starting date Ending date Time period Day Month Day Month Hour Hour 13 May 18 May 19:38 20:33 19 May 25 May 19:37 20:36 26 May 31 May 19:38 20:38 1 Jun 15 Jun 19:39 20:42 16 Jun 30 Jun 19:46 20:45 1 Jul 31 Jul 19:47 20:47 1 Aug 12 Aug 19:50 20:35 9 Aug 13 Aug 18:13 19:23 14 Aug 31 Aug 17:46 19:32 23 Aug 31 Aug 19:41 20:12 1 Sep 17 Sep 17:41 20:02 18 Sep 23 Sep 17:44 19:23 24 Sep 30 Sep 17:52 19:09 1 Oct 12 Oct 17:57 18:52 12 Oct 24 Oct 8:54 9:35 13 Oct 24 Oct 12:53 14:10 13 Oct 24 Oct 17:19 18:24 25 Oct 8 Nov 7:56 8:36 25 Oct 27 Nov 11:47 13:15 25 Oct 31 Oct 16:09 16:58 30 Oct 8 Nov 8:48 9:53 1 Nov 12 Nov 15:54 16:43 9 Nov 26 Nov 8:47 10:11 13 Nov 30 Nov 15:18 16:22 27 Nov 16 Dec 9:01 10:15 28 Nov 31 Dec 11:56 13:23 1 Dec 15 Dec 15:07 15:59 16 Dec 31 Dec 15:08 16:02 17 Dec 31 Dec 9:16 10:22 19 Dec 25 Dec 14:40 14:46 Table IV-5. Shutdown strategy, proposed by CIRCE, for H3 WTG of Houten WF. In the next figure the results of the shadow flicker modelling study can be seen, considering the worst case (astronomical maximum shadows) that contains the theoretical number of hours per year that shadow flicker would occur at any given location within the studied area. - In yellow, the wind turbine generator positions. - In red, the 0 hour/year iso-shadow line for the worst case. - In blue, the building contours provided by de customer. - In cyan, the shadow reception points studied by CIRCE. Page 60 of 63

61 Figure IV-1. 0 hour/year iso-shadow line, considering the worst case at Houten Wind Farm (3 V MW at 105 m hub height). Shadow flicker on the reception points caused by each turbine is shown in the next table for worst case and for the expected case, considering the NASA insolation clearness data. Shut-down time (% of time) WTG H1 WTG H2 WTG H3 TOTAL Worst case 6.4 % 6.9 % 7.6 % 7.0 % Expected case statistics (NASA data) 1.6 % 1.6 % 1.9 % 1.7 % Table IV-6. Annual production losses due to shadow flicker shutdown. It must be noted that the limitation to 60 stop intervals per wind turbine leads to an expected increase in the production losses around 24 %. Next table shows these losses applied by WTG including shutdown strategy. These results (for the expected case) have considered in order estimating the expected losses in the energy yield. Shut-down time (% of time) Including shutdown strategy WTG H1 WTG H2 WTG H3 TOTAL Worst case 7.7 % 9.0 % 9.2 % 8.6 % Expected case statistics (NASA data) 1.9 % 2.1 % 2.3 % 2.1 % Table IV-7. Annual production losses due to shadow flicker including shutdown strategy proposed by CIRCE. Page 61 of 63

62 APPENDIX V: ILLUSTRATIONS Page 62 of 63

63 Figure V-1. Houten Wind Farm: wind speed values at 105 m. Page 63 of 63