mengesha

Dear all, i have sent to the manufacturer/ company to get the following wind turbines power curve and thrust coefficient but no body answer me/ give me with long period of time while i am waiting in trouble to do WAsP analysis so if you have or how could i get please give me your hand. 1. Gamesa G80/2000 with hub height of 67m 2. Sany SE8220III with hub height of 70m Best regards Mengesha

Dear all, I am a student from Addis Ababa University, Ethiopia, and my Msc thesis is wind energy resource analysis using WAsP. Nobody those who have the knowledge by wind energy in this university so please help me these questions below. Q1. How can i predict turbine hub height? The wind power density normally increases with increasing hub height. This is because normally the decrease in power density due to the decrease in air density is insignificant compared to the increase in power density due to the increase wind speed. The increased annual energy production (due to increased Wind speed) not justifies the larger investment in a taller Tower. Q2. I have the data measured at 10m height study site and the calculated turbulence intensity at this height is 0.137. What is the formula can I use to determine the turbulence intensity at hub height after extrapolating this 10m wind speed to hub height? Turbulence intensity is very important to determine a wind turbine class to the site. Q3. I am trying to select wind turbines are based on the following criteria: Step 1: First look, by matching them site characteristics very close to wind turbine characteristics for all wind turbines. Step 2: By making comparisons of different wind turbines to the site such as the capacity factor, annual energy production and cost per KWh for each one, after this, choose the one which have higher capacity factor (CF) and annual energy production(AEP) , and less cost per KWh ($/KWh) will taken. So my question is: Comparison wind turbines as farm will difficult to me because it needs a lot time and messy. So to make simple, can I use one wind turbine generator from each type of wind turbines? From those who are full fill step1 and then going to step 2 to select one who have best wind turbine. Best regards, Mengesha

Dear Niels, Thank you very much for your help! It clears almost all but from an answer A4."WAsP contains a tool, the Air Density Calculator, which can help to estimate the air density at hub height at site" i got the result using air density calculator at an altitude=750m and average temp=27.02 0c above sea level.However, i want to calculate air density at 70m hub height, the hub height altitude will be 750+70= 820m but how could i determine average temperature( i have not data) corresponding to this altitude to calculator air density ? Best regards, Mengesha

Dear Niels, Thank you very much for your help! It clears almost all but from an answer A4."WAsP contains a tool, the Air Density Calculator, which can help to estimate the air density at hub height at site" i got the result using air density calculator at an altitude=750m and average temp=27.02 0c above sea level.However, i want to calculate air density at 70m hub height, the hub height altitude will be 750+70= 820m but how could i get average temperature( i have not data) corresponding to this altitude to calculator air density ? Best regards, Mengesha

Dear Niels, Thank you very much for your help! i have understood almost all but still i could not understand from A3,"A map should in general extend to at least 10 km (in all directions) from any mast or prediction site; if the mast and turbines are very high, the distance should be even larger (say, 100 times their height + 50%)" what do mean this and i need further clarification this statment"if the mast and turbines are very high, the distance should be even larger (say, 100 times their height + 50%)" Best regards, Mengesha

Dear all, My Master thesis work on “Wind Energy Resource Analysis: A case study of Aysha wind farm” using WAsP so that I need your help and an answer my questions. My questions are as follows with first describing of the site. No wind measurements have been taken at the proposed turbine site , but data have been collected at a 10m wind measurement. The distance between them is 9.5Km. The site roughness characteristics (some ruggedness) is completely different from the proposed turbine site characteristics (the farm is wide flat surface and sandy soil). Q1. WAsP calculates the data from the 10m wind measurement need to be analyzed to produce a wind atlas, and then the resulting wind atlas needs to be applied to the proposed turbine site to estimate the wind power. What is the effect of distance b/n them is 9.5km which is very far away from the proposed turbine and roughness characteristics of the 10m wind measurement and proposed turbine sites areas are completely diferent. How can I handle this to make the analysis is better? Q2. What do you mean by “impose site condition”? It is similar to method for Q1. Q3. Does WAsP can handle this triangle farm land size area (1/2 * W=30Km* H=37km) based on 10m wind measurement data? What is the size of the rectangular map should extend at minimum and maximum from the site of 10m wind measurement data? Q4. The calculated air density of this site at 10m height is 1.0809kg/m3 using an average temperature (27.02 oc) (this temperature data is taken from weather station at 2m height and 1.5km away from 10m wind measurement mast) and an altitude 750m). How can I extrapolate (estimate) the air density of the turbine’s hub height in this farm due to not having average temperature and an altitude at hub height to estimate air density? Q5. I have read from FAQ that WAsP assumes a logarithmic wind speed profile of the atmosphere, but how can I determine this site is stable, not stable or neutral? Thank you very much for your help! Mengesha