How to Calculate P75, P90 & P95 Values for AEP Prediction in a Wind Power Plant

Tri_anand,

Mostly it is based on meterological data for the particular site, to give the % distribution of wind speeds for a year. This is then input into a spreadsheet or other program in which the turbine's power output is entered for each wind speed. The result of this calculation is the AEP or annual energy production. Depending on the reliability of the original data, turbine height, turbine design, the variability in the weather, and maintenance or breakdown history, you will have a likelihood or probability that the actual energy output will be less than the calculated AEP. Bankers like to look at returns so the probability is expressed in the opposite terms--the probability of the AEP being too low. This probability is your Pxx, where xx is some number for the percent probability that the calculated (predicted) output will be exceeded by the actual.

I have not done these calculations myself, but I suggest a search on the relevant terms. One fairly simple report I came across was at: http://www.dewi.de/dewi/fileadmin/pdf/publications/Magazin_28/07.pdf. Another site was a consultant in this area: http://www.kema.com/services/consulting/efficiency/project-development/wind-resource-modeling.aspx. Another company's brochure is at: http://eapcwindenergy.com/eapcwind-brochure-200907.pdf.

Hope this helps with information you may not have had already. --John M.