To calculate wind turbine power, you need to estimate two values: the available wind power and the efficiency of the wind turbine. Multiplying these two values produces an estimate of the output power of the wind turbine. Below you can find the whole procedure:
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Sweep area of the turbine
Before finding the wind power, you need to determine the swept area of the turbine according to the following equations:
For HAWT:
A = π * L²For VAWT:
A = D * Hwhere:
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Lis the blade length – the radius of the horizontal-axis turbine -
Dis the diameter -
His the turbine height
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Finding the efficiency of the turbine
You can find the total efficiency of the turbine as follows:
μ = (1 - kₘ) * (1 - kₑ) * (1 - ke,t) *(1 - kt) * (1 - kw) * Cₚwhere:
Cₚis the turbine efficiency. It must be lower than the Betz limit (59.3%), and is typically between 30-40%kware the wake losses due to neighboring turbines and the terrain topography, typically 3-10%kₘare the mechanical losses of the blades and gearbox, typically 0-0.3%kₑare the electrical losses of the turbine, typically 1-1.5%ke,tare the electrical losses of transmission to grid, typically 3-10%ktis the percentage of time out of order due to failure or maintenance, typically 2-3%μis the real efficiency
Efficiency is usually expressed as a percentage, but you input it into the formula as a fraction (for example, 30% = 0.3).
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Calculate the available wind power
Once you know the sweep area, you can find the available wind power according to this formula:
Pwind = 0.5 * ρ * v³ * Awhere:
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Ais the sweep area -
ρis the air density, assumed to be 1.225 kg/m³ by default (you can change it in advanced mode) -
vis the wind speed – the typical usable range is approximately 3-25 m/s -
Pwindis the available wind power
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Calculating the output power
To find the wind turbine power, simply multiply the efficiency by the wind power available:
Poutput = μ * Pwind
