The planning tool for district energy systems

# Wind power calculation

With nPro power generation profiles for wind turbines in hourly resolution can be generated. On this page it is documented how these are calculated.

## How are wind power profiles calculated?

In nPro, the wind speed at hub height of the wind turbine is calculated in a first step. For this purpose, the power law according to Hellmann is used: $$w_\mathrm{hub} = w_\mathrm{ref} \left(\frac{h_\mathrm{hub}}{h_\mathrm{ref}}\right)^a$$ Here, $$w_\mathrm{hub}$$ is the wind speed at hub height, $$w_\mathrm{ref}$$ the measured wind speed, $$h_\mathrm{hub}$$ the hub height, $$h_\mathrm{ref}$$ the reference height at which the wind speed measurement took place, and $$a$$ the Hellmann coefficient. In a second step, the generation power of the turbine is calculated with power curves from manufacturer data. In Table 1 the power curve of the wind turbine Enercon E141 is illustrated.

The nPro tool calculates for different wind turbine models the power generation profile with hourly resolution. Figure 1: Annual energy yield of an ENERCON E115-EP3 turbine for the two size classes 4.2 MW and 2.99 MW.
Table 1: Power curve of the wind turbine Enercon E141.
Wind speed at hub height Power generation
0 m/s 0 kW
1 m/s 0 kW
2 m/s 22 kW
3 m/s 104 kW
4 m/s 260 kW
5 m/s 523 kW
6 m/s 920 kW
7 m/s 1471 kW
8 m/s 2151 kW
9 m/s 2867 kW
10 m/s 3481 kW
11 m/s 3903 kW
12 m/s 4119 kW
13 m/s 4196 kW
14 m/s 4200 kW
... 4200 kW
25 m/s 4200 kW
25.1 m/s 0 kW

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