OFFERING MEMORANDUM Global Offering of up to ... - Nordex

which can turn the blade tip ‘‘out of the wind’’, acting as a type of aerodynamic brake similar to the
landing flaps of an airplane. The brakes in every wind turbine serve as emergency brakes and —
similarly to the hand brake in a car — to immobilize and secure the mechanical components.
Pitch regulation
In a wind turbine with pitch regulation, power regulation is achieved by mounting the rotor blades on
the hub so that they can be rotated around their longitudinal axis, in order to control their
aerodynamic properties and thus their capacity to capture energy according to the wind conditions.
When wind speeds (and thus the wind’s energy content) are low, the rotor blades can be turned ‘‘into
the wind’’ so that their angle of attack is maximized and, when a strong air flow creates too much
energy, they can be turned out of the wind. Pitch-regulated wind turbines are braked by allowing the
rotor blades to flap like flags in the wind.
In addition, the nominal rotational speed of the generator in wind turbines with pitch regulation can be
adjusted to the prevailing wind conditions. These turbines are therefore also described as variablespeed
wind turbines. In these units, an inverter is installed between the generator and the power grid,
which enables the generator to generate electricity at different frequencies.
The electronic controls in variable-speed wind turbines
In variable-speed wind turbines with pitch regulation, the electronic controls are the ‘‘brain’’ of the
turbine and adjust the angle of incidence of the rotor blades with the generator to keep them working
smoothly together. A key element of the Nordex Group’s expertise is comprised in its electronic
controls. The electronic controls measure the generator’s power output and, through the pitch
regulation adjust the angle of incidence of the rotor blades accordingly. If the generator’s power output
appears to be dropping, the rotor blades are turned slightly more into the wind, but if the generator’s
power output exceeds a pre-defined maximum limit, the electronic controls cause the pitch regulation
system to turn the rotor blades out of the wind.
The use of pitch regulation and the related control options ensures that the wind turbine produces the
maximum possible energy output from the wind in all wind conditions, taking into account not only
variable wind speeds, but also the energy density of the wind. The colder the air, i.e. the denser the air
surrounding the wind turbine, the higher the energy density. Consequently, cold wind blowing at the
same speed as a warm wind carries more kinetic energy than the warm wind. In order to obtain optimal
energy output, the angle of incidence of the rotor blades can be adjusted as necessary. The advantages
inherent in this method for the optimization of output, in turbines with a capacity of approximately 1.5
megawatts or more or in regions with particularly difficult wind conditions, outweigh the substantial
additional costs of-pitch regulated systems.
Other wind turbine components
Another component in the development of which the Nordex Group has considerable expertise is the
support system, i.e. the mast of the wind turbine. Strong forces act on the mast over the entire life of
the wind turbine; the nacelle of Nordex’s largest turbine, the N-80, weighs approximately 84 tonnes,
and the rotor weighs approximately 49 tonnes. The turbine’s mast has to withstand these forces and
provide a secure foundation to the nacelle and the rotor without swaying due to changes in wind force,
as this would result in the destruction of the turbine. The support systems used by the Nordex Group
are manufactured by various outside suppliers to the specifications of Nordex Energy GmbH.
The power generated by the wind turbine, usually at a voltage of 700 volts, is converted by a
transformer to a ‘‘medium’’ voltage of 10 to 30,000 volts—depending on the grid operator—and
supplied into the grid. When several wind turbines are operated together on a wind farm, the operator
must ensure that turning on or stopping the wind turbines does not cause electrical surges to be fed
into the utility’s power grid, which could cause damage when the electricity reaches power customers.
The Nordex Group’s Product Range
The Nordex Group’s product range covers the range of wind turbine types currently available on the
market, from the N-29 with 250 kW nominal output to the N-80 with 2,500 kW nominal output, which,
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