sin αst

GENERATOR AND ELECTRICAL SYSTEM
In practice the generator is expected to be designed with a linear characteristic as shown
on figure 7.3.
Figure 7.3: Linear characteristic of the generator
The intended generator is designed to cut in at 250 rpm, meaning that the rectified DC
voltage at this angular velocity is high enough to produce power (see section 7.2 for more
information). The efficiency of the generator will vary as a function of the rotational speed,
but for the purpose of power calculations the total generator efficiency �g is assumed to
have a constant value of 45% [61]. The generator efficiency also takes into account any
losses in the electrical system.
7.2 Electrical system
Design of the electrical system is beyond the limits of this project thesis. A proposal of the
components that should be included in the system is however made, as several of these are
required to comply with various requirements of IEC 61400-2 and of the requirement list.
Figure 7.4 provides a schematic overview of the complete electrical system from the gen-
erator to the battery bank.
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