sin αst

7
Generator and electrical system
The present chapter provides an overview of several generator options and explains the
selection made for the wind turbine design. Since the main focus of this project thesis in on
mechanical and aerodynamic design, the generator is only treated to a certain extent. The
chapter also contains a proposal for the components that should be included in the electri-
cal system.
7.1 Generator
The generator may be categorised as one of the key components in electricity producing
wind turbines. Its basic function is to convert mechanical energy into electrical energy by
means of a rotating magnetic field, which induces a voltage in the stator windings of the
generator. The generator has a high influence on the performance of the wind turbine and
its characteristics are important to the design of the wind turbine rotor.
Distinction is often made between the terms alternator and generator, where the first
commonly refers to a machine producing alternating current (AC) and the latter refers to a
machine producing direct current (DC). This project thesis does not make distinction be-
tween the two terms and denotes both types of machines as generators.
The most suitable type of generator is selected based on criteria such as simplicity, produ-
cability/availability and its impact on the rest of the wind turbine design.
Table 7.1 provides the results of a survey of different generator options that may be used
in small scale wind turbines. The listed technical properties, advantages and disadvantages
are subjective and based on assessments and information gathered during the survey.
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