| Abstract |
Frequency converters are used in wind turbines
because they make it possible to apply the variable-speed
concept. They also make it possible for wind farm to become
active element in the power system. The traditional frequency
converter is a back-to-back connected two-level converter, in
which the output voltage has two possible values. However, the
output voltage is smoother with a three-level converter, where
output voltage has three possible values. This results in smaller
harmonics, but on the other hand it has more components and is
more complex to control. In this paper we study the different
three-level converter topologies and make a cost and power loss
comparison between the two-level and three-level converters
assuming the same input voltage and switching frequency. The
study is a part of a course called “Nordic PhD Course on Wind
Power” which was held in Smöla, Norway at June 5th – 11th 2005. |
