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Department of Electric
Power Engineering
Spring 2017
Adjustable Speed of
Synchronous Machines
for Hydropower
Applications
Supervisor:
Trond Toftevaag
Erik Hildre Bjørkhaug
MASTER THESIS
Background
Conventional hydro power plants use
synchronous machines/generators which are
directly connected to the grid, and can only run
at a constant speed. Variable speed operation
is possible by installing an AC/AC converter
between the grid and the machine, which
controls the stator frequency of the machine.
With variable speed, the power plants can be
operated with higher flexibility, such that the
active power can be regulated faster. This will
be important in the future power system, as the
production from
intermittent sources, such as wind and solar, is
going to increase. Variable speed operation
is most advantageous for pumped-storage
plants, since it is the only way of adjusting the
power during pumping. In this way, it can also
contribute to frequency stability of the grid.
The work includes realisation of a lab set up,
where an 8 kVA synchronous machine is fed
by a voltage source converter. It is planned to
perform tests in both motor and generator
mode.