The penetration of wind energy has been fast increasing during the last
decade across the world. In order to maintain and improve this growth
level, the EWEA introduced a wind research and development plan: the
European Wind Initiative (EWI). It aims, among others, at making onshore
and o shore power the most competitive energy source and reach wind en-
ergy penetration levels of 20% by 2020 and 50% by 2050 [7]. Because of
this growing penetration and given the high variability of wind speed pro-
les and the consequent energy shortage, regulations have been established
by the transmission system operators to de ne the parameters that must
be met by power plants connected to the electric network such as ride-thru
requirement and voltage regulation.
As mentioned in a EWEA report published in 2013 [6], one of the main
advantages of wind energy is its ability to contribute to the system opera-
tion and
exibility. Indeed, a variable-speed turbine equipped with power
converters has the ability to control the
ow of reactive power and inject it
into the grid in periods of voltage drop to contribute to voltage stabiliza-
tion. The possibility to capture a greater amount of energy by adapting the
turbine speed to the wind velocity is another important motivation behind
the growing share of variable-speed turbines (VSWT).
Among the di erent VSWT topologies, the DFIG system is of special
interest given its high energy e ciency and controllability but especially
because of the low power rating - and lower cost - of its power converters that only need to process one third of the rated turbine power [22]. Several
di erent control methods exist to control the active and reactive power
ows
through these converters. Some of these algorithms will be presented in this
report and implemented both in a software simulation and on a wind turbine
test bench. |