978-1-5386-7850-3/19/$31.00 ©2019 IEEE
Advanced Control of a DFIG-based Wind Power
Plant for Frequency Regulation
Mohamed Nadour*, Ahmed Essadki, Mohammed
Fdaili
Research Centre of Engineering and Health Sciences and
Technologies (STIS), High Normal School of Technical
Education (ENSET), Mohammed V University.
Rabat, Morocco
mohamed.nadour@um5s.net.ma,
mohamed.fdaili@um5s.net.ma
Tamou Nasser
Research Centre of Engineering and Health Sciences and
Technologies (STIS), Higher National School of Computer
Science and Systems Analysis (ENSIAS), Mohammed V
University
Rabat, Morocco.
tamounasser@gmail.com
Abstract—the expansion of renewable power penetration in the
power system has given rise to many concerns in terms of
frequency stability. Since unlike the conventional synchronous
generators, these intermittent energy sources do not inherently
undertake frequency regulation. For instance, The Doubly-fed
induction generator (DFIG) based wind power plants have a
destitute response to frequency deviations, being that its rotational
speed is almost totally disassociated from the grid frequency.
Another point is that significant wind power penetration leads to
the retirement of many conventional power plant. Which lowers
the power system’s total inertia and the power reserves that are
normally needed to preserve the frequency within an adequate
range of variation. Therefore, this paper proposes an advanced
control strategy that allows of the DFIG based wind energy
conversion system to provide, at the event of frequency excursion,
an inertial support for the power system through a simultaneous
use of the kinetic energy reserved in the turbine rotating masses
and a portion of the energy reserved in the DC-link capacitor. A
case of four synchronous generators SGs connected with a DFIG
bases wind farm WF considering a sudden frequency disturbance
has been studied using Matlab/Simulink to validate the capability
of the suggested control strategy.
Keywords- Wind Turbine; DFIG; Frequency control; MPPT;
Backstepping; DC-link.
I.
I
NTRODUCTION
In last few decades, thanks to the recent development in the
field of power electronics, machines and systems control, wind
power generation has experienced a significant growth
compared to others renewables energy conversions systems.
However, as this type of power generation continue flourishing
worldwide and as we keep on increasing its power penetration
in the system, the electrical network will have to face multiple
stability challenges, such as frequency excursions. Since, unlike
the conventional synchronous generators that are naturally
designed to provide a response to frequency deviations (a
release or absorption of kinetic energy) [1]. The wind energy
conversion system does not possess this inherited response to
help the system in arresting the frequency decay, being that its
rotational speed is almost totally dissociated from the frequency
of the network by the presence of the power electronic interface
that is normally controlled only to ensure a maximum wind
power extraction. Moreover, an increase of the wind power
penetration will minimize the total equivalent inertia of the
power system by leading to the withdrawal of more and more
traditional generation plants. Which actually present the units
that are taking almost all the responsibility in maintaining the
frequency within an acceptable range of a very small variation.
This problem is recognized and significantly discussed over
the past few years. Some works have proposed the utilization of
the turbine kinetic energy to support the system in frequency
regulation during transient [2]. While others, have suggested
operating the wind turbine following a de-loaded operation
characteristic instead of the maximum power point tracking
MPPT characteristic [3]. In order to create a certain power
reserve, using either the pitch or the mechanical speed control,
which can automatically be activated to support the system right
after the detection of a frequency deviation. However, this
strategy lowers noticeably the energy yield, which may require
monetary compensation for the wind power plant owner.
Moreover, [4] have proposed a coordinated control strategy
using both of the previous methods to enhance the WT response
to frequency excursions.
This paper, proposes an advanced (rotor and grid side RSC
GSC converters) control strategies of the DFIG bases wind
turbine. Allowing the system to provide an artificial inertial
support to the power system at the event of a frequency
deviation, by a simultaneous release of the kinetic energy store
in the turbine rotating masses and a portion of the energy stored
in the DC-link capacitor with respect to some system stability
concerns. The case of four synchronous generation units
(representing the electrical grid) connected to a DFIG based
wind farm considering a sudden change in the load, hence,
frequency disturbance is studied. The simulation results in
Matlab/Simulink environment show the validity of the
suggested control strategy in terms of tracking behavior and