Environmental Engineering Reference
In-Depth Information
only the rotor and the nacelle assembly, but also the tower and the floating plat-
form. However, the effects depend on how the rotor imbalance is built up, the
operating condition, and the fault magnitude.
This chapter is organized as follows: Sect.
11.2
describes the considered ref-
erence floating wind turbine model used in simulation along with its operating
region and the implemented controller, in addition to the considered pitch system
model. The sensor and actuator faults of the pitch system are presented in
Sect.
11.3
. Section
11.4
goes through the simulation setup, the environmental
conditions (ECs) in addition to the addressed fault scenarios. The obtained sim-
ulation results are discussed and analyzed in Sect.
11.5
. Finally, Sect.
11.6
states
the final conclusion of this chapter.
11.2 Wind Turbine
11.2.1 Reference Wind Turbine
The NREL offshore 5-MW baseline turbine [
13
] model mounted on the barge
platform is used as a reference wind turbine (RWT). The turbine is a fictitious
5-MW machine with its properties based on a collection of existing wind turbines
of similar rating since not all turbine properties are published by manufacturers.
The barge is a rectangular platform designed to be a cost effective and easy to
install platform suitable for shallow water. It utilizes the buoyancy due to its large
water-plane area to maintain stability. Since most of the platform is above the
water, it is very sensitive to incident waves. The main properties of this turbine and
the barge platform are listed in Table
11.1
.
11.2.2 Regions of Operation
The variable-pitch variable-speed wind turbine operates typically in two different
regions, namely the full load region where the wind speed is above its rated value,
and the partial load region where the wind speed is less than its rated value
(Fig.
11.4
). In the full load region (known also as the above-rated region), the wind
has enough energy to run the turbine at its rated rotor speed, and the main task of
the controller is to adapt the aerodynamic efficiency of the rotor by pitching the
blades into or out of the wind in order to keep the rotor speed at its rated value. On
the contrary, the maximum aerodynamic efficiency is maintained in the partial load
region (also known as the under-rated region) where the wind speed is less than its
rated value, and the controller task is to follow the maximum power production by
changing the rotor speed and consequently the generator torque. The partial load
region could also be divided into subregions in order to handle the transition at the
cut-in wind speed where the rotor should be accelerated till it reaches the power
