THESIS
2022
1 online resource (xviii, 227 pages) : illustrations (some color)
Abstract
In the recent decade, the world faces the energy crisis and global warming phenomena that
seriously affect the lives of future generations. Renewable energy resources are one of the possible
solutions to address these challenges because they are environmentally friendly and affordable.
Among all the renewable energy resources, wind energy is one of the most notable resources due
to its availability. Horizontal axis wind turbines are the most common type of wind turbine to
convert the kinetic energy of the wind to electrical power. To reduce the maintenance cost of the
wind turbine during its life span, it is necessary to mitigate the vibration loads. The power control
of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the
tower and the blad...[
Read more ]
In the recent decade, the world faces the energy crisis and global warming phenomena that
seriously affect the lives of future generations. Renewable energy resources are one of the possible
solutions to address these challenges because they are environmentally friendly and affordable.
Among all the renewable energy resources, wind energy is one of the most notable resources due
to its availability. Horizontal axis wind turbines are the most common type of wind turbine to
convert the kinetic energy of the wind to electrical power. To reduce the maintenance cost of the
wind turbine during its life span, it is necessary to mitigate the vibration loads. The power control
of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the
tower and the blades. In this thesis, we are going to consider both the power control and vibration
load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully
coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behavior of
the blades and tower and is validated by experiment results, comparing the time history data with
the FAST (Fatigue, Aerodynamics, Structures, and Turbulence ) code which is developed by
NREL (National Renewable Energy Lab in the United States). The blades and the tower are
modelled as flexible structures that can vibrate in two perpendicular directions. The aeroelastic
model is used in the next parts of the research. Effective wind velocity (EWV) is the necessary
part of each control system. In the next, to estimate EWV, a novel hybrid approach was developed
by combining a sliding mode observer and an adaptive neural fuzzy inference system (ANFIS).
Novel sensorless control algorithms are developed based on the super twisting sliding mode
control theory and sliding mode observer for disturbance rejection (by using EWV as an input). In
region 2 (the wind speed is between the cut-in and rated wind velocity), the novel sensorless
control algorithm increased the power coefficient in comparison to the indirect speed control (ISC) approach which is the conventional method in the industry. In region 3 (the wind speed is between
the rated and cut-out speed), at first, pitch sensitivity is estimated by using a proper ANFIS system.
The rotor speed, pitch angle, and estimated EWV are inputs and the pitch sensitivity is the output.
The designed novel pitch control performance is compared with the gain scheduled PI (GPI)
method which is the conventional approach in this region. The simulation results demonstrate that
the flapwise blade displacement is reduced significantly. We also consider the problem of lateral
active vibration control of the tower and power control in region 3. We demonstrated a way how
to solve the trade-off problem of active lateral vibration control by using the generator torque and
power control in region 3. This novel approach is based on an intelligence fuzzy system to reduce
lateral vibration of the tower and a suitable pitch control strategy for power regulation.
Post a Comment