Modeling & simulation of hydraulic pitch actuator for wind turbine.
1. Modeling & Simulation of hydraulic pitch actuator for wind turbine
Name: Md Ahmed Sanuar Hossain (李太原) Student ID: 2017590037
Modeling & Simulation of hydraulic pitch actuator for wind turbine.
Before starting the question, you must read at least 30 references
The Origin and Significance of Topic Selection
Pitch control is the technology used to operate and control the angle of the blades in a wind
turbine. The system is in general either made up by electric motors and gears, or hydraulic
cylinders and a power supply system. Pitch control is important for the aerodynamic
efficiency of wind turbine influencing the energy capture, pitch angle being an Important
parameter by its influence on the angle of attack of the wind. This kind of control is also
important in order to protect the turbine in the case of high values of the wind speed
Reducing the extreme loads. In many cases the system used to change pitch is a hydraulic
System. Considering the tendencies in using hydraulic systems in wind turbines, some
research Directions resulted from reviewed scientific articles. In the case of high-power
wind turbines, the load on the blade being important, the rotation of the blades around their
own axes in order to change the pitch angle supposes great acting forces. Hydraulic
systems provide them in Reduce size equipment. The blade rotation may be controlled
simultaneously, in the case of collective pitch control, or separately for each one of the
blades, in the case of individual control of the blades. The pitch system is a closed loop
drive system. The turbine main controller calculates the required pitch angle from a set of
conditions, such as wind speed, generator speed and power production. The required pitch
angle is transferred to the pitch system as a set point. If the actual angle is NOT the same as
the set point, the system will direct power to the fluid to the cylinder in order to make the
actuator move the blade to the required angle.
2. Modeling & Simulation of hydraulic pitch actuator for wind turbine
Literature review (the current level and problems of the research in this paper)
Hydraulic systems for pitch control
Modern wind turbines use active pitch control, with electrical or hydraulic pitch actuators.
Comparing with electrical motor driving system, hydraulic driving system not only
replaces the gear sets but also enhance the robustness. Hydraulic devices have also some
already known difficulties such as lower efficiency and higher nonlinearity problems which
should not be neglected. A study was developed regarding leakage estimation for a wind
turbine hydraulic pitching system considering a time-varying load on hydraulic system.
Leakage may reduce the effective stiffness and efficiency and these are the reasons it is
considered a critical fault for hydraulic systems. The structure chosen for that has classical
components used in similar cases: a positive displacement pump, a servo valve or a
proportional directional valve, a double acting single rod cylinder, a relief valve and a
check. The force exerted at the cylinder rod produces the pitching motion with a slider-
crank mechanism which connects the rod of cylinder to the pitching blade shaft through a
rigid bar. In the last decade of nineteenth century was investigated an electro-hydraulic
actuator by using gear pump and electromotor. This kind of system was revealed to be a
high response and high energy efficiency hydraulic system. It involves an electric
hydrostatic driven system with an AC servomotor and a constant displacement internal gear
pump for power-saving. A servo system structure with an AC servo motor and a constant
displacement hydraulic piston pump realizes both high response and high energy
3. Modeling & Simulation of hydraulic pitch actuator for wind turbine
The research developed in effects of an adaptive fuzzy controller with self-tuning fuzzy
Sliding-mode compensation on pitch control performance. Hydraulic systems used in wind
turbines are difficult to mathematical modeling due to the nonlinearities and it is necessary
to simplify or linearize the equations in order to obtain a model-based controller. The
experimental results clarify that the pitch control controlled by self-organizing fuzzy
sliding mode control can perform better than that controlled by fuzzy sliding mode control.
This structure is considered for collective pitch control in the test rig. In hydraulic pitching
systems have slower response, but bear much larger stiffness, little backlash and higher
reliability. Hydraulic systems are considered suitable in the case of high values of
aerodynamic loads assuming that their failure cover an important portion among different
factors of wind turbine failure. A statistical study on Swedish wind farm during 2000 to
2004 found that 13.3% of failure events during 2000 to 2004 were due to the hydraulic
system. In order to prevent the failure of wind turbine must be prevented the failure of
hydraulic pitching system The functioning of the hydraulic system depends on the effective
bulk modulus of the fluid and can be greatly reduced due to a small amount of air
contamination. Reduction of fluid bulk modulus leads to the reduction of plant bandwidth,
and thus reducing the stability robustness of the corresponding closed loop system. Similar
issue occurs for significant leakage in the hydraulic system.
Liniger propose a hydraulic system diagram for individual pitch control including an
Accumulator in two possible configurations. Considering that the accumulator is a
Component which has a high failure rate, especially through gas leakage, in the paper was
proposed an Estimation method in order to detect this specific problem.
Modeling the pitch control system has an important role in the development of systems,
Helps us to identify the possible abnormalities which can appear in the whole system,
between certain parameters. A study, conducted by researchers from Université Libre de
Bruxelles considered the hydraulic circuit introduced a nonlinear mathematical model for
certain situations Under normal operating conditions and under malfunctioning of a
hydraulic actuator, MATLAB/SIMULINK wind turbine simulator. It was noted that a linear
model is enough for Situations in which the system is operating in normal conditions,
however, when it comes to the study of the diagnosis of fault, it is recommended to use a
nonlinear model. In study of the thermo-dynamical processes involved in a hydraulic
Accumulator during operation, and how they affect the energy efficiency of the component.
4. Modeling & Simulation of hydraulic pitch actuator for wind turbine
3. Main scientific and technical issues to be solved in this paper
1. Review relevant literature and gain in-depth understanding of the research ideas and
methods of the project.
2. Design of hydraulic Pitch actuator in Solid works software for investigation of its
3. Design of pitch controller through PID and Fuzzy Controlling system in Mat
5. Modeling & Simulation of hydraulic pitch actuator for wind turbine
4. Main research contents and methods, experimental scheme and schedule
The specific content of this topic is as follows
1. Hydraulic Pitch Actuator: The present invention relates to a hydraulic pitch system
for pitching a blade of a wind turbine having a hub by means of a hydraulic fluid. The
system comprises at least one hydraulic cylinder for adjusting a pitch angle of the
blade, the hydraulic cylinder comprising a pitch piston movable in the hydraulic
cylinder, and a first port and a second port arranged on each side of the pitch piston,
and an accumulator hydraulically connected to the cylinder. The system further
comprises a pitch safety system adapted to maintain the blade in a predetermined
pitch angle when a person is entering the hub of the wind turbine for service and/or
maintenance, the pitch safety system comprising a first valve which by activation
releases a pressure in the hydraulic pitch system by draining off the accumulator for
the hydraulic fluid until the pressure has reached a predetermined pressure level.
According to the structure of the part, using designing software solid works, to
constantly fine-tuning the angle of the blades to the wind to optimize the wind
turbine’s energy production.
Structure of the hydraulic blade pitches system.
6. Modeling & Simulation of hydraulic pitch actuator for wind turbine
2. Pitch Controller: Using a good pitch controller (PC) which will tune the attack angle
of a wind turbine rotor blade into or out of the wind. A mathematical model of wind
turbine (pitch control system) will develop with Fuzzy Controller and conventional
PID Controller. After comparing the proposed strategy, the simulation results will
show which controller has the optimum response as it controls the pitch system as
well as the disturbances and uncertain factors associated with the system.
a. PID controller design
b. Improved Fuzzy Logic Controller (FLC)
PID controller design
Improved Fuzzy Logic Controller (FLC)
7. Modeling & Simulation of hydraulic pitch actuator for wind turbine
3. Anemometer and wind vane: Anemometer Measures the wind speed and transmits
wind speed data to the controller. The controller is installed in case the wind speeds
reach an undesired speed, the anemometer can instruct the controller to use the brake
and stop the rotating blades. The controller is also used to help start spinning the
blades and rotor in low wind speeds. The wind vane is an instrument that measures
the direction of the wind. The wind vane is important for up-wind turbines that need
to be facing the wind in order to operate properly. The yaw drives in the mechanism
that receives data from the wind vane and instructs the wind turbine to rotate to be
facing the wind.
8. Modeling & Simulation of hydraulic pitch actuator for wind turbine
4. Sensors: some sensors will be used for maximum efficiency such as pressure sensor,
pressure relay, temperature sensor, level switch.
Still I am doing some experiments. I am hope so I will get enough wind speed from the
hydraulic pitch actuator. I would easily generate electricity from wind turbine. It is important
to analyses the PID and Fuzzy Logic control law and to state the error and the gain.
1. 2018.8-2018.10: Check the relevant literature, learn Mat lab/Simulink and solid works
software, and complete the opening report.
2. 2018.11-2019.2: 2. Study hydraulic pitch actuator related papers to improve to harvesting
maximum wind speed.
3. 2019.3-2019.6: Looking for a new solution to solve the problem of the current actuator
sealing system. Improving the sensors system through PID and Fuzzy controlling system
sync with sensors and anemometer.
4. 2019.7-2019.10: Exploring the effect of hydraulic pitch actuator controlled by sensors.
5. 2019.10-2019.12: Organize the research results and write the first draft of the dissertation.
6. 2020.1-2020.6: Modify and improve the large thesis.
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9. Modeling & Simulation of hydraulic pitch actuator for wind turbine
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 STRUCTURAL PITCH FOR A PITCH-TO-VANE CONTROLLED WIND
TURBINE ROTOR DAMPBLADE project, task 3.4: .Design application,sensitivity
analysis and aeroelastic tailoring.