Your name Book report
Danny Doan
IntroductionGive an overview of the book, indicating what the
focus of your book report will be. You can replace the picture on
the right with a picture of the cover of the book. Simulation and
Control of Wind Turbine using Hydrostatic Drive TrainAuthor: A.
Nikranjbar1, A. Nazarian Sharbabaki1- Islamic Azad University/
Faculty of Engineering, Karaj, Iran. Email: [email protected]
(Corresponding author)2- Malek-Ashtar University of
Technology/Mech. & Aero. Dep., Isfahan, Iran. Email:
[email protected]
AuthorOutline the authors life, focusing on the timeframe that
includes the writing of this book.Main charactersCharacter
OneDescribe this character.
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Information aubout the paperReceived March 2012 /Revised Sept.
2012 /Accepted Dec. 2012
ThemesDescribe the theme(s) of the book.EvaluationMake your main
points here. Evaluate the book. Draw your conclusions.
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ARTICLE
AABSTRACTI. Study about abstract1. PurposeIn paper with the
demands to obtain energy from renewable energy resources,
utilization of the wind turbines to convert the wind energy into
the desired usable form with maximum efficiency has been faced with
ever increasing research efforts. In this study taken a different
approach with conventional systems, wind turbine with hydrostatic
power train system is considered.2. Research
Strategy/DesignHydrostatic power train system characterized with
high power and torque transmission along with significant
efficiency, capable of reliably controlling the performance of the
system, and persistent hydraulic components, has been replaced with
the conventional mechanical power train system between the vane and
electric generator.3. FingdingTo explain the performance of the
proposed system, a mathematical model of wind turbine with variable
speed hydrostatic transmission in the MATLA/SIMULINK software has
been established and the system control algorithm is presented.4.
ConlusionBased on the detailed mathematical model and using the
information of hydraulic equipments from famous vendors and
manufacturers to make the results ever realistic, simulation
results showing the great performance compared to the today's
conventional wind turbines.
BKEYWORDS: Wind turbines, Hydrostatic power train, Wind turbine
simulation and control.
CINTRODUCTIONII. Research Problem/Purpose1. What problem is
being studied?Resounding to the industrial and technological
challenge to introduce the cost-effective, reliable wind energy
conversion solutions, considerable set of research efforts have
been started.2. Is there a stated purpose or set of study goals?In
conventional types, the wind passing over the blades exerting a
turning force. The rotating blades turn a shaft inside the nacelle,
which goes into a gearbox. The gearbox increases the rotation speed
for the generator, which uses magnetic fields to convert the
rotational energy into electrical energy. The power output goes to
a transformer, which converts the electricity from the generator to
the right voltage for the distribution system [2]. To overcome the
drawbacks of the traditional method, specifically to eliminate the
need to gearbox, the new concept of hydrostatic transmission (HST),
which is characterized employing the application of continuously
variable hydrostatic transmissions for wind turbines, is
introduced.The author eliminate: The need to gearbox/The need for
power electronicsIII. Background Literature1. What kind of articles
are described?[1]
http://en.wikipedia.org/wiki/History_of_wind_power #
Early_Middle_Ages. [2] T. Burton, N. Jenkins, Sharpe D, and E.
Bossanyi, Wind energy handbook, 2nd ed., John Wiley & Sons:
West Sussex, England, pp. 2-7, 2011. [3] B. Bohlmann, Hydrostatic
transmission for wind power,The National science foundation
engineering research center, College of Science and Eng., Dep. of
Mech. Eng., University of Minnesota. [4] J. Schmitz, N. Vatheuer,
and H. Murrenhoff, Hydrostatic drive train in wind energy plants,
RWTH Aachen University, IFAS Aachen, Germany. [5] X. Guo, X. J.
Jibin, Z. Peng, and C. Jing, Numerical simulation and dynamic
characteristics of secondary controlled hydrostatic drive,presented
at theIEEE International Conf. on Mechatronics and Automation,
Harbin, China, Aug. 58, 2007.[6] P. Srensen, A. D. Hansen, and P.
A. C. Rosas, Wind models for simulation of power fluctuations from
wind farms, Journal of Wind Engineering, Vol. 90, pp. 13811402,
2002. [7] G. Marsaglia, and W. W. Tsang, The ziggurat method for
generating random variables, Journal of Statistical Software, Vol.
5, No. 8, pp.1-7, 2000. [8] E, Muljadi, and C. P. Butterfield,
Pitch-Controlled Variable-Speed Wind Turbine Generation, IEEE
Trans. on Industry Applications, Vol. 37, pp. 240-246, 2000. [9] B.
Chitti Babu, and K. B. Mohanty, Doubly-Fed induction generator for
variable speed wind energy conversion systems- modeling &
simulation, International Journal of Computer and Electrical
Engineering,Vol. 2, pp. 141-147, 2010. [10] S. Heier, Grid
Integration of Wind Energy Conversion Systems,John Wiley & Sons
Ltd. 1998. [11] K. Tan, S. Islam, Optimum control strategies in
energy conversion of PMSG wind turbine system without mechanical
sensors, IEE transactions on energy conversion,Vol. 19, No. 2, pp.
392399, 2004. [12] F. A., Rassul Abbas, and M. A., Abdulsada,
Simulation of wind-turbine speed control by matlab, International
Journal of Computer and Electrical Engineering, Vol. 2, pp.
1793-8163, 2010. [13]
www.Mathworks.com/Matlab/Simulink/SimHydraulic help. [14] J.
Johnson, Introduction to fluid power, 1nd ed.,Cengage Learning,
2002.By replacing the gearbox of traditional wind turbines with a
continuously variable hydrostatic transmission (HST), the rotor
speed could be controlled independent of the generator
speed.Sim-Hydraulics is a block package under the Sim- scape in
Simulink which is used to model up a hydro- static drive train
system. Also used from Sim-Mechanic blocks (another block package
under Simscape). The proposed model has been developed in Matlab-
Simulink environment, Sim-Hyhraulics and Sim- Driveline tool boxes
is used simultaneously to optimal using of rapid prototyping
facility.
2. Can you tell from the literature why the authors are doing
this study?Thus, by replacing the gearbox in a wind turbine with an
HST, the reliability of the machine could be increased.This
research aims to present a fixed speed wind turbine simulation with
constant blade pitch angle and a typical variable speed hydrostatic
system as a drive train. For the purpose of this research a
specific drive train system with a secondary control unit in
hydrostatic transmissions with a variable- displacement motor is
developed [5]. The secondary control unit is used to control hydro
motor swash plate movements and consequently the motor
instantaneous displace- ment, output shaft angular velocity and
amount of entered torque to the generator.3. Is the study
important?Yes, it is. Because in this study taken a different
approach with conventional systems which help decrease the high
cost and increase the effection.IV. Research question/Hypothesis1.
Does the research question (hypothesis) follow logical from the
literature review? Yes, it does.2. Is there a clear rationable for
the hypothesis?This new concept also provides the generators
rotational speed to be matched exactly to the frequency of the
power network by continuously varying the transmission ratio, thus
omitting the need for frequency converters and providing higher
current quality. At the same time, the rotational speed of the wind
turbine can be controlled. Positive side effects are the good
damping characteristics of the hydraulic drive train as well as the
high power to weight ratio which results in a significantly reduced
weight of the nacelle. Due to a modular design the transmission can
also be adapted to a wide power range by switching off several
parts of the system and virtually maintenance-free, which
drastically reduces the operating and maintenance costs with ease
of access to critical components [4].
DMAIN IDEA
EMETHODV. If sampling was used/identify (Nu c s dng phng php ly
mu)1. Who was studied?2. How were they selected?3. Name the
sampling strategy?4. Is the sample appropriate; would you suspect
that any bias was introduced into the study because of the sampling
strategy?
VI. Procedures/established methoda. WIND MODEL[6] P. Srensen, A.
D. Hansen, and P. A. C. Rosas, Wind models for simulation of power
fluctuations from wind farms, Journal of Wind Engineering, Vol. 90,
pp. 13811402, 2002. 1. What is the implementation procedure?The
wind speed is calculated as an average value of the fixed-point
wind speed over the whole rotor, and it takes the tower shadow and
the rotational turbulences into account.2. What ideas were used
into the study?Wind models for simulation of power fluctuations
from wind farms.3. Is the study design appropriate for answering
the question?
[7] G. Marsaglia, and W. W. Tsang, The ziggurat method for
generating random variables, Journal of Statistical Software, Vol.
5, No. 8, pp.1-7, 2000. 1. What is the implementation procedure?A
main component in this model is the normally distributed white
noise generator. Therefore, in order to obtain the same wind time
series in all considered simulation tools used in the Simulation
Platform some investigations have been done. It has been found that
the built in white noise generator from different simulation tools
uses a different algorithm and thus a different wind time series is
obtained. A new normally distributed white noise generator has been
implemented using a 'C' S-Function based on the Ziggurat Algorithm
developed by G. Marsaglia [7]. The general structure of wind
Simulink model is shown in Fig. 2.
2. What ideas were used into the study?The ziggurat method for
generating random variables3. Is the study design appropriate for
answering the question?A wind time series for 50 sec with 0.05 sec
sample time, an average wind speed of 9 (m/sec) and (16 m/sec) and
12% turbulence intensity has been generated for the model as shown
in Fig. 3.
b. WIND TURBINE ROTOR MODEL[8] E, Muljadi, and C. P.
Butterfield, Pitch-Controlled Variable-Speed Wind Turbine
Generation, IEEE Trans. on Industry Applications, Vol. 37, pp.
240-246, 2000. 1. What is the implementation procedure?Models for
the power producing capabilities of a wind turbine rotor have been
previously developed [8]. The block diagram of the wind turbine
rotor is presented in Fig. 4.
According to (1), the output mechanical power of the wind
turbine (PT) is given by the usual cube law equation [9].
Where, PT is mechanical output power of the turbine (W), CP is
the power coefficient, is the air density (kg/m3), A is the wind
turbine rotor swept area (m2) and V is the wind speed (m/s).
Equation (2) present a generic equation i.e. used to model up CP.
This equation, based on the modeling turbine characteristics of
[10] is presented below.
Where is tip speed ratio ( is shown as (4)), is blade pitch
angle and the coefficients C1to C6 are; C1=0.5176, C2=116, C3=0.4,
C4=5, C5= 21 and C6=0.0068. The power coefficient for proposed
model of wind turbine rotor with various pitch angles versus tip
speed ratio is presented in Fig. 5. According to shown figure, the
maximum value of Cp (CPmax= 0.48) is achieved for =0 degree and for
=8.1. This particular value of is defined as the nominal value
(nom). Some relationship between CP, various and various wind
speeds are presented in [11], [12].
Where T is the mechanical angular velocity of the generator
(rad/s), R is the radius of the rotor (m) and V is wind speed
(m/s).
The wind turbine power characteristics for zero pitch angle (=0)
with average wind speed of 12 (m/s) and different values of the
pitch angle are illustrated as Fig. 6.
The wind turbine rotor has been developed in Matlab-Simulink
simulator software. The simulink model is presented in Fig. 7.
2. What ideas were used into the study?Pitch-Controlled
Variable-Speed Wind Turbine Generation3. Is the study design
appropriate for answering the question?Fig. 5. Power coefficient
versus tip speed ratio with various pitch angles Fig. 6. The
turbine power characteristics for zero pitch angle Fig. 7. The
Simulink model for the fixed speed wind turbine rotor c.
HYDROSTATIC DRIVE TRAIN SYSTEMIn this paper, the system
demonstrates usage of the so-called ''secondary control'' in
hydrostatic transmissions with a variable-displacement motor. The
drive train system consists of a hydrostatic transmission built of
a pressure compensated variable-displacement pump, a variable-
displacement motor, a fixeddisplacement pump as a booster pump,
pressure relief valves, check valves, the secondary control unit
and so on. The block diagram of closed circuit hydrostatic
transmition system is presented in Fig. 8.
4.1. Hydraulic Pump[13]
www.Mathworks.com/Matlab/Simulink/SimHydraulic help. 1. What is the
implementation procedure?A variable displacement
pressure-compensated pump has been used in hydrostatic drive train
simulation. This kind of pump tries to maintain preset pressure at
its outlet by adjusting its delivery flow in accordance with the
drive train system requirements. The flow rate equation for the
main pump is presented in (5).
Where, q is pump flow rate (m3/s), D is pump instantaneous
displacement (m3/rad), is pump angular velocity (rad/s), kleak is
pump leakage coefficient and P is the pressure differential across
the pump (Pa) [13], [14]. Torque at the pump driving shaft for the
main pump is presented in (6).
Where, mechis pump/motor mechanical efficiency. Pump
instantaneous displacement (D), is proportional to the Pressure
differential across the pump, Proportion of the pressure and
displacement is defined as (7) [13].
Where, Pmaxis maximum pressure (Pmax=Pset+Preg), Pset is pump
setting pressure, Preg is pump pressure regulation range, Dmax is
pump maximum displacement and k coefficient is defined as (8)
[13].
Leakage coefficient of pump/motor (kleak) and Hagen-Poiseuille
coefficient of pump/motor (kHP) are defined as (9).
Where, is fluid kinematic viscosity (cst), is fluid density
(kg/m3), nom is pump/motor nominal angular velocity (rad/s), V is
pump/motor volumetric efficiency, nom is nominal fluid kinematic
viscosity (cst) and Pnom is pump and motor nominal pressure (Pa)
[13]. The pump/motor leakage flow is determined based on the
assumption that it is linearly proportional to the pressure
differential across the pump/motor and can be computed by using the
Hagen-Poiseuille formula as (10).
Where, qleakis pump/motor leakage flow (m3/s), d and L are
geometric parameters of the leakage path, is fluid dynamic
viscosity (= ) [13].2. What ideas were used into the
study?SimHydraulic for Hydraulic Pump3. Is the study design
appropriate for answering the question?4.2. Hydraulic Motor[13]
www.Mathworks.com/Matlab/Simulink/SimHydraulic help. [14] J.
Johnson, Introduction to fluid power, 1nd ed.,Cengage Learning,
2002.1. What is the implementation procedure?The hydraulic motors
flow equation is presented as bellow.
Where, q is flow rate through the motors (m3/s), D is motor
displacement (m3/rad), is output shaft angular velocity (rad/s),
kleak is motor leakage coefficient and P is the pressure
differential across the motors (Pa) [13], [14]. The torque at the
motor output shaft (N.m) is defined as (12) [13], [14].
2. What ideas were used into the study?SimHydraulic for
|Hydraulic MotorIntroduction to fluid power3. Is the study design
appropriate for answering the question?4.3. Secondary control unit
1. What is the implementation procedure?In a hydrostatic
transmission, the displacement of its variable-displacement
hydro-motor is often regulated by the swash plate angle using a
hydraulic servo-mechanism. Therefore, the swash plate dynamics play
an important role in the dynamics of the hydrostatic transmission.
The secondary control unit simulation in presented in Fig. 9.
This unit is essentially a servo-cylinder controlled by a
proportional 4-way valve. The servo-cylinder drives the control
member of a variable-displacement motor represented in the model
with mass, spring, and damper. The model is designed as a
closed-loop control system with an angular velocity feedback.
Dynamic compensator PD is installed in the secondary control unit
to improve system stability. The hydrostatic drive train with
secondary control unit system has been developed by
Sim-Hydraulicsimulator environment (Fig.10). The variable
displacement pressure compensated pump, variable displacement
hydraulic motor and fixed displacement pump (booster pump)
parameters are presented in Table_1. The model is developed by two
main flexible pipelines with 30 (m) length and 0.05 (m2)
cross-sectional areas.
2. What ideas were used into the study?
3. Is the study design appropriate for answering the
question?Fig. 9. The Sim-Hydraulic model for hydro-motor control
unitFig. 10. The Sim-Hydraulic model for the proposed hydrostatic
drive train system in Matlab environmentTable 1.The main hydraulic
pump (MP), hydraulic motor (HM) and booster pump (BP) parametersd.
WIND TURBINE DEVELOPMENT 1. What is the implementation
procedure?The wind turbine development in Matlab-Simulink software
environment is shown in Figure 11. The model consists of three main
subsystems; a) wind model simulation, b) wind turbine rotor, c)
hydrostatic drive train with sensors and a simple gearbox.
2. What ideas were used into the study?3. Is the study design
appropriate for answering the question?Fig. 11. The wind turbine
development in Matlab- Simulink software environment
FSIMULATION & EXPERIMENTAL RESULTVII. SIMULATION RESULTS1.
Was the statistic used to test the hypothesis appropriate for the
scale of measurement and study design? Yes, it was.The output
results according to various input, are presented in two sections,
some different inputs are considered as bellow; a. The average wind
speed of 9 (m/s) & 16 (m/s) with unit step input of secondary
control unit.b. The average wind speed of 9 (m/s) with unit step
and unit ramp input of secondary control unit signals.2. Were the
study finding clearly presented? Yes, they were.3. Did the
statistical test support or fail to support the study
hypothesis?Yes, it support to the hypothesis aubout simulation 4.
Did the figure effective display the study results?6.1. Section
1The power coefficient, torque and power of wind turbine rotor,
torque and mechanical rotation of hydromotors (with unit step
signal of secondary control unit) in the average wind speed of
9(m/s) and 16(m/s) are presented in Fig. 12 to Fig. 16.
6.2. Section 2 The simulation results of the hydro-pump flow
rate, the servo-cylinder displacement in motor swash plate control
mechanism, hydraulic motor torque and mechanical rotation with unit
step and unit ramp signal of secondary control unit and the average
wind speed of 12 (m/s) are presented in Fig. 17 to Fig. 20
5. Can the results be used to answer the research question?
GCONLUSIONVIII. Conlusion1. Did the author offer a strong
explanation of their findings?2. What do the study findings mean
for theory?3. How do the study findings build upon previous
research?IX. Discussions1. Did the authors present their view of
study limitation
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