Transcript Direct Drive Permanent Magnet Generator for Wind Turbine

MODELING OF THE WIND TURBINE
WITH A PERMANENT MAGNET
SYNCHRONOUS GENERATOR
SINDHU.C.MANOHARAN
Edited By
Sarath S Nair
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CONTENTS
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Introduction
How does a wind turbine work
Model of wind turbine with PMSG
Different types of PMSG
Constructional features
Modeling of generator
Voltage and torque equation Permanent Magnet
Synchronous Generator
Control schemes of a permanent magnet (PM) generator
AC-DC-AC Power Conversion System
Conclusion
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INTRODUCTION
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Wind energy is one of the best technologies available today to
provide a sustainable supply to the world development.
In terms of the generators for wind-power application, there
are different types of wind turbine are there, fixed-speed wind
turbines and variable speed wind turbine
In fixed speed wind turbine, induction generators are used
(application in wind farms). But the limitations of such
generators are low efficiency and poor power quality
In variable speed wind turbine, doubly fed induction
generators and permanent magnetic synchronous generators
are used.
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HOW DOES A WIND TURBINE
WORK
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MODEL OF WIND TURBINE WITH PMSG
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VSC1=machine side power converter
T1=interface transformer
L1=inductance of the transformer
Ug=Output voltage of VSC1
fg=electric frequency
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DIFFERENT TYPES OF PMSG
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Radial flux permanent magnet machine (RFPM)
Axial flux permanent magnet machine (AFPM)
Transverse flux permanent magnet machine (TFPM)
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RFPM machines
The RFPM machine is producing the magnetic flux in the
radial direction with PMs which are radial oriented. It is the
best choice for direct drive wind turbine
AFPM machines
The AFPM machine is a machine producing magnetic flux in
the axial direction with permanent magnets. (application in
low speed low power range)
TFPM machines
The transverse flux (TF) principle means that the path of the
magnetic flux is perpendicular to the direction of the rotor
rotation.
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CONSTRUCTION OF PMSG
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Stator is composed by teeth formed by silicon iron sheets
These teeth are fixed by 2 bronze disks in their end.
Skewing is provided to avoid cogging torque
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PRINCIPAL PARTS OF GENERATOR
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PERMANENT MAGNET SYNCHRONOUS
GENERATOR
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Voltage for a PM generator in the d-q axis synchronous
rotational reference frame can be expressed as
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GENERATOR MODEL
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The dynamic model of PMSG is derived from two phase
synchronous reference frame ,in which q axis is 90 ahead of d
axis with respect to the direction of rotation
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GENERATOR MODEL (cont’d)
l
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The electrical model of PMSG in the synchronous reference
frame is
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Rs =stator resistance
Ld and Lq=inductance of the generator on d and q axis
Lld and Llq=leakage inductance of generator on d and q axis
We=electrical rotating speed(=Np Wg)
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GENERATOR MODEL (cont’d)
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Ld=Lds+ Lqs then equation becomes
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We assume Ld=Lq=L then equation becomes
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GENERATOR MODEL (cont’d)
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ed=0
eq=we
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Apply in above equation we will get equivalent circuit as
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TORQUE EQUATION
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As the inductance of d and q axis are equal the torque can be
expressed as follows…
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Which shows Torque can be regulated by current through q
axis
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CONTROL STRATEGY OF WIND TURBINE
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Pitch control strategy
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Yaw control
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DESIGN SPECIFICATION OF PMSG
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Rated power
= 2MW;
Rated wind speed
= 12m/s;
Resistance: Ra
=.1Ohm;
Inductance: L
=0.005H;
Gear ratio: ng
=77;
Number of pole pairs: np
=2;
Radius of wind turbine rotor: R=41m;
Equivalent inertia: J=8000kg.m2;
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AC-DC-AC POWER CONVERSION SYSTEM
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The amplitude and frequency of the output voltage
are not constant due to the variable speed and fixed
excitation of the permanent magnets.
3-phase diode rectifier is used for the AC/DC
conversion.
The SPWM (sinusoidal pulse width modulated)
inverter with filter is adapted for the DC/AC power
conversion.
The PIC microcontroller combined with dedicated
SA4828 chip is adopted to control of the SPWM
inverter for a 20kW direct driven PM generator wind
power generation system.
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SUMMARY
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The complete model of the variable speed wind
turbine with PMSG that is scheduled to connect AC
grid is discussed
The design characteristics Constructional features of
PMSG is discussed
The control strategy for AC/DC/AC power
conversion of the PM generator are also discussed
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REFERENCE
[1] E. Muljadi, S. Drouilhet, R. Holz and V. Gevorgian, "Analysis of
permanent magnet generator for wind power battery charging,“ IEEE-IAS
Annual Meeting, vol.1 , Oct. 1996 ,pp.541-548.
[2] A. J. G. Westlake, J. R. Bumby, and E. Spooner, "Damping the powerangle oscillations of a permanent-magnet synchronous generator with
particular reference to wind applications," IEE Proc.- Electr. Power Appl,
Vol. 143, No. 3, May 1996, pp. 269-280.
[3] Ozdemir Gol’ and Bijan Sobhi-Najafabadi, “Use of Impedance Models
in Permanent Magnet Synchronous Generator Design”
[4] Ming Yin, “Modeling of the Wind Turbine with a Permanent
Magnet Synchronous Generator for Integration”
[5] Rogel R. Wallace,Thomas A. Lipo, Luis A. Moran,Juan A. Tapia:Design
and Construction of a Permanent Magnet Axial Flux Synchronous
Generatorin Proc. IEEE PESC’90, San Antonio, TX, USA, vol. 1, pp.
325~332, Jun. 1990.
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