IRJET- Wind Turbine System Connected to a Permanent Magnet Synchronous Generator

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1756
Wind Turbine System Connected to a Permanent Magnet Synchronous
Generator
Priyanka Rajawat1, Dr. Vijay Bhuria2
1PG Scholar, Dept. of Electrical Engineering, M.I.T.S Gwalior, India
2Assistant Professor, Dept. of Electrical Engineering, M.I.T.S Gwalior, India
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Abstract - In today’s world electricity generation using
renewable sources are more popular. It includes sunlight,
wind, biomass, rain, tides, waves and geothermal heatetc.This
paper presents a mathematical modelling and simulation of a
small wind turbine for extracting wind power and convert the
kinetic energy of wind to electrical energy using permanent
magnet synchronous generator (PMSG) without using gear
box.
For implementing the model of wind turbine system, basic
mathematical equations are carried out and the tool used is
Simulink/MATLAB. The technique used is Zero d-axis control.
The simulation results here demonstrate the effectiveness of
proposed mathematical model of the small wind turbine to
determine its dynamic behaviors.
Key Words: Doubly fed induction generator (DFIG),
Maximum power point tracking (MPPT), Permanentmagnet
synchronous generator (PMSG), and Windturbinegenerator
(WTG).
1. INTRODUCTION
Power generation by renewable energy sources is becoming
more popular and economical than the traditional
generation system to supply reliable power in areas not
served by conventional power grids. The demand of global
energy in 2040 will expand to be about 30% higher than in
2010[1].
In the last fifteen years the penetration of the wind turbine
power generation is dramatically increased world-wide [2].
The wind turbine system is one of the most known and used
source of renewable energy. It has not only a several
environmental and economic advantages, but also, it can be
installed in all regions. Around 83% of wind capacities are
located in these five countries, German, United State of
America, Denmark, India and Spain [3-4]. The wind turbine
system produces the electrical energy from the wind speed
after converting it to mechanical energy by the generator.
For this purpose, we can find several types of generators
such as the permanent magnet synchronous generator
(PMSG) [5] [6], squirrel-cage induction generator (SCIG) [7]
[8], doubly fed induction generator (DFIG) [9][10][11][12],
and wound rotor induction generator (WRIG). PMSG has
received much attention in wind energy applicationbecause
of their property of self-excitation, which allows an
operation at a high power factor and high efficiency. There
are so many researcherswhose main focusisonthedynamic
modelling and simulation of the small wind turbine system
so as to get its dynamic physical model and the appropriate
outputs such as the current, the voltage, and the power.
Further, many control strategies can be applied to control
the permanent magnet synchronous generator in order to
achieve good results. In [13], a novel control strategy for the
extraction of maximum power and operationofdirectdriven
PMSG based stand-alone variable speedwindturbinesystem
is shown. In some papersthe wind turbine model dealswith
the mechanism of variable speed operation of the turbineby
a pitch control. As in [14], the modelled system consists of a
PMSG model, a pitch-angled controlled wind turbine model
and a drive train model. The control scheme include a pitch
angle control and a speed control of the generator. The pitch
angle control uses wind speed signals and power output of
the generator as the inputs and vector control is
implemented for the speed control of the generator in the
dq-synchronous rotating reference frame. The field
orientation is realized by setting id (ref) =0 and q-axis
component of the current iq controls the rotational speed.
In [15] a dynamic modelling and simulation of wind turbine
connected to PMSG generator is shown and two different
control techniquesare compare: the fractional-orderandthe
classical control.
This paper consists of four sections, in which section II
shows the aerodynamic and the electrical dynamics of a
PMSG generator with control technique i.e. Zero d-axis
current control (ZDC). Section III and IV shows the
simulation results of mathematical model and the overall
conclusion.
Installed capacity of wind turbine system from 2000-2017

2. AERODYNAMIC MODEL OF SMALL WIND TURBINE
SYSTEM
In this part we are going to study the mathematical model of
a wind turbine system connected to PMSG generator and an
AC load.
PMSG AC LOAD
WIND TURBINE
Fig.2.Wind turbine system connected to PMSG generator.
The whole wind turbine system consists of:
• Wind turbine.
• PMSG generator.
• AC load.
Generally in grid connected wind turbine system, power
electronic converters are required but here in this paper the
wind turbine system isdirectly connected to ACloadwithout
the power electronic converter. (Fig 2)
2.1 MODELLING OF THE WIND TURBINE
The mechanical power captured by the wind turbine is
given by Eq (1)
………………..... (1)
Where, p = 1.225 is the air density, R (m) is the blade
radius and Vw (m/s) is the wind speed.
Cq represents the torque coefficient. It can be computed
using Eq (2)
……… (2)
Where,
………………….……... (3)
The following coefficients were obtained:
C1=0.5176, C2=116, C3=0.400, C4=4, C5=21, C6=0.0068
Where is the pitch angle and is the tip speed ratio, and
given as Eq (4)
…………….………………………….. (4)
(rad/s) is the rotor speed.
The power coefficient Cp can be given by Eq (5)
……………………………………. (5)
The torque of the turbine Tw (N.m) can be obtainedbyEq(6)
………………………. (6)
2.2 MODELING OF THE PMSG GENERATOR
The electromagnetic torque produced by the PMSG
generator is given by Eq (7):
………..…. (7)
Where, P is the number of pole pairs, 𝐿𝑑 (H) and 𝐿𝑞 (H)
are the 𝑑𝑞-axisself-inductanceof the synchronousgenerator
and 𝜆𝑟 (Wb (rms)) is the rotor flux linkages.
𝑖𝑑𝑠 And 𝑖𝑞𝑠 present the 𝑑𝑞-axisstatorcurrentofthePMSG
generator:
………………….…. (8)
……....(9)
𝑅𝑠 is the stator winding resistance of the PMSG generator.
𝑣𝑑𝑠 and 𝑣𝑞𝑠 present the 𝑑𝑞-axis stator voltage:
……………….…... (10)
……. (11)
Where, 𝜔𝑟 (rad/s) is the rotor speed. It can be written by
using Eq (12).
…………………………. (12)
𝐽 is the moment of inertia.

2.3 CONTROLLING SCHEME (ZERO D-AXIS CURRENT
CONTROL)
here are several control schemes are used to control
PMSG generator. In this paper a zero d-axis current (ZDC)
control is applied, where the d-axis stator current of the
generator 𝑖𝑑𝑠 is set to zero.
The electromagnetic torque is given as (13):
…………….……….(13)
Where, the stator current 𝑖𝑠 calculated as:
…………….…………(14)
The 𝑑𝑞-axis stator reference current of the PMSG
generator is given as:
………………..……….…….(15)
0 ……………………………………….….. (16)
Where, Te* is the torque reference and given as:
…………………………………….…. (17)
The 𝑑𝑞-axis stator current and voltage of the PMSG
generator can be written, by the following equation.
…………………………….. (18)
…………...(19)
……………………………………….. (20)
………………………………………… (21)
Rs (ohm) is the stator winding resistance of the PMSG
generator.
The mechanical power of the PMSG generator is givenbythe
Eq (22).
………………………. (22)
Tm is the mechanical torque and 𝜔m is the rotor mechanical
speed. Here the mechanical speed is equal to the rotor
electrical speed 𝜔𝑟 because of no gearbox.
The active power delivered to the load:
………………………………….(23)
………………….…….. (24)
Where Pcu,s is the stator winding loss:
……………………………………… (25)
The reactive power delivered to the load is determined by
using Eq (26).
……………….. (26)
and are rms stator current and voltage:
………………………………… (27)
………………………………... (28)
PMSG
(3P/
2)*λr.is
K.Wr^2
PI
(P/J)(Tw-
Te)
2/(3.P.λr) PI
iqs
Iqs*
ids
Ids*
Te*Wr
Te
Tw
Is,vs
Fig 3.ZDC control scheme of PMSG generator.
In this paper ZDC control strategy is used, in which d-axis
stator current is made zero to get maximum torque with a
minimum stator current. The ZDC control scheme of the
PMSG generator is shown in fig.3.
3. SIMULATION RESULTS
The model Simulink of the wind turbine systemconnectedto
a PMSG generator during 10 s is shown in fig.4. It is carried
out using MATLAB/Simulink.

Fig.4. Model Simulink of wind turbine system.
Figure 5 presents the model Simulink showed below the
block “wind turbine” where its input parameters are the
wind speed, pitch angle, which is equal to zero, and the
generator speed which is equal to the rotor speed generated
by the PMSG generator.
Fig.5. Model Simulink under block “wind turbine”.
The model Simulink below the block “PMSG” generator is
plotted in Fig.6. Its Input parameter is the torque generated
by the wind turbine and the output parameter are the rotor
speed, electromagnetic torque, current, voltage, and
mechanical, active and reactive power.
Fig.6. Model Simulink under block “PMSG”
The parametersof the wind turbine system are summarized
in Table 1.
Table -1: Parameters of Wind Turbine System
Maximum wind speed 18.73 (m/s)
Pitch angle 0 deg
C 2.245 m
Stator winding resistance of
synchronous generator
2.87 ohm
dq-axis self-inductance of
synchronous generator.
0.05297 H
Number of pole pairs 2
Rotor flux linkages 6.7302 Wb rms)
Moment of inertia 0.1278
The most important parameter of wind turbine system is
wind speed. Its variation is shown in Fig.7.
Time (second)
Fig.7.variation of wind speed.
Fig.8 shows the variation of torque Tw (Nm) generated by
wind turbine system.
Time (second)
Fig .8. Variation of torque generated by wind turbine

Time (second)
Fig.9. Variation of mechanical power
Time (second)
Fig.10. Variation of active power
Time (second)
Fig.11. Variation of reactive power
Time (second)
Fig.12. Variation of current
Time (second)
Fig.13. Variation of voltage
The simulation result show that the mechanical and active
power vary according to the variation of wind speed. The
maximum wind speed is 18.7 m/s.
3. CONCLUSION
Simply, the enhancement of the renewable energy is the
intension of numerous studies concerning its advantages in
terms of efficiency, reliability and cost. The wind system is
considered one of several power supplies which is used to
supply energy with reduced pollution. This papersobjective
is to expand a dynamic model of a small wind turbinesystem
primarily based on PMSG generator. The simulation results
display the efficiency of shown mathematical model to
decide the expected dynamic behaviors along with: voltage,
current and electricity using MATLAB/simulation.
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