International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014
Design, Modelling, Simulation and Analysis of V/F
Controller for WECS
Sunam,Dr.Shantharam
, Mr. Raghvendra ℎ
,
M.Tech Student.,Dept of ECE, Canara Engineering Collage, Manglore, Karnataka, India
2
H.O.D,ECE Department, Canara Engineering Collage, Manglore, Karnataka, India
3
Professor , ECE Department, Canara Engineering Collage, Manglore, Karnataka, India
1
Abstract-- Wind power generation has experienced a
tremendous growth in the past decade, and has been
recognized as an environmentally friendly and economically
competitive means of electric power generation. A wind
turbine can be designed for a constant speed or variable speed
operation. Variable speed wind turbines can produce 8% to
15% more energy output as compared to their constant speed
counterparts, however, they necessitate power electronic
converters to provide a fixed frequency and fixed voltage
power to their loads. Both voltage source voltage controlled
inverters and voltage source current controlled inverters have
been applied in wind turbines. This paper deals with the
design, modeling simulation and analysis of voltage –frequency
controllers for variable speed wind turbine using
MATLAB/SIMULINK
I.
WIND ENERGY CONVERSION SYSTEM(WECS)
The major components of a typical wind
energy conversion system include a wind turbine, generator,
interconnection apparatus and control systems. The wind
rotor, being the driving component in the conversion
system, converts the wind energy into mechanical energy. In
the case of variable speed wind turbines an electronic
inverter absorbs the mechanical power from the rotor,
converting it into electrical energy, which is then fed into a
supply grid.
Keywords: PMSG, wind turbine, IGBT diodes ,transformer
INTRODUCTION
There has been a huge increase in energy demand during
the last few decades. The asynchronous generators and
synchronous generators such as permanent magnet
synchronous generator (PMSG) are used for standalone
power generation. . Such distributed isolated systems
require energy storage systems usually batteries to stabilize
the voltage and frequency. Recently, voltage source
converter (VSC) based controllers are reported for voltage
and frequency control of PMSG generator based wind
energy conversion system. The voltage can differ from its
nominal conditions in a many various ways, including
changes in magnitude, frequency, RMS and continuity of
supply.
For 50 Hz systems the standard voltage recommended
by IEC Publication 38 is 230/400V.The main cause of
voltage variations in the grid are changes in the power
system load and in power production. The wind turbine
power may momentarily go from zero to maximum under
strong wind conditions, or from nominal power to zero in
the event of an emergency stop. Voltage and current
harmonics and inter harmonics are always present on the
utility grid. In case of a sudden wind blow or wind drop the
small spinning reserve will bring rise to frequency
fluctuations.
ISSN: 2231-5381
Fig.1. Block diagram of WECS
A Modelling equations of the WECS
The proposed WEC system consists of a wind turbine,
a permanent magnet synchronous generator, a VF controller and
a ripple filter and these components are modeled in the following
section. If ρ is the specific density of air (m3/s), A is the swept
area of the blades (m2) ,V is the wind speed (m/s), the power
coefficient is
,the aerodynamic power of the wind turbine
can be expressed as,
P = 0.5ρAC V
(1)
ω
λ is a function of tip speed ratio and is obtained as, =
where λ is the angular speed of the turbine with radius R. The ω
is obtained from the speed of the wind turbine.
=
=
−
−
,
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+
=0
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014
II.
VF CONTROLLER
2.
The proposed voltage and frequency controller consists
of an insulated gate bipolar junction transistor based voltage
source converter along-with battery energy storage system at
its dc link. The proposed controller is having bidirectional
active and reactive powers flow capability by which it controls
the system voltage and frequency with variation of consumer
loads and the speed of the wind turbine[1]-[3]. When there is
variation in wind speeds and corresponding variation in the
machine speed, the battery and consumer loads absorb such
amount of power by which desired frequency of the generated
voltage can be achieved. It is also having capability of
harmonic elimination and load balancing. The frequency
controller is done by extracting active component of the source
current.
A.
MODELING OF THE CONTROL SCHEME
Basic equations of the control scheme of the proposed
controller are as follows.
1.
Computation of Active Component of Reference
Source Current
Active component of reference source current is
estimated by dividing the difference of filtered instantaneous
load power ( )and output of the PI frequency controller to the
terminal voltage
(
= ( +
+ ) ).
Computation of Reactive Component of Reference
Source Current
The instantaneous quadrature components of reference
source currents are estimated as =
;
=
;
=
,
is obtained by output of the voltage PI
controller where input is voltage error between reference ac
terminal voltage (
)and ( )at the terminals of generator
where,
=
3.
√
+
√
,
=
√
+
(
)
√
,
√
=
+
(
)
√
.
Computation of Reference Source Current
Total reference source currents are sum of in-phase and
quadrature components of the reference source currents as
=
+ , =
+ , =
+ .
4.
PWM Signal Generation
Reference source currents( , , ) are compared with
sensed source currents ( , , ) The current errors are
computed as
=
− ,
=
− ,
=
−
. These the amplified signals are compared with fixed
frequency (10 kHz) triangular carrier wave of amplitude to
generate gating signals for IGBTs of VSC of the controller.
IV.
FUTURE WORKS
V/F controller can be implementing for wide range of
The load power (
) is =
+
, It is
wind
speed.
We can design different types of v/f controllers and
filtered to achieve its dc component (
),Where( , )
can analyses which can provide good controlling scheme, in turn
,( , )are obtained by three phase to two phase transform of
we can implement in the WECS.
ac load voltage
, ,
& ac load currents , , .Then
active component of reference source current is calculated as
V.
SIMULATION RESULT AND ANALYSIS
=2
The dynamic performance of the WECS with PMSG
and
VF controller under varying wind is shown in Fig. 3.
where ( )obtained by output of the of the frequency
proportional integral (PI) controller. Input to the controller is The wind speed can increase from 9 to 10m/s. During the
the frequency error between reference frequency and the system interval we are getting constant voltage and frequency. This
,
frequency. Instantaneous values of in-phase components of obtained by the PWM signal. The source voltages source currents (Is), load currents ( ), load voltage
reference source currents are estimated as
controller pulse, system frequency (f), wind power ( ) ,
=
;
=
;
= where PMSG speed
=
; =
; =
.
( rad /min) and load power (PL) are depicted in Fig. 3. It is
observed that the change in source power due to the change
in wind speed is absorbed by the controller to maintain the
system frequency to the reference value. The amplitude of
terminal voltage is maintained at the reference value under
various load disturbances.
Fig 2: v/f controller
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014
Fig 3 : Result.
V.
REFERENCES
[1]Bhim Singh, Senior Member, IEEE, and Gaurav Kumar Kasal-Voltage and
Frequency Controller for
Three-Phase Four-Wire Autonomous Wind
Energy Conversion System
[2] Dr. Bhim Singh Fellow IEEE, IET, INAE, IETE, IE (I), INSc Stand-Alone
Wind Energy Conversion Systems
[3] Bhim Singh, Shailendra Sharma -Neural Network Based Voltage and
Frequency Controller for Isolated Wind Power Generation
[4] M. E. Haque University of Tasmania-Control of a standalone variable
speed wind turbine with a permanent magnet synchronous generator
mehaque@utas.edu.au
APPENDICES
A. Wind Turbine Specifications
R=5.78m,C1=0.5176,C2 =116, C3 =0.4, C4 =5,
C5=21,C6=0.0068,C7=0.08,C8=0.035
B.
Permanent Magnet Synchronous Generator
415V, 50Hz, 16pole
R=0.03 Ω, X=2.1e-3H, J=0.7 kg-m2
C. Battery Model Specifications
Cb=25000F,
Rb=10kΩ
,
Rs=0.01Ω,
Voc=400V
D. Loads : 9KW,400V, 50Hz
E. Frequency PIcontroller: Kp=3,Ki=150
F. Terminal voltage PI controller: Kp =0.03, Ki =0.001
G. PWM switching frequency: 10 kHz
ISSN: 2231-5381
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