Demonstration of wind power generation
Summary
TLDRThis video covers a detailed demonstration of wind power generation, focusing on the doubly fed induction generator (DFIG) setup used in modern wind turbines. It explains how wind energy is converted into electrical power through turbines, generators, and power converters. Key topics include the operating modes of DFIG (sub-synchronous, synchronous, and super-synchronous), the control strategies using rotor side converters (RSC) and grid side converters (GSC), and how power flows from the rotor and stator to the grid. The hardware setup and software integration are also highlighted, showing how wind emulation is achieved in a lab environment.
Takeaways
- 🌬️ Wind power generation involves capturing kinetic energy through wind turbines, which is converted to electrical energy via a gearbox, generator, and transformer.
- 🔋 The doubly fed induction generator (DFIG) is a partial variable wind system, known for its cost-effectiveness due to scaled-down converter sizes.
- ⚡ DFIG wind systems can inject power into the grid across a wide range of wind speeds, maintaining grid stability.
- 🔄 DFIG operates in three modes: sub-synchronous, synchronous, and super-synchronous, depending on the rotor speed relative to the grid frequency.
- 🌀 The rotor speed varies with wind speed, from sub-synchronous speeds in low wind to super-synchronous speeds in high wind.
- 📉 During sub-synchronous mode, the rotor draws power from the grid, while during super-synchronous mode, excess power is fed back to the grid.
- 🛠️ The DFIG hardware setup includes a wind emulator, slip ring induction motor, and back-to-back voltage source converters.
- 🔧 A DC motor emulates wind conditions and is controlled via a chopper, while buck converters manage the power flow.
- 🎛️ FPGA controllers, specifically the vivect FPGA, regulate the system, monitoring voltages, currents, and PWM signals for accurate control.
- 💡 Maximum power point tracking (MPPT) is implemented to optimize energy extraction from the wind turbine under varying wind conditions.
Q & A
What is the basic concept of wind power generation?
-Wind power generation converts kinetic energy from wind into electrical energy using wind turbines, a gearbox, a generator, power converters, and transformers to feed the energy into the power grid.
How does the Doubly Fed Induction Generator (DFIG) differ from conventional induction machines in wind systems?
-The DFIG allows power injection into the grid over a wide range of wind speeds, operating at both sub-synchronous and super-synchronous speeds. Unlike conventional machines, the DFIG's rotor can either absorb or deliver power, making it suitable for variable wind conditions.
What are the three modes of operation for a DFIG wind turbine?
-The three modes of operation are: sub-synchronous mode (rotor speed less than synchronous speed), synchronous mode (rotor speed equal to synchronous speed), and super-synchronous mode (rotor speed greater than synchronous speed).
What role does the rotor-side converter (RSC) play in DFIG systems?
-The RSC regulates the DFIG to operate in speed and power control modes, managing rotor current through field-oriented control (FOC) and facilitating maximum power point tracking (MPPT) under varying wind conditions.
How does power flow during sub-synchronous operation of the DFIG?
-In sub-synchronous operation, the rotor speed is less than synchronous speed, and power is drawn from the grid via the rotor-side converter to the rotor, enabling power injection into the grid through the stator.
What is the function of the grid-side converter (GSC) in a DFIG wind system?
-The GSC maintains the DC link voltage by controlling the flow of current between the DC link and the grid. It ensures smooth power transmission and reactive power management in coordination with the RSC.
What happens during synchronous mode of operation in a DFIG system?
-During synchronous mode, the rotor speed matches the synchronous speed, meaning no power is injected into or drawn from the rotor. All power is transferred to the grid through the stator.
What is the significance of Maximum Power Point Tracking (MPPT) in wind power generation?
-MPPT optimizes the rotor speed at different wind velocities to ensure maximum energy capture from the wind turbine. In DFIG systems, the RSC regulates rotor current to achieve MPPT.
How is the synchronization between the stator and grid achieved in a DFIG setup?
-Synchronization is achieved by adjusting the stator voltage and phase angle to match the grid's voltage and phase using rotor-side converter control. Once aligned, the stator can connect to the grid.
What hardware components are used in the DFIG wind turbine test bed demonstration?
-The DFIG test bed consists of a wind emulator, a slip ring induction machine, a DC motor, and back-to-back voltage source converters (RSC and GSC), controlled using an FPGA-based controller.
Outlines
🌬️ Introduction to Wind Power Generation
This paragraph introduces wind power generation as part of a course on smart grid technologies. It briefly describes how kinetic energy from wind is converted into electrical energy through a series of components: wind turbines, gearboxes, generators, power converters, and transformers. The paragraph highlights the aerodynamic modeling of wind turbines and recent advancements in wind generator technology, emphasizing the transition from fixed-type to partially and fully variable generators. It also explains the significance of the doubly fed induction generator (DFIG) system, particularly its cost-effectiveness and adaptability to different wind speeds.
⚡ Power Flow in a DFIG Wind System
This section delves into the mechanics of the DFIG wind system and its ability to manage power flow in two directions. It explains how the DFIG’s stator is connected to the grid at a fixed voltage and frequency, while the rotor operates at varying speeds, depending on the wind. The DFIG system can inject power into the grid across a range of wind speeds, making it versatile. The rotor draws power from the grid during sub-synchronous operation and contributes excess power during super-synchronous operation. The section concludes by outlining the three modes of operation: sub-synchronous, synchronous, and super-synchronous.
🔧 Hardware Setup and Components
This paragraph describes the hardware components involved in the wind turbine and DFIG setup. The system includes a wind emulator, a DFIG, and back-to-back voltage source converters. A slip ring induction machine is used in conjunction with a DC motor, which simulates wind characteristics. A buck converter helps mimic wind turbine behavior, and the control strategy for the converter is explained. The DC motor's output is regulated to simulate various wind speeds and emulate real-time wind conditions for the laboratory demonstration of the system.
🖥️ FPGA Controller and Synchronization Process
This section focuses on the control of the DFIG through a field-programmable gate array (FPGA) controller, which regulates various voltages, currents, and pulses. It details how synchronization between the grid and the DFIG’s stator is achieved using rotor-side control. The RSC (Rotor Side Converter) operates in speed power control mode, and the rotor current is regulated through a field-oriented control (FOC) method. The paragraph also explains the DC link voltage management, the role of the grid-side converter (GSC), and the maximum power point tracking (MPPT) for efficient energy conversion.
🔄 Synchronization and Speed Control Modes
This paragraph explains the process of entering speed control mode after synchronization is complete. The DFIG operates in three modes: sub-synchronous, synchronous, and super-synchronous. In the sub-synchronous mode, the rotor receives power from the grid. During synchronous mode, the rotor speed matches the grid frequency, and no additional power is drawn. In the super-synchronous mode, both the rotor and stator deliver power to the grid. The paragraph concludes by demonstrating how speed variations are controlled to simulate different wind conditions and operating modes.
Mindmap
Keywords
💡Wind Power Generation
💡Doubly Fed Induction Generator (DFIG)
💡Power Coefficient (Cp)
💡Rotor Side Converter (RSC)
💡Grid Side Converter (GSC)
💡Synchronous Speed
💡Sub-Synchronous Mode
💡Super-Synchronous Mode
💡Maximum Power Point Tracking (MPPT)
💡Synchronization
Highlights
Introduction to wind power generation using wind turbines, converting kinetic energy to electrical energy.
Overview of the aerodynamic modeling equations for assessing wind turbine performance based on varying wind speed.
Power generated by a wind turbine is a function of the power coefficient and wind speed.
Transition from fixed-type wind generators to partially variable and completely variable types for improved efficiency.
The doubly fed induction generator (DFIG) system allows bidirectional power flow between the grid and rotor.
DFIG operates effectively with varied wind speeds by allowing both sub-synchronous and super-synchronous operation modes.
During sub-synchronous operation, the rotor speed is less than synchronous speed, and power is drawn from the grid.
In super-synchronous mode, excess rotor power is fed back to the grid, allowing energy injection at higher wind speeds.
The DFIG system can function in three modes: sub-synchronous, synchronous, and super-synchronous, by controlling the rotor-side and grid-side converters.
Detailed explanation of hardware setup for wind turbine grid-connected operation, including wind emulator and voltage converters.
DFIG hardware setup consists of a slip ring induction machine, DC motor as a prime mover, and back-to-back voltage source converters.
A DC motor emulates wind characteristics through a buck converter, with control via armature voltage.
The FPGA-based controller manages DFIG’s stator and rotor current to achieve synchronization with the grid.
Maximum Power Point Tracking (MPPT) implemented using perturb and observe method to optimize wind energy capture.
In synchronous mode, the DFIG rotor operates at synchronous speed, with no power exchange through the rotor.
Transcripts
foreign
[Music]
dear student friends today we are going
to discuss on
demonstration of wind power generation
of the course titled smart grid Basics
to Advanced Technologies
now we are going to discuss on a test
bed for the demonstration of
wind power generation
and as you could see this is the brief
introduction to wind power generation
ideally we capture the kinetic energy
through wind turbines and through
gearbox to the generator and through
power converter to the Transformer and
hence the energy is being fed to the
power grid a typical wind power
generation
convert
kinetic energy of the Wind
to the useful electrical energy
the aerodynamic modeling equations
of the wind turbine
helps to access
the performance of the wind turbine
with respect to the varying wind speed
the power generated from the wind
turbine
is a function
of the power coefficient
and the wind speed
with the recent development in the
semiconductor technology
in the field of wind energy
the less productive fixed type wind
generators
are being replaced
by The partially variable and completely
variable types
among the variable type of generators
the dfig wind system which is one of the
partial variable type
is known for its cost effectiveness
due to the scaled down in the converter
size
the power converters
are rated to handle
complete range of wind speed variations
now focusing on doubly fed induction
generator
so called as dfig wpg the schematic
representation of the dfig wind system
along with the power flow is shown in
this light
is the name suggest
the doubly fed induction generator
is capable of feeding or observing
power in two directions
the stator part is directly exposed to
the grid
which works at fixed voltage
and frequency
henceforth
it is mandatory
that the stator of the dfig
is compelled to operate
as per the grid norms
however
this is only possible
if the rotor operates
at synchronous speed
in a practical scenario
the speed of the generator
keeps on wearing from the sub
synchronous speed
say in the morning hours
when the wind speed is low
to the super synchronous speed in night
hours
when wind speed is extensively High
thus
with the conventional induction machine
it is not possible
to inject power
from the wind system to the grid
with the dfig setup
it is possible to inject power
at varied wind speed
into the grid
via stator
over a speed range of plus or minus 30
percent
during the sub synchronous mode of
operation
since the wind speed is less
the positive slip power is drawn from
the grid
via
rotor side converter
grid side converter
combination to the rotor
such that
the prescribed power at the grid
frequency could be injected from the
stator end
by neglecting the losses of the back to
back converters
where PG equal to p r
we can say that
the power at PCC is equal to the
addition of the power generated by the
wind turbine that is the stator power at
the rotor power
here P equal to P S Plus p g that is the
summation of p s and p g
during the sub synchronous mode of
operation
rotor speed is less than synchronous
speed
and thus the slip is positive
similarly during the supersynchronous
operation
the Excess power from the rotor
in terms of negative slip
power flow out from the rotor via RSC
and GSC
combination thereby helping to follow
the grid Norms as per the nominal values
whereas during the synchronous mode of
operation
there is no power injected or observed
from the rotor and the entire power flow
from the wind system is transferred to
the green
via stator itself in summary
by controlling the RSC and GSC
the dfig wind system can be made to
function
in all the three modes of operation
now focusing on the hardware
demonstration
of the setup of wind turbine
grid connected operation of the dfig
setup
now before going into the demonstration
let us have a look at the overall
Hardware connections
dfig hardware setup
consists of three units mainly
the first one is a wind emulator
dfig
and back to back
voltage source converter
the laboratory setup of dfig is
basically a slip ring induction machine
coupled with DC motor
this DC motor
of rating 2.5 kilowatt
220 volt 10 ampere
which behaves similar to prime mover and
is controlled by Chopper control
providing different wind characteristics
for obtaining the wind emulator
the wind characteristics
along with the wind turbine x n is
mimicked with the help of a buck
converter
the DC motor output is controlled via
Armature voltage control for which the
semicron igbt stack is being used
an inductor and a capacitor is used to
form the buck converter
the control strategy for buck converter
is as shown in the schematic diagram
now the dfig control
so called wind emulator
it can be noticed that
the wind power
which is half of rho a c p v Cube
in the control scheme is calculated by
taking input wind velocity and pitch
angle
here the CP is the power coefficient
which is dependent on the pitch angle
and tip speed ratio
further the wind power is divided with
the measured speed of the rotor to
generate the reference talk
the motor reference current is obtained
by multiplying the torque reference with
the motor constant of value
K which is equal to
4.16 in our case
the current reference is then compared
with the actual current of the DC motor
the compared result is sent to the pi
controller thereby obtaining the
switching pulses
now the induction generator of 2.2
kilowatt
rated and is operated through the field
programmable
gate array fpga based controller
vivect fpga controller a firmware
version wcu10081e
is used which is capable of sensing
eight voltages and eight current signals
along with eight pwm pulses
while the stator of the slip ring
induction motor
is connected to the power amplifier via
a switch
the switch is initially open
and is further closed when the stator
voltage and phase angle is synchronized
with the voltage and phase of the grid
and phase angle using the rotor side
converter
after synchronization
RSC regulates
d f i g to operate
in the speed power control mode
rotor of slip ring induction motor is
connected to the RSC which is controlled
in the fpga platform
now if you look into the dfig control
through rotor site
field oriented control FOC
established on the vector control is
enlist for D and Q axis control
of rotor current
the maximum PowerPoint tracking mppt is
implemented using perturb and observe p
and O method by estimating
mppt reference rotor speed
at particular wind velocity regulating
the Q axis
of the rotor current IQ RSC
now the D X is part of the rotor current
is governed for managing the stator
power factor this is done by introducing
reactive power for smooth variation
further
the reference voltage is converted
to the ABC frame to generate the pwm
signals which is fed to the RSC switches
the RSC is connected to GSC via a DC
link and the job of the GSC is to
maintain the DC link voltage
now looking into grid side control the
generated DC link voltage when compared
with the measured voltage of DC link
generate error that is processed through
Pi controller to obtain d-axis reference
current
the measured GSC current d-axis
component tracks the reference value
with the pi controller to obtain the
reference DXs voltage
while the pi controller dealing with the
Q axis component of GSC current is
assigned to regulate reactive power
injection
now the software which is available
through WebEx suit for fpga controller
that run on HDL coder
in this platform we provide the
governing variables value
first we connect the WebEx via a lan
cable
to the PC
and connect the supply voltages
the supply voltage we give by power
amplifier
of rating 15 kilovolt ampere and 50
hertz
the three phase voltage is set in the
amplifier
140 volt to get line to line voltage of
240 volts
the grid voltage is reflected
in the software due to presence of
voltage sensor at that point
the main and the rotor branch circuit
breaker
is switched on and the DC link is
charged initially to 340 volts
then we enable
phase locked Loop and check the
reference Theta with the phase a voltage
once the DC link is charged
we enable the GSC control
to maintain the desired DC link voltage
which is said to say
30 volt greater than DC link voltage
that is close to
380 volts
we see that GSC track the DC reference
voltage and measured DC link voltage
is red as 385 volts
now the next step
is to enable
DC motor control to run the DC motor
to provide wind characteristic in the
rotation
here
we vary the duty of the chopper
gradually to make the motor run at more
than
900 RPM
we are wearing the duty and notice that
speed is keep on increasing
we can check the rotation here in the
speed panel
we see the DC motor is driving the
induction machine
next we provide
the p i value of the rotor side control
and enable the control Loop
the RSC first
is used to build up voltage in the
stator
site and then match the phase difference
of the grid
to the stator
till they align for the synchronization
purpose
now we will increase the reference value
to match the stator voltage magnitude
with the grid voltage using the D axis
control of the rotor
in this process
we also observe that the rotor current
is also increased
as it takes current from the grid
to build the stator voltage as from the
relation
the stator power is 1 by slip times the
rotor power I repeat in this process we
also observe that the rotor current is
also increased
as it takes current from the grid to
build the stator voltage is from the
relation the stator power is one by slip
times the rotor power
the slip is varied plus or minus 30
percent
so small current injected to rotor side
results in a larger voltage across the
stator
then we vary the Q axis of the RSC to
vary the Theta
we change the reference till Theta is
matched
if we see the grid and stator voltage
we see the waveform almost overlap with
one another
after voltage get matched in the
software then we check the
contactor of the grid side and Status
side and ensure that the voltage across
the contactor in multimeter is less than
20 volt
here we are getting a value of less than
10 volt across all three phases
by ensuring voltage is less then the
contactor connecting the stator
and the grid connection is closed and
then the synchronization is done by
enabling sync done in the software
simultaneously
now the control of RSC is changed from
synchronization operation to power speed
control mode
here we see that the three phase rotor
power is sent
now we enter the speed control mode and
Vary the wind speed to vary the rotor
speed
here we demonstrate the dfig in three
different operating modes
number one sub synchronous mode
to synchronous mode and three
supersynchronous mode now in case of the
sub synchronous mode the rotor angular
frequency is lower than the synchronous
angular frequency
where
Omega R is less than Omega s
we consider Omega s which is close to
1000 RPM and the slip is greater than
zero
the total power to the grid is 1 minus
slip times P stator
the stator delivers power to the grid
while the rotor receives power from the
grid
next we slowly increase the speed and
bring it in the synchronous mode
the rotor angular frequency
is equal to the synchronous angular
frequency where Omega r equal to Omega s
and the slip which is equal to zero
DC current flows into the rotor binding
the total power to grid is p which is
stator power only the stator delivers
power to the grid
if we further increase the speed of the
d f i g works in the super synchronous
mode
the rotor angular frequency is higher
than the synchronous angular frequency
that is Omega R is greater than Omega s
and hence the slips false Which is less
than zero
the total power
to the grid is p which is one plus slip
time P stator
now both the stator and the rotor
deliver power to the grid
with this we have today
understood how
a d f i IG wind turbine operates
and thank you for your attention
[Music]
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