Power Electronics and Power System

gilamonsterbirdsElectronics - Devices

Nov 24, 2013 (3 years and 11 months ago)

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Fundamentals of

Power Electronics and Power Syste
m

with MATLAB

Present by

K.PremKumar
, M.E.,

Lecture EEE, SVCET,

Tirunelveli.

What is Power electronics


Electronics


Power


Control




Power electronics devices


Thyratrons,ignitrons and mercury arc rectifier


SCR(Silicon Control Rectifier)


Power MOSFET


IGBT


Power Transistor



Application of power electronics



Battery charging


Electric traction


Solid state controllers for home appliances


UPS


Advantages


Higher efficiency


Long life


Small size and low weight


Fast response

Disadvantage


Produce harmonics in the supply system &
controlled system


Interference with communication system


Produce low power factor at low voltage

Types of power electronics converters


Diode rectifier


AC
-
DC converters


AC
-
AC converters


DC
-
DC converters


DC
-
AC converters


Power Electronics systems

Power System


Generation


Transmission


Distribution


Structure of Power system


Generators
-

convert one form of energy to electrical energy


Transformer
-

transfer power or energy


Transmission lines


transfer power from one location to
another


Control equipments


protection purpose (breaker, relay.,)


Primary transmission (110kv,132kv,220kv,400kv or 700kv)


Secondary transmission(33kv or 66kv)


Primary distribution (11kv or 6.6kv)


Secondary distribution(400v for 3
Φ

,230v for 1
Φ
)

Transmission and distribution


Transmission system

-
Inter connection of two or more generating system

-
Divided in to primary and secondary transmission


Primary transmission

-
power loss very high

-
step up the voltage by step up transformer

-
transmit the power from SES to RES

-
primary transmission voltages are 110kv,132kv or 220k or

400kv or 765kv


Continuation…


Secondary Transmission

-

Link b/w RES to SS

-
voltage is step down by step down transformer

-
voltage values are 66kv or 33kv


Primary distributor

-

Link b/w SS to DS

-
voltage is step down to 11kv or 6.6kv

Continuation…


Secondary distributors

-
voltage is step down to 400v or 230 v

-

Link b/w DS to consumers

Building and Simulating a Simple Circuit



Introduction


Building the Electrical Circuit with powerlib
Library


Introduction



Explore the powerlib library


Learn how to build a simple circuit from the
powerlib library


Interconnect Simulink® blocks with your
circuit


Example 1:



The circuit below represents an equivalent power system feeding a 300 km transmission line.
The line is compensated by a shunt inductor at its receiving end. A circuit breaker allows
energizing and de
-
energizing of the line. To simplify matters, only one of the three phases is
represented. The parameters shown in the figure are typical of a 735 kV power system.


Procedure for simulation

1.
Open the
SimPowerSystems

main library by entering the following command at the
MATLAB® prompt.

>>powerlib

This command displays a Simulink window showing icons of different block libraries.


Continuation…


2.
From the File menu of the powerlib window, open a
new window to contain your first circuit and save it as
circuit1.

3.
Open the Electrical Sources library and copy the AC
Voltage Source block into the circuit1 window.

4.
Open the AC Voltage Source dialog box by double
-
clicking the icon and enter the Amplitude, Phase, and
Frequency parameters according to the values shown in
Circuit to Be Modeled.

5.
Note that the amplitude to be specified for a sinusoidal
source is its peak value

(424.4e3*
sqrt
(2) volts in this case).


Continuation…

6.
Change the name of this block from AC Voltage Source
to Vs.

7.
Copy the Parallel RLC Branch block, which can be found
in the Elements library of powerlib, set its parameters
as shown in Circuit to Be Modeled, and name it
Z_eq
.

8.
The resistance
Rs_eq

of the circuit can be obtained from
the Parallel RLC Branch block. Duplicate the Parallel RLC
Branch block, which is already in your circuit1 window.
Select R for the Branch Type parameter and set the R
parameter according to Circuit to Be Modeled.

9.
Once the dialog box is closed, notice that the L and C
components have disappeared so that the icon now
shows a single resistor.


Continuation…

10.
Name this block
Rs_eq
.

11.
Resize the various components and interconnect blocks by
dragging lines from outputs to inputs of appropriate blocks.


Continuation…

12.
To complete the circuit of Circuit to Be Modeled, you need to add a
transmission line and a shunt reactor.


13.
The model of a line with uniformly distributed R, L, and C parameters
normally consists of a delay equal to the wave propagation time along
the line. This model cannot be simulated as a linear system because a
delay corresponds to an infinite number of states. However, a good
approximation of the line with a finite number of states can be obtained
by cascading several PI circuits, each representing a small section of the
line.



14.
A PI section consists of a series R
-
L branch and two shunt C branches.
The model accuracy depends on the number of PI sections used for the
model. Copy the PI Section Line block from the Elements library into the
circuit1 window, set its parameters as shown in Circuit to Be Modeled,
and specify one line section.


Continuation…

15.
The shunt reactor is modeled by a resistor in series with an inductor. You could use a Series RLC
Branch block to model the shunt reactor, but then you would have to manually calculate and set
the R and L values from the quality factor and reactive power specified in Circuit to Be Modeled.



16.
Therefore, you might find it more convenient to use a Series RLC Load block that allows you to
specify directly the active and reactive powers absorbed by the shunt reactor.



17.
Copy the Series RLC Load block, which can be found in the Elements library of powerlib. Name
this block 110
Mvar
. Set its parameters as follows:



Vn
=424.4e3 V



Fn=60 Hz



P=110e6



QL=110e6
vars



QC=0


Continuation…

Continuation…

18.
You need a Voltage Measurement block to measure the voltage at node
B1. This block is found in the Measurements library of powerlib. Copy it
and name it U1. Connect its positive input to the node B1 and its
negative input to a new Ground block.

19.
To observe the voltage measured by the Voltage Measurement block
named U1, a display system is needed. This can be any device found in
the Simulink Sinks library.


Continuation…

20.
From the Simulation menu, select Start.

21.
Open the Scope blocks and observe the voltages at nodes B1
and B2.

22.
While the simulation is running, open the Vs block dialog box
and modify the amplitude. Observe the effect on the two
scopes. You can also modify the frequency and the phase.
You can zoom in on the waveforms in the scope windows by
drawing a box around the region of interest with the left
mouse button.


Example 2:



Find out the response of boost DC
-
DC converter. The IGBT is switched on
and off at a frequency of 10 kHz to transfer energy from the DC source to
the load (RC). The average output voltage (VR) is a function of the duty
cycle (a) of the IGBT switch:


100.0
L1 400.0u
T1 !NPN
D1 1N1183
50.0
25.0u
100 V
0.4 mH
Diode
IGBT
Procedure for simulation

1.
Open the
SimPowerSystems

main library by entering the following
command at the MATLAB® prompt.

>>powerlib

This command displays a Simulink window showing icons of different block
libraries.


Continuation…

2.
From the File menu of the powerlib window, open a new
window to contain your first circuit and save it as circuit2.

3.
Open the Electrical Sources library and copy the DC
Voltage Source block into the circuit2 window.

4.
Open the DC Voltage Source dialog box by double
-
clicking
the icon and enter the Amplitude according to the values
shown in Circuit to Be Modeled.

5.
Change the name of this block from DC Voltage Source to
Vdc
.

6.
Copy the Parallel RLC Branch block, which can be found in
the Elements library of powerlib, set its parameters as
shown in Circuit to Be Modeled, and name it L1.


Continuation…

8.
The inductance of the circuit can be obtained from the
Parallel RLC Branch block. Duplicate the Parallel RLC Branch
block, which is already in your circuit1 window. Select L for
the Branch Type parameter and set the L parameter
according to Circuit to Be Modeled.

9.
Once the dialog box is closed, notice that the R and C
components have disappeared so that the icon now shows a
single inductor.

10.
Name this block L1.


Continuation…

11.
Copy the IGBT block, which can be found in the element
library of powerlib, and connect as per circuit to be modeled,
and name IGBT.


Vdc
L
1
IGBT
g
m
C
E
Continuation…

12.
Copy the diode and parallel RLC branch block, which can be found in the
element library of powerlib, and connect as per circuit to be modeled,
and name diode, R and C.


Vdc
R
1
C
1
L
1
Diode
IGBT
g
m
C
E
Continuation…

13.
Copy the pulse generator, voltage measurement and scope block, which
can be found in the element library of powerlib, and connect as per
circuit to be modeled.

14.
Set the parameter of pulse generator as shown in figure


Continuation…

15.
Resize the various components and interconnect blocks by dragging lines
from outputs to inputs of appropriate blocks.


powergui
Continuous
Voltage Measurement
v
+
-
Vdc
Scope
R
1
C
1
Pulse
Generator
L
1
Diode
IGBT
g
m
C
E
Continuation…

16.
From the Simulation menu, select Start.

17.
Open the Scope blocks and observe the waveforms.

18.
While the simulation is running, open the
Vdc

block dialog
box and modify the amplitude. Observe the effect on the
scopes.


Thank you