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Fundamentals of

Power Electronics and Power System

with MATLAB

Present by

K.PremKumar, M.E.,

Lecture EEE, SVCET,Tirunelveli.

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What is Power electronics

Electronics

Power

Control

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Power electronics devices

Thyratrons,ignitrons and mercury arc rectifier

SCR(Silicon Control Rectifier)

Power MOSFET IGBT

Power Transistor

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Application of power electronics

Battery charging

Electric traction

Solid state controllers for home appliances UPS

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Advantages

Higher efficiency

Long life

Small size and low weight Fast response

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Disadvantage

Produce harmonics in the supply system &

controlled system

Interference with communication system Produce low power factor at low voltage

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Types of power electronics converters

Diode rectifier

AC-DC converters

AC-AC converters DC-DC converters

DC-AC converters

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Power Electronics systems

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Power System

Generation

Transmission

Distribution

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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 ,230v for 1)

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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

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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

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Continuation

Secondary distributors

-voltage is step down to 400v or 230 v

- Link b/w DS to consumers

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Building and Simulating a Simple Circuit

Introduction

Building the Electrical Circuit with powerlib

Library

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Introduction

Explore the powerlib library

Learn how to build a simple circuit from the

powerlib library Interconnect Simulink® blocks with your

circuit

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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.

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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.

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Continuation

2. From the File menu of the powerlib window, open anew window to contain your first circuit and save it ascircuit1.

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, andFrequency parameters according to the values shown inCircuit to Be Modeled.

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

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

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Continuation

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

7. Copy the Parallel RLC Branch block, which can be foundin 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 RLCBranch 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 nowshows a single resistor.

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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.

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Continuation

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

13. The model of a line with uniformly distributed R, L, and C parametersnormally consists of a delay equal to the wave propagation time along

the line. This model cannot be simulated as a linear system because adelay corresponds to an infinite number of states. However, a goodapproximation of the line with a finite number of states can be obtainedby cascading several PI circuits, each representing a small section of theline.

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 themodel. Copy the PI Section Line block from the Elements library into thecircuit1 window, set its parameters as shown in Circuit to Be Modeled,and specify one line section.

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Continuation

15. The shunt reactor is modeled by a resistor in series with an inductor. You could use a Series RLCBranch block to model the shunt reactor, but then you would have to manually calculate and setthe 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 tospecify 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. Namethis block 110 Mvar. Set its parameters as follows:

Vn=424.4e3 V

Fn=60 Hz

P=110e6

QL=110e6 vars

QC=0

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Continuation

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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 blocknamed U1, a display system is needed. This can be any device found in

the Simulink Sinks library.

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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 boxand 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.

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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 theDC 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

5 0 . 0

2 5 . 0 u

100 V

0.4 mH Diode

IGBT

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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.

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Continuation

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

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

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

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

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

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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.

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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

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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 1Diode

IGBT

g

m

C

E

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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

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Continuation

15. Resize the various components and interconnect blocks by dragging lines

from outputs to inputs of appropriate blocks.

powergui

Continuous

Voltage Measurement

v+-

Vd c

Sc ope

R1

C1Pulse

Generator

L 1Diode

IGBT

g

m

C

E

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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 thescopes.

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THANK YOU

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