Power System II
PowerSystem
Lecturespreparedby
Prof.S.Shahnawaz Ahmed
PowerSystemI
A. Network representation
: Single line and reactance diagram of
power system and per unit.
B. Line representation: equivalent circuit
of short, medium and long lines.
C. L

INVERTER
DC to AC Conversion
(INVERTER)
General concept
Single-phase inverter
Harmonics
Modulation
Three-phase inverter
Inverter:
An inverter is an electrical device that converts DC to
AC power by switching the DC input voltage (or
current) in a pre-dete

Full Wave Rectifier
FW RECT:
Comparison between diode Bridge and
Center-tapped x-former Rect:
Maximum voltage across a reverse biased diode is twice
the peak value of the load voltage for center tapped Xformer Rectifier.
The center-tapped transformer re

Lecture-3
Power
Computation
Power Computation:
For analyzing and designing power electronics
circuits power computation is essential.
Due to the presence of nonlinear loads in
Electronic circuits non-sinusoidal waves are
generated in the circuit.
Power

DC-DC Converter
Boost & Buck-Boost converter
BOOST
CONVERTER
Step-Up (Boost)
Converter:
*When the switch S is in the on
state, the current in the boost
inductor increases linearly and
the diode D is off at that time.
*When the switch S is turned off,
the

PWM Inverter
PWM provides a way to decrease the THD of load current.
A PWM inverter output, with some filtering, can generally meet THD
requirement more easily than square wave switching scheme.
The unfiltered pwm output will have a relatively high THD, b

DC-DC converter
BUCK
CONVERTER
DC-DC converters:
The purpose of the chopper is to provide
variable d.c. voltage from a fixed voltage d.c.
source.
The power source for the chopper could be a
battery or a rectified a.c.
Applications of choppers are in dr

Rectifier/AC to DC converter
Half Wave Rectifier
A rectifier converts AC to DC.
Rectification: The process of converting the
alternating voltages and currents to direct
currents
Output purely DC or waveforms(V or I) might
required to have specified DC

Power Electronics
The objective of power electronics circuit is to
match the voltage and current requirement of the
load to the source. Basically PE circuits converts
one type or level of voltage or current waveform
to another and are hence called convert

Three-Phase Inverters
Consider three single-phase inverters in
parallel, driven 120 apart.
Three-Phase Inverter (continued)
Three single-phase full bridge inverters
12 transistors, 12 diodes, 3 transformers
Could it be simpler?
Alternative (Preferred) Con

Schedule for EEE321
Class Test
Class Topics
Test
Date
1
2
Already held
Already held
28 January 2013 Monday
11 February 2013 Monday
3
Already held
11 March 2013 Monday
4
Load flow and
Gauss-Seidel
method
25 March 2013 Monday
5
To be announced
in due time
8

Chapter 1
INTRODUCTION TO
POWER ELECTRONICS
SYSTEMS
Definition and concepts
Application
Power semiconductor
switches
Gate/base drivers
Losses
Snubbers
1
Definition of Power Electronics
DEFINITION:
To convert, i.e to process and control the flow of
e

Effective /RMS values
Effective/RMS value:
The effective value of a periodic voltage waveform
is based on the average power delivered to a
resistor. For a dc voltage across a resistor,
For a periodic voltage across a resistor, effective
voltage is defin

PowerSystemI
A. Network representation
: Single line and reactance diagram of
power system and per unit.
B. Line representation: equivalent circuit
of short, medium and long lines.
C. Load flow or Power Flow:
1. Formulation
2. Gauss Seidel method
3 Basic

EEE 321 Power System I
Student ID :
Test-1, Time: 20 Minutes;
Name:
Full marks : 10
28 January 2013
Signature:
1.A power system is represented by the following single line diagram. The components are rated as
follows.
a) Draw the reactance diagram with le

EEE 321 Power System I
Student ID :
Test-4, Time: 20 Minutes;
Name:
Full marks : 10
25 March 2013
Signature:
1. A 4 bus system and its bus admittance matrix are given below. Assume flat start for unknown voltage
magnitudes and phase angles. Compute the vo

EEE 321 Power System I
Student ID :
Test-2, Time: 20 Minutes;
Name:
Full marks : 10
11 February 2013
Signature:
1. The three-phase ratings of a three-winding transformer are:
Primary Y-connected, 66 kV, 20 MVA
Secondary Y-connected, 13.2 kV, 15 MVA
Tertia

Power System Load Flow
PowerSystemLoadFlow
Lecturespreparedby
Prof.S.Shahnawaz Ahmed
Load flow or Power Flow:
1. Formulation
2. Gauss Seidel method
3. Basic Newton Raphson, decoupled, fast
decoupled and DC load flow methods.
4 Power
4.
P
fl
flow
control:

Power System Load Flow
PowerSystemLoadFlow
Lecturespreparedby
Prof.S.Shahnawaz Ahmed
Load flow or Power Flow:
1. Formulation
2. Gauss Seidel method
3. Basic Newton Raphson, decoupled, fast
decoupled and DC load flow methods.
4 Power
4.
P
fl
flow
control:

SCR
Silicon Controlled Rectifier
Silicon Controlled Rectifier
A Silicon Controlled Rectifier (or Semiconductor Controlled
Rectifier) is a four layer solid state device that controls current
flow
The name silicon controlled rectifier is a trade name for

Power System Fault Analysis
PowerSystemFaultAnalysis
Lecturespreparedby
Prof.S.Shahnawaz Ahmed
Faultanalysis:
Fault
analysis:
1.Shortcircuitcurrentandreactanceofa
synchronousmachine.
2.Symmetricalfaultcalculationmethods
3.Symmetricalcomponents,sequence
ne

Power System Load Flow
PowerSystemLoadFlow
Lecturespreparedby
Prof.S.Shahnawaz Ahmed
Load flow or Power Flow:
1. Formulation
2. Gauss Seidel method
3. Basic Newton Raphson, decoupled, fast
decoupled and DC load flow methods.
4 Power
4.
P
fl
flow
control:

Three-Phase Diode Rectifiers
Three Phase rectifiers:
Two types:
(1)star rectifiers and
(2)bridge rectifiers
1)star rectifiers
This circuit can be considered as three single-phase half-wave rectifiers combined
together and sometimes referred to as a three

Cuk Converter
The inductor on the input acts as filter for the
dc supply to prevent large harmonic content.
Unlike the other converters (where energy
transfer is associated with the inductor)
energy transfer for cuk converter depends on
the capacitor C1