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EVALUATION OF FILTER DESIGN AND HARMONIC ANALYSIS USING
PSCAD/ EMTDC
AIMI SHAKIRA BINTI YUSEH
This thesis is submitted as partial fulfillment of the requirements for the award of the
Bachelor of Electrical Engineering (Power Systems)
Faculty of Electrical & Electronics Engineering
Universiti Malaysia Pahang
NOVEMBER 2010
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“All the trademark and copyrights use herein are property of their respective owner.
References of information from the sources are quoted accordingly otherwise the
information presented in this report is solely work of the author.”
Signature : __________________________
Name : AIMI SHAKIRA BINTI YUSEH
Date : 30 NOVEMBER 2010
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ACKNOWLEGDEMENT
Alhamdulillah, His Willingness made it possible for me to complete this final
year project. I would like to express my appreciation to my supervisor, Mr. Mohd
Redzuan bin Ahmad for his guidance, advices and motivation to accomplish this project.
Without his continued support and interest, this thesis cannot be achieved as presented
here. I also appreciated to all my colleagues and others who have provided assistance at
various occasions. Their views and help are very useful.
I also would like to thank to all UMP lecturers whom had helped directly or
indirectly in whatever manner to make this project become a reality.
My special thanks to my mother, Mrs. Saiah binti Ahmad and my siblings who
are always support and prey on me throughout this project. Their blessing gave me the
high-spirit and strength to face any problem occurred and to overcome the rightly.
Their great cooperation, kindheartedness and readiness to share worth
experiences will be always appreciated and treasured by me. Thank you.
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ABSTRACT
Nowadays, electricity becomes one of the most important necessities to the
world. Designing of filter is one of the methods to improve power quality in delivering
electrical power to the customer. This project presents the evaluation of filter design and
harmonic analysis to the system network. Here, it helps the utility system by increase the
capability to power supply with fewer losses. The IEEE test system are used in this
project as a base line diagram before any analysis which is load flow analysis, transient
stability analysis, harmonics analysis according to active filter that approach to the
system. The 4-bus test system and 9-bus test system analyzed by using MATLAB and
PSCAD. Generally, power transmission and distribution are design for operation with
sinusoidal voltage and current waveform at a constant frequency. However, when non-
linear load such as thyristor drives, converters and arc furnace are connected to the
system, excessive harmonic currents are generated and this causes both current and
voltage distortion. The active filter concept uses power electronics to produce harmonic
components which cancel the harmonic components from the nonlinear loads.
Evaluation of harmonics filter is crucial to make sure the filter is in optimum design, not
under or over design. The result shows the effectiveness of active filter design modeling
by PSCAD software and analysis the harmonic in simulation part. As a conclusion, the
active filter that design improved the quality of the power system network in distributed
electricity to the customer.
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ABSTRAK
Pada masa kini, bekalan elektrik merupakan salah satu keperluan yang amat
penting kepada dunia. Penggunaan penapis merupakan salah satu idea untuk membaik
pulih kualiti dalam proses menghantar bekalan kuasa kepada pengguna. Projek ini
membentangkan tentang penilaian penapis aktif dan analisis selaras kepada sistem. Ini
dapat membantu sistem untuk membekalkan kuasa tanpa kerugian dalam usaha untuk
meningkatkan keupayaan. Sistem ujian IEEE digunakan dalam projek ini sebagai litar
asas untuk analisis berkaitan arus beban, suntikan selaras kepada penapis aktif sebelum
dimasukkan ke dalam sistem. Sistem ujian 4-bas dan 9-bas digunakan untuk
menganalisis keupayaan dengan menggunakan perisian MATLAB dan PSCAD. Secara
umumnya, sistem kuasa direka untuk operasi voltan dan arus gelombang pada frekuensi
yang tetap. Apabila beban bukan linear seperti thyristor, pengubah dan pemancar
pembakar berhubung dengan sistem, lebihan arus selaras terhasil dan menyebabkan
kesemua arus dan voltan berubah. Penapis aktif menghasilkan komponen selaras dengan
membatalkannya daripada beban bukan linear. Keberkesanan rekabentuk penapis
menggunakan perisian PSCAD dan menganalisis keselarasan terhasil. Kesimpulannya,
penapis aktif direka bagi memperbaiki kualiti sesuatu sistem kuasa sebelum di
bahagikan kepada pengguna.
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TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF SYMBOLS xii
LIST OF ABREVIATION xiii
LIST OF APPENDICES xiv
1 INTRODUCTION
1.1 Project background 1
1.2 Problem statement 2
1.3 Objectives 2
1.4 Scope of project 3
1.5 Literature review 4
1.6 Thesis outline 5
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2 HARMONIC AND FILTER DESIGN
2.1 Introduction 6
2.2 IEEE standard test system 7
2.3 Overview on harmonics
2.3.1 Definition of harmonics 9
2.3.2 Linear and non-linear load 9
2.3.3 Harmonic current flow 12
2.4 Harmonic Filter
2.4.1 Introduction of filters 14
2.4.2 Passive filter 15
2.4.3 Active filter 16
2.5 Summary 17
3 MODELLING OF ACTIVE FILTER USING PSCAD/ EMTDC
3.1 Introduction 18
3.2 Flow chart of project 18
3.3 Tools of software
3.3.1 MATPOWER 22
3.3.2 PSCAD/ EMTDC 23
3.4 Active filter configuration 24
3.5 Model active filter 25
3.6 Summary 27
4 RESULTS AND DISCUSSIONS
4.1 Introduction 28
4.2 IEEE 4-bus test system
4.2.1 Load flow analysis 33
4.2.2 Harmonic analysis 38
4.2.3 Transient stability analysis 41
4.3 IEEE 9-bus test system
4.3.1 Load flow analysis 48
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4.3.2 Harmonics analysis 54
4.3.3 Transient stability analysis 58
4.4 Summary 59
5 CONCLUSIONS AND RECOMENDATION
5.1 Conclusion 60
5.2 Recommendation 61
REFERENCES 63
APPENDICES 66
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LIST OF TABLES
TABLE NO. TITLE PAGE
4.1 Line data of 4-bus test system 33
4.2 Voltage magnitude and voltage angle from MATLAB 35
4.3(a) The load flow in MATLAB 35
4.3(b) The load flow in PSCAD 36
4.4 Power losses in MATLAB & PSCAD 38
4.5 Line data of 9-bus test system 48
4.6 Voltage magnitude and voltage angle from MATLAB 50
4.7(a) The load flow in MATLAB 50
4.7(b) The load flow in PSCAD 51
4.8 Power losses in MATLAB & PSCAD 54
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LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 IEEE 4-bus test system 7
2.2 IEEE 9-bus test system 8
2.3 Voltage and current waveform for linear 9
2.4 Voltage and current waveform for non-linear 10
2.5 Waveform with symmetrical harmonic component 11
2.6 Distorted current included voltage distortion 12
2.7 Second order passive low pass filter 14
and Second order active low pass filter
3.1 Flow chart of project 21
3.2 On-line frequency scanner (FFT) 27
4.1 Single line diagram of 4-bus test system 34
4.2(a) Comparison graph of real power from bus injection 36
between MATLAB & PSCAD 4-bus test system
4.2(b) Comparison graph of reactive power from bus injection 37
between MATLAB & PSCAD 4-bus test system
4.3(a) Comparison graph of real power to bus injection 37
between MATLAB & PSCAD 4-bus test system
4.3(b) Comparison graph of reactive power to bus injection 38
between MATLAB & PSCAD 4-bus test system
4.4 IEEE 4-bus test system with nonlinear load 39
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4.5 Injection of harmonic current and active filter 40
on 4-bus test system
4.6 Control circuit for test system 41
4.7 Analysis of 4-bus test system 42
4.8 Single line diagram of 9-bus test system 49
4.9(a) Comparison graph of real power from bus injection 52
between MATLAB & PSCAD 9-bus test system
4.9(b) Comparison graph of reactive power from bus injection 52
between MATLAB & PSCAD 9-bus test system
4.10(a) Comparison graph of real power to bus injection 53
between MATLAB & PSCAD 9-bus test system
4.10(b) Comparison graph of reactive power to bus injection 53
between MATLAB & PSCAD 9-bus test system
4.11 IEEE 9-bus test system with nonlinear load 55
4.12 Injection of harmonic current and active filter 56
on 9-bus test system
4.13 Control circuit for test system 57
4.14 Analysis of 9-bus test system 58
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LIST OF SYMBOLS
P - Real power
Q - Reactive power
S - Apparent power
R - Resistance
L - Inductance
C - Capacitance
Cshunt - Shunt capacitance
Vb - Base voltage
Sb - Base apparent
Ract - Actual value of resistance
Lact - Actual value of inductance
XLact - Actual value of line inductance
XCact - Actual value of line capacitance
Lpu - Per-unit value of inductance
XLpu - Per-unit value of line inductance
XCpu - Per-unit value of line capacitance
π - Pi
ω - Angular frequency
f - Frequency
b - Susceptible line charging
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LIST OF ABBREVIATION
PV - Generator bus
PQ - Load bus
RMS - Root-mean-square
DC - Direct current
CHAPTER 1
INTRODUCTION
1.1 Project Background
Power transmission and distribution system are design for operation with
sinusoidal voltage and current waveform in constant frequency. However, when non-
linear load like thyristor drives, converters and arc furnace are connected to the
system, excessive harmonic currents are generated and this causes both current and
voltage distortion. Harmonic filter is the best way to eliminate the distortion from
power system network.
This project presents a design of an active filter following to harmonic
analysis. It focuses on the performance of active filter through the IEEE standard test
system by generating the harmonic analysis. It is one of the methods in reducing the
harmonic distortion following the system design. The calculation of design
parameters for filter component of harmonic active filter are applied in this project.
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1.2 Problem Statement
Harmonic distortion can cause severe disturbance to certain electrical
equipment. It is the duty of the electric utility to provide a clean supply. Many
countries now set limits to the harmonic distortion allowed on the distribution
networks. Evaluation of harmonics filter is crucial to make sure the filter is in
optimum design, not under or over design. This project is essential in terms of power
efficiency and power handling deliver system network. It is important because this
aspect related to the most transmission and distribution system requirement.
1.3 Objectives
The aim of this project is to evaluate the performance of active filters and
also to analyze the harmonic distortion cause by harmonic source. To achieve this
aim, the project is carried out for the following objectives:
i. to design an active filter in order to reduced harmonic distortion through to
the power system network.
ii. to ensure the performance of filter design that approach to the system is
efficient.
iii. to determine the distortion that existed through the system by analyze the
harmonic.
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1.4 Scope of Project
The main focus in this project is by the calculation of design parameters for
filter component of harmonic active filter. It affects overall result when any mistakes
error forms the calculation. By using PSCAD/ EMTDC, the IEEE standard test
system which is 4 bus and 9 bus constructed together with filter circuit before
continue the harmonic analysis as the result. An active filter is limited to the
performance in test system as power system network using proportional design.
1.5 Literature Review
In electrical power system, transmission and distribution networks are
designed to operate with sinusoidal voltage and current having constant frequency.
However there are number of non -linear loads, such as thyristor drives and
converters that generate harmonics on the network, causing distortion in the voltage
and current waveforms.
The harmonic voltage levels on electric power distribution systems are
generally increasing due to the changing nature of the system load. Hence, harmonics
levels will soon require reduction through the application of tuned filters. Harmonic
distortion in electric power systems affects the whole system environment, often at
large distances from the original sources. Like many other forms of pollution,
harmonics are a form of electrical pollution in the power system.
Harmonic distortion in power systems is increasing with the wide use of
nonlinear loads in solid state power devices. Thus it is important to analyze the
various harmonic problems, to evaluate the harmonic level and to eliminate
harmonics prior to their becoming a serious problem.
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Harmonic distortion in power distribution systems can be suppressed using
two approaches namely, passive and active powering. Remarkable progress in power
electronics had spurred interest in active power filter (APF) for harmonic distortion
mitigation. The basic principle of APF is to utilize power electronics technologies to
produce specific currents components that cancel the harmonic currents components
caused by the nonlinear load. [1]
The filter is design used when the main objective is not the reactive power
compensation at the fundamental frequency, but to reduce the harmonic distortion in
the supply system. The harmonic filtering is one of the solutions to prevent the
troublesome harmonics from entering the rest of the system. [2]
Harmonic filters provide low impedance paths to harmonic currents and thus
prevent them from flowing into the power network. Harmonic analysis program
computes indices such as total voltage harmonic distortion factor at system buses to
evaluate the effect of the harmonic sources and to evaluate the effectiveness of the
harmonic filters. [3]
1.6 Report Outline
This report covers all part of evaluation of filter design and harmonic analysis.
It is about the quality of power system network that used in daily life. The distortion
existed to the system on the harmonic analysis. So that, this project taken for
reducing the distortion by design and evaluate the filter as a method to overcome this
problem of the system.
Chapter 1 is a brief review of this project. It includes the basic needed for this
project. It also mention about the general concept for this project.
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Chapter 2 describe about the main topic of this project that is harmonic and
filter design. It includes overview of harmonic which is definition, linear and non-
linear load concept and harmonic current flow. Besides the harmonic elimination
explain about filters which is passive and active filter.
Chapter 3 describe about the modeling of active filter by using PSCAD
software. This chapter includes developing the tools that approach to this project
which is MATPOWER and PSCAD software. The methodology for this project also
explains here.
Chapter 4 describe about result and discussion for this project. The result
includes results that show such the configuration of the IEEE 4-bus test system and
IEEE 9-bus test system. It also covered the load flow analysis, transient stability
analysis and harmonic analysis.
Chapter 5 includes the conclusion for overall project and also future
recommendation.
CHAPTER 2
HARMONIC AND FILTER DESIGN
2.1 Introduction
This chapter explains about the overall overview of this project. The first is about
test system that being used in this project which is IEEE 4-bus test system and 9-bus test
system. It describes overall function of the test system. The data for the system attached
in appendix.
Next is about the overview of harmonics includes the definition, linear and non-
linear configuration and also harmonic current flow. It more shows on how harmonic
existed to the system. Then, this chapter also includes the harmonic filter by further
explanation on passive filter and active filter.
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2.2 IEEE Standard Test System
A single line diagram of the IEEE 4-bus standard test system is shown in Figure
2.1. It consists of three synchronous machines with IEEE type-1 exciters, three of which
are synchronous compensators used only for reactive power support. There are 4 loads
in the system totaling 500 MW and 309.9 Mvar. The dynamic data for the generators
exciters was selected. The model details are discussed in the following sections, and the
corresponding data is given in Appendices A.
Figure 2.1 IEEE 4-bus test system
A single line diagram of the IEEE 9-bus standard test system extracted from [6]
is shown in Figure 2.2. It consists of three synchronous machines with IEEE type-1
exciters, three synchronous generators total up by 820 MW and -900 to 900 Mvar, 3
loads in the system totaling 315 MW and 115 Mvar. The model details are discussed in
the following sections, and the corresponding data is given in Appendices B.
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Figure 2.2 IEEE 9-bus test system
2.3 Overview on Harmonics
In this part, the theoretical of harmonics attached. In practically, power system
network still have distortion that came from harmonic although theoretically say that
harmonic can be cancel up using some kind of method. This part shows the definition of
harmonics, types of load and also harmonic current to clearly understand the project.
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2.3.1 Definition of Harmonics
Harmonics are the odd integral multiples of fundamental frequency resulting in
the distortion of supply waveform due to interference by superposition. Harmonics are
defined as the sinusoidal components of a repetitive waveform which consist of
frequencies that are exact multiples or harmonic orders of fundamental frequency. [6] A
complete set of harmonics then makes up a Fourier series which together represent the
original waveform. Harmonics are currents, usually in multiples of the supply
fundamental frequency, produced by non-linear loads such as the AC to DC power
conversion circuits. For example a 50Hz supply, the 5th harmonic is 250 Hz, 7th
harmonic is 350 Hz and other order harmonics.
2.3.2 Linear and Non-linear Load
A linear element in a power system is a component in which the current is
proportional to the voltage. In general, this means that the current wave shape will be the
same as the voltage. Typical examples of linear loads include motors, heaters and
incandescent lamps.
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Figure 2.3 Voltage and current waveforms for linear
In the other side, the current wave shape on a non-linear load is not the same as
the voltage. Typical examples of non-linear loads include rectifiers like power supplies,
discharge lighting, adjustable speed motor drives, ferromagnetic devices, DC motor
drives and arcing equipment.
Figure 2.4 Voltage and current waveforms for non-linear loads
‐200
‐100
0
100
200
0 50 100 150 200 250 300 350 400
voltage linear load current
‐200
‐100
0
100
200
0 50 100 150 200 250 300 350 400
voltage non‐linear load current
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The current drawn by non-linear loads is not sinusoidal but it is periodic meaning
that the current wave looks the same from cycle to cycle. Periodic waveforms were
described mathematically as a series of sinusoidal waveforms that have been summed
together. The sinusoidal components are integer multiples of the fundamental where the
fundamental, in the United States, is 60 Hz and Malaysia is 50 Hz. The only way to
measure a voltage or current that contains harmonics is by using a true-RMS reading
meter. If an averaging meter is used, which is the most common type, the error can be
significant.
Figure 2.5 Waveform with symmetrical harmonic components
Each term in the series referred as a harmonic of the fundamental. The third
harmonic would have a frequency of three times 60 Hz or 180 Hz. Symmetrical waves
contain only odd harmonics and un-symmetrical waves contain even and odd harmonics.
A symmetrical wave is one in which the positive portion of the wave is identical
to the negative portion of the wave. An un-symmetrical wave contains a DC component
or the load is such that the positive portion of the wave is different than the negative
portion. An example of un-symmetrical wave would be a half wave rectifier.