Aimi Shakira Yuseh ( CD 5278 )

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

ii

“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

xi

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


4.3(a) Comparison graph of real power to bus injection 37


4.3(b) Comparison graph of reactive power to bus injection 38


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


4.9(b) Comparison graph of reactive power from bus injection 52


4.10(a) Comparison graph of real power to bus injection 53


4.10(b) Comparison graph of reactive power to bus injection 53


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.

3

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.

4

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.

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Aimi Shakira Yuseh ( CD 5278 )