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REMOTE METER READING OVER 
POWER DISTRIBUTION LINES. 
THESIS PRESENTED 
BY 
K. GAMAGE 
SUPERVISED BY 
DR. J P KARUNADASA 
DR. DELEEKA DIAS 
DR A. RAN A WEE RA 
This thesis was submitted to the department of Electrical Engineering of the 
University of Moratuwa - Sri Lanka 
in partial fulfillment of the requirements for the 
Degree of Master of Philosophy 
Electrical Engineering Department u n i v . « . ^ 0 r M o n i . „ w , 
University of Moratuwa IlllffllllllllUIIIIIlllillll) 
Sri Lanka Iii II III IIII If III 
79294 
September 2003 
7 9 2 9 4 
DECLARATION 
The work submitted in this thesis is the result of my own investigations, except where 
otherwise stated. 
It has not already been accepted in substance for any degree, and also is not being 
concurrently submitted for any other degrees. 
Signed 
K. Gam age 
(Candidate) 
Signed Signed 
Dr. J P Karunadasa Dr. Dileeka Dias 
(Supervisor) (Supervisor) 
Del icated to 
my loving mother , e lder b ro ther 
and 
teachers 
who encouraged me 
f o r my education 
ABSTRACT 
The thesis presents the development of a simple technique for remote reading of utility 
meters using the low voltage power distribution network. 
Remotely reading electricity, gas and water meters have distinct advantages over 
traditional metering methods. Several communication technologies have been designed 
and implemented for this purpose using wireless techniques, telephone lines, power 
transmission and distribution lines. In this study, the last one has been selected as the 
basis for the development of a remote meter reading system applicable to Sri Lanka. 
Power line communication over low voltage distribution lines is a cost effective method 
for data transmission. But it is complex due to large number of branches, tapings, 
transformers, different line configurations etc., that are present in the distribution 
network. The main task of this research is to develop suitable techniques for transfer of 
data over this network. 
The basic concept of data transmission in this application is the change of voltage and 
current wave at the supply end and the load end respectively of the power system. A 
series of current pulses are generated representing the data to be transmitted from the 
consumer end. Similarly, a series of voltage pulses are generated at the supply end to 
represent the commands to be sent to the consumer. These current and voltage pulses are 
superimposed with the line current and the line voltage at the load end and the supply end 
respectively on the power line signal. 
The prototype system presented in this thesis shows simulation as well as experimental 
results relating to the data transmitter, and the software design for the communication 
subsystem interfacing the meter to the distribution lines. A series of measurements are 
also carried out to find a suitable time of the day for the data transmission. Associated 
problems such as harmonics generated due to the insertion of data and the effects of load 
changes in the distribution network are also discussed. 
m 
ACKNOLEDGEMENT 
The research for the Degree of Master of Philosophy was carried out at the Department of 
Electrical Engineering, University of Moratuwa, Sri lanka. 
I would like to acknowledge the support received under the Science & Technology 
Personnel Development Project SRI (SF) 1535 by the Asian Development Bank for the 
work described in this thesis. 
I would express firstly great thanks to the Department of Electrical Engineering, and the 
members of the Post Graduate committee specially, prof. J R Lucas and Prof. Mrs. N 
Ratnayake, for having accepted me to commence the research for two years time. 
I am deeply indebted to my former supervisor Dr A Ranaweera, who gave me this project 
proposal and confirmed it. He also supervised my research work and encouraged me to 
go ahead with my works during the first half of the research period. 
I must express my profound gratitude and sincere thanks to my supervisors Dr. Mrs. 
Dileeka Dias and Dr. J P Karunadasa whose guidance, encouragements and motivation in 
all the time of the research. They also provided constructive comments during my thesis 
time as well as the preliminary version of this thesis. I was great pleasure to conduct the 
work under their supervision. 
I must specially mentioned Mr. J D Leelasiri, Technical Officer in Electrical Machine 
Laboratory, University of Moratuwa. He provided me an invaluable support without any 
hesitation to collect data from Ceylon Electricity Board during day and night, to prepare a 
laboratory model and model transformers, to order and buy required items in-time and 
other technical supports. Therefore I would like to express my grateful thanks for giving 
his hands to success my research. 
I V 
The research has been supported by the Officers, in Ceylon Electricity Board for 
collection of on line data from Grid substation Ratmalana and Distribution substation, 
Katubedda. I am greateful to the staff members in CEB and LECO including Chief 
Engineers Mr D G Riency Fernando, Mr. S Bogahawatta, Electrical engineers Mrs. 
Amali , Mr Kusum Shanthi, Electrical Supirintendents Mr. JMDWR Jayawardana and 
Mr. Waruna Jayawardana. 
The contributions of the Technical Officers and the laboratory staff members in 
Electrical, Electronics & Telecommunication engineering departments specially, Mr. 
MWD Wasantha, Mr. J C P Wickramaratne, Mr J H J Perera and Mr. K A D S Somasiri 
are gratefully acknowledged. Specially I am obliged to my friends Chandani Ambepitiya, 
Nandaka Jayasekara, Bathiya Jayasekara, L Y C Amarasingha, D S Wikramanayake, 
Wasantha for making me a good environment at the University. 
V 
TABLE OF CONTENTS 
CHAPTER ONE INTRODUCTION 1 
t 1.1 Solutions of increase of electricity demand and its 
Consumers' in Sri Lanka 1 
1.2 Importance of remote metering 2 
CHAPTER TWO SURVEY OF POTENTIAL COMMUNICATION 
TECHNIQUES FOR REMOTE METER READING 4 
« 
2.1 Telephone based communication. 5 
2.2 Radio based communication. 6 
2.3 Power line carrier communication 7 
2.4 Distribution line carrier communication 9 
2.4.1 Low power radio frequency/power line carrier 
system (RF/PLC) 10 
* 
2.4.2 Power frequency communication (TWAC) 10 
2.4.3 Ultra Narrow Bandwidth PLC communication 11 
2.4.4 Low frequency signal transmission ... 11 
CHAPTER THREE PROPOSED DATA TRANSMISSION 
TECHNIQUE FOR RMR 12 
3.1 
3.2 
VI 
Data transfer concept. 12 
3.1.1 Outbound signal 12 
3.1.2 Inbound signal 14 
Basic communication system design overview 14 
3.2.1 Remote transponder Unit 14 
3.2.2 Communication channel 16 
3.2.3 Data collection Unit 16 
» 
3.3 Structure of data transmission system 16 
3.3.1 From Remote Transponder Units to the Primary 
Data Collection Unit 19 
3.3.2 From Primary Data Collection Units to Secondary 
Data Collection Units 19 
3.3.3 From Secondary Data Collection Units to Central 
Reading Unit. 21 
CHAPTER FOUR COMMUNICATION PROTOCOL 22 
CHAPTER FIVE. DESIGN AND IMPLEMENTATION OF RMR 
SYSTEM. 27 
5.1 Pulse Design. 27 
5.1.1 Modeling of an existing distribution system and 
construction of a prototype power distribution 
model 28 
5.1.2 Observation of pulse transmission and detection 
using computer simulation software 37 
5.1.3 Power line disturbances and recommended 
standards and safety limits of voltage 
and current 41 
5.1.4 Observation of existing disturbances on 
selected power distribution system 42 
* 5.1.4.1 Current Wave disturbances. 42 
5.1.4.2 Voltage wave disturbance. 42 
5.1.5 Theoretical studies on harmonic frequency 
of different pulse patterns 47 
5.1.5.1 Spectrum analysis of a rectangular 
% pulse signal 48 
vn 
5.1.6 Observation of pulse transmission, with the power 
line disturbances 51 
5.2 Suggested implementation of Transceiver hardware 57 
5.3 Software Design 60 
CHAPTER SIX. OBSERVATION AND RESULT 63 
CHAPTER SEVEN. CONCLUSION 65 
Annexes 
Appendix A 
Appendix B 
List of References 
» 
* 
vm 
• 
LISTS OF FIGURES 
Figure 3.1(a) Superimposed pulses with sinusoidal wave of 
Voltage/Current at the transmitter 13 
Figure 3.1(b) Detected pulses at the receiver 13 
Figure 3.2 Components of the Basic Communication System 15 
Figure 3.3 Functional Block Diagram of message exchanging 
System in between DCU and RTU 17 
Figure 3.4 Selected Distribution Line Diagram 18 
Figure 3.5 Structure of the data transmission system 20 
Figure 4.1 Exchanging messages between RTU and DCU 22 
Figure 4.2 A message block 23 
Figure 4.3 Communication Protocol at the Substation 24 
Figure 4.4 Communication Protocol at the Consumer End 25 
Figure 4.5 Structure of Outbound message 26 
Figure 4.6 Structure of Inbound message 26 
Figure 5.1a Simplified Load Distribution System from Ratmalana 
grid Substation to the Campus premises 33 
Figure 5.1b Line blocks of main distribution system in Figure 5.1a 34 
Figure 5.2a The front side of the Laboratory model Power 
distribution System 35 
Figure 5.2b The back side of the Laboratory Model Power 
Distribution System 36 
Figure 5.3 Current and Voltage pulses fed at the 400V load end 
And the 33 kV supply end respectively 38 
Figure 5.4 Voltage waveforms and their filtered outputs on 
distribution system after applying the voltage pulses 39 
Figure 5.5 Current waveforms and their filtered outputs on 
distribution system after applying the current pulses 40 
Figure 5.6a Feeder current at 33 kV side during daytime 43 
Figure 5.6b Feeder current at 33 kV side during nighttime 43 
Figure 5.7a Frequency spectrum diagrams of current wave at the 
substation during daytime 44 
Figure 5.7b Frequency spectrum diagrams of current wave at the 
substation during nighttime 44 
Figure 5.8 Harmonics in R, Y and B Phases of Voltage wave in 
33 kV line from 2 n d to 15 t h harmonics 46 
Figure 5.9 Square wave pulse 48 
Figure 5.10 Power Spectrum Density for Square shape pulses 49 
Figure 5.11 Power Spectrum Density for Sinusoidal shape pulses 50 
Figure 5.12 Frequency spectrum and filtered output of current wave 
At the 33 kV side of the substation during night time 52 
Figure 5.13 Frequency spectrum and filtered output of pulse wave 53 
Figure 5.14 Frequency spectrum and filtered output of resultant 
Current wave at the 33 kV side of the substation during 
Nighttime 54 
Figure 5.15 Frequency spectrum and filtered output of current wave 
at the 230V side of the distribution transformer 55 
Figure 5.16 Connection of microcontroller & associated electronic 
Components 58 
Figure 5.17 Architecture of 8051 microcontroller 59 
Figure 5.18 DC Power Supply 60 
Figure 5.19 Way of operation of microcontroller 61 
LISTS OF TABLES 
Table 5.1 Line parameters for different conductors in the system 29 
Table 5.2 Transformer details 29 
Table 5.3 General line Inductance and Capacitance values of HV 
conductors 30 
Table 5.4 Resistance, Inductance and Capacitance values for the 
distribution system 30 
Table 5.5 Design parameters for the model 32 
Table 5.6 Average values of harmonic components and THD of 
R, Y and B phases in 33 kV line at the substation 45 
Table 5.7 Pseudo Code 62 
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