DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEERING
FACULTY OF ENGINEERING
UNIVERSITY OF RUHUNA
INDUSTRIAL TRAINING REPORT SUBMITTED IN PARTIAL FULFILMENT OF
THE DEGREE OF BACHELOR OF SCIENCE IN ENGINEERING
3rd April 2017
CEYLON ELECTRICITY BOARD
(From 19th December 2016 to 10th March 2017)
BASNAYAKA W.B.M.C.M. (EG/2013/2151)
PREFACE
I had my training experience from 19th December 2016 to 10th March 2017 at Ceylon
Electricity Board (CEB). Here in this report I present the experience, knowledge, skills I had
during the training period.
The report contains three chapters. The first chapter contains an introduction to Ceylon
Electricity Board (CEB), company strategy and organizational structure. The second chapter
contains the training experience, information on power system of Sri Lanka and equipment,
project work and assignments that I involved during the training period. Next chapter
contains the management structure of Ceylon Electricity Board (CEB). And the summery
and conclusion were included in the last chapter.
I had a very successful training period and the experience and knowledge I got is very
valuable to my future career.
Basnayaka W.B.M.C.M
EG/2013/2151
Department of Electrical and Information Engineering,
University of Ruhuna.
i
ACKNOWLEDGEMENT
Knowledge is a great thing that repels the darkness of ignorance. Yet seeking the depths of
knowledge without limits can be disastrous. However, one alone cannot simply gain
knowledge without the gracious guidance of the teachers.
There are lots of people who have helped me towards the successful completion of my
Industrial Training. First of all, I would thank to University of Ruhuna and National
Apprentice and Industrial Training Authority (NAITA) for arranging industrial training for
undergraduates. Then I would like to thank Dr. J.M.R.S Appuhami the Director of the
Engineering Education Center (EEC), Faculty of Engineering, University of Ruhuna, for
arranging me this opportunity to have my training experience in Ceylon Electricity Board.
I sincerely thank Eng. Chandani Premarathne Training Officer (Internal Training) and staff
of Ceylon Electricity Board (CEB) for accommodating me as a trainee. I must greatly
appreciate operation engineers in Lakvijaya and Kotmale power plants, Training assistant
for giving me advices, sharing their knowledge and guiding me during the training period.
I wish to express my gratitude again to all those people who helped me towards the success
of my Industrial Training.
Basnayaka W.B.M.C.M
EG/2013/2151
Department of Electrical and Information Engineering,
University of Ruhuna.
ii
CONTENTS
1
Introduction to the Ceylon Electricity Board ................................................................ 1
1.1
1.1.1
Vision .............................................................................................................. 1
1.1.2
Mission ............................................................................................................ 1
1.1.3
History of Ceylon Electricity Board ................................................................ 2
1.1
2
Overview of The Company..................................................................................... 1
Organization Structure ............................................................................................ 2
Training Experiences- Technical ................................................................................... 5
1.2
Generation Division ................................................................................................ 5
1.2.1
Present Status of Ceylon Electricity Board ..................................................... 5
1.2.2
Mahaweli Complex Reservoirs and Power Stations ....................................... 7
1.2.3
Introduction to Kotmale Power Station ........................................................... 7
1.2.4
The Main Physical Components of the Kotmale Project ................................ 9
1.2.5
Introduction to Lakvijaya Power Plant .......................................................... 19
1.2.6
Component of Lakvijaya power Plant ........................................................... 20
1.2.7
Operation Process of the Lakvijaya Power Plant ........................................ 26
2.1.1
Auxiliary System of the Plant........................................................................ 27
2.1.2
Coal Storage Management techniques .......................................................... 28
2.2
Transmission Division .......................................................................................... 29
2.2.1
Transmission Network in Sri Lanka .............................................................. 29
2.2.2
Grid sub station.............................................................................................. 31
2.2.3
Biyagama Sub Station ................................................................................... 31
2.2.4
Component of A Grid Sub Station ................................................................ 33
2.2.5
Electrical Power Transformer ........................................................................ 33
2.2.6
Circuit Breaker .............................................................................................. 35
2.2.7
Isolator and Earth Switches ........................................................................... 37
2.2.8
Current Transformers .................................................................................... 38
iii
2.2.9
Potential Transformers .................................................................................. 38
2.2.10
Bus Bar .......................................................................................................... 39
2.2.11
Grid Substation Overloading and blackout ................................................... 40
2.2.12
Introduction to System Control Center .......................................................... 40
2.2.13
Present Situation of Frequency Control in Sri Lanka .................................... 41
2.2.14
Frequency Controlling Method Use in Sri Lanka ......................................... 41
2.2.15
Droop Characteristics of a Generator ............................................................ 42
2.2.16
Basic Principles of Power System Operation ................................................ 43
2.2.17
Black Out Situation in Sri Lanka ................................................................... 44
2.2.18
Under-Frequency Load Shedding .................................................................. 45
2.2.19
Operational Planning and Dispatch ............................................................... 46
2.2.20
Utilization of Hydro Generation .................................................................... 46
2.2.21
Software and Methodologies of System Control Center ............................... 46
2.2.22
Introduction to Transmission and Generation Planning in Sri Lanka ........... 48
2.2.23
Electricity Demand Forecast Method and Past Demand ............................... 49
2.2.24
Long Term Transmission Plan ...................................................................... 50
2.2.25
Introduction to Heavy Maintenance of Low Voltage Transmission Line ..... 51
2.2.26
Design of Transmission Tower ..................................................................... 52
2.2.27
Types of Transmission Tower ....................................................................... 53
2.2.28
Transmission Line Maintenance .................................................................... 54
2.2.29
Major Tools Used for Live Line Maintenance .............................................. 55
2.3
Distribution Division ............................................................................................ 57
2.3.1
Introduction to Distribution Division ............................................................ 57
2.3.2
Transmission Lines of Distribution Network ................................................ 58
2.3.3
Present Situation of LV Lines ....................................................................... 58
2.3.4
Item Use in Overhead LV Construction ........................................................ 58
2.3.5
Issues and Concerns to be solved in CEB’s Distribution System ................. 60
iv
3
Training Experience –Management............................................................................. 62
3.1
Management Systems of CEB .............................................................................. 62
3.2
Asset management ................................................................................................ 62
3.3
Personal management ........................................................................................... 62
3.3.1
Welfare Unit .................................................................................................. 63
3.3.2
Security Section ............................................................................................. 63
3.3.3
Training Branch ............................................................................................. 63
3.3.4
5S System ...................................................................................................... 63
3.4
Safety Management .............................................................................................. 64
3.4.1
4
Safety Precautions ......................................................................................... 64
Summary and Conclusion............................................................................................ 65
4.1
Summary ............................................................................................................... 65
4.2
Conclusion ............................................................................................................ 65
Abbreviation ........................................................................................................................ 67
Reference ............................................................................................................................. 71
v
LIST OF TABLES
Table 2.1: Training Schedule................................................................................................. 5
Table 2.2:Power Station of Mahaweli Complex ................................................................... 7
Table 2.3 :Specification of the Dam ...................................................................................... 9
Table 2.4: Specification of Turbine ..................................................................................... 11
Table 2.5:Specification Of Generator .................................................................................. 15
Table 2.6:Specification Of Main Transformer .................................................................... 16
Table 2.7: Specification Of Turbine .................................................................................... 21
Table 2.8: Generator Parameters in Puttalam Coal Power Plant ......................................... 22
Table 2.9:Auxiliary Power Consumption Of Lakvijaya Plant ........................................... 28
Table 2.10: Specifications Of Transformers Of Biyagama ................................................. 34
Table 2.11 Load Shedding Scheme in Sri Lanka ................................................................ 45
Table 2.12:Voltage Criteria ................................................................................................. 48
vi
LIST OF FIGURES
Figure 1.1:Ceylon Electricity Board Logo ............................................................................ 1
Figure 1.2:Organization Structure Of CEB ........................................................................... 4
Figure 2.1 :Generation capacity Mix in MW -2014 .............................................................. 6
Figure 2.2 Arrangement Of Mahaweli Complex Reservoir .................................................. 7
Figure 2.3:Kotmale Reservoir ............................................................................................... 8
Figure 2.4: Radial Gate Of Kotmale Dam Spillway .............................................................. 9
Figure 2.5:Surge Chamber of Kotmale................................................................................ 10
Figure 2.6: Kotmale Under Ground Power Station ............................................................. 11
Figure 2.7:Arrangement of Turbine..................................................................................... 12
Figure 2.8: Turbine Runner Of Kotmale Power Plant ......................................................... 13
Figure 2.9:Guide Vanes Of The Power Plant ...................................................................... 14
Figure 2.10:Actuator of Governor ....................................................................................... 16
Figure 2.11:Kotamle Switch Yard ....................................................................................... 17
Figure 2.12: One Breaker And A Half Scheme Bus Arrangement ..................................... 18
Figure 2.13:Lakvijaya Power Plant ..................................................................................... 19
Figure 2.14:Generator Of Lakvijaya Power Plant ............................................................... 22
Figure 2.15: Unit Auxiliary Transformer ............................................................................ 23
Figure 2.16:Gas Insulator Substation In Lakvijaya Power Plant ........................................ 25
Figure 2.17:Operation Process Of Coal Power Plant .......................................................... 26
Figure 2.18:Coal Yard Of Lakvijaya Power Plant .............................................................. 29
Figure 2.19: Sri Lankan Transmission Network ................................................................. 30
Figure 2.20:Biyagama Grid Sub Station ............................................................................. 32
Figure 2.21: Main Transformer Of Biyagama Sub Station ................................................. 33
Figure 2.22:Minimum Oil Circuit Breaker Re- Installation ................................................ 36
Figure 2.23:Isolaters In 220Kv Switch Yard ....................................................................... 38
Figure 2.24: Current Transformers ...................................................................................... 38
Figure 2.25:Diagram Of 220kv Transformer Bay Section .................................................. 40
Figure 2.26: Speed Droop Characteristics Of Kotmale Hydro Power Plant ....................... 42
Figure 2.27:Daily Load Curve ............................................................................................. 49
Figure 2.28 :33kv Transmission Tower............................................................................... 51
Figure 2.29:Part Of Transmission Tower ............................................................................ 52
Figure 2.30:Transmission Tower Construction In Badulla Area ........................................ 53
vii
Figure 2.31:Hot Line Maintenance In Transmission Line .................................................. 54
Figure 2.32:Hot Stick Use In Hot Line Maintenance .......................................................... 56
Figure 2.33 :Pin Insulator .................................................................................................... 60
viii
Chapter One
1
Introduction to the Ceylon Electricity Board
1.1
Overview of The Company
The Ceylon Electricity Board (CEB) is a government owned and controlled utility of Sri
Lanka that takes care of the general energy facilities of the island. The Ministry of Power
and Energy is the responsible ministry above the CEB. Ceylon Electricity Board (CEB),
established by an CEB Act No. 17 of 1969, is under legal obligation to develop and
maintain an efficient, coordinated and economical system of Electricity supply in
accordance with any Licenses issued.
Figure 1.1:Ceylon Electricity Board Logo
1.1.1 Vision
“Enrich life through power”
1.1.2 Mission
To develop and maintain an efficient, coordinated and economical system of electricity
supply to the whole of Sri Lanka, while adhering to our core values

Quality

Service to the nation

Efficiency and effectiveness

Commitment

Safety

Professionalism

Sustainability
1
1.1.3
History of Ceylon Electricity Board
Sri Lanka's first public electricity supply was made available in Colombo in 1895 by Messrs
Boustead Bros. The business was soon taken over by the United Planters Co., Who extended
it and in 1899 built the Colombo electric tramways. In 1902, the Colombo Electric
Tramways and Lighting Co. Ltd. was formed and provided electricity supply until 1927
when the Department of Government Electrical Undertakings (DGEU) was established to
control the utility, which had by then been purchased by the Government.
DGEU was succeeded in 1969 when the Ceylon Electricity Board (CEB), a statutory
corporation, was established on the 1st of November 1969 under the Act of Parliament No.17
of 1969. While CEB is a public corporation the 1969 CEB Act does not endow it with fully
autonomous powers and the government has reserved to itself a substantial role in important
policy matters and in particular tariffs, capital investment, borrowing and the appointment
of the Chairman and the General Manager. The conditions of service of all CEB staff are
subject to the government regulation.
In 1913, Devapura Jayasena Wimalasurendra (1874 –1953) gave his thoughts on the
construction of a small hydro power station at Black pool, between NanuOya and
NuwaraEliya, to supply electricity to the Nuwara Eliya town. In 1918, also he submitted a
project report titled 'Economics of Hydro Power Utilization in Ceylon' to the Engineering
Association to make his dream come true. Accordingly, the Laxapana hydro power scheme,
the construction of which started in 1924 was thus resumed in 1938 and done to the finish.
However, it was commissioned as the first hydro power plant of Sri Lankan history in
December 1950.
Between 1978 - 1985 under the Master Plan of Mahaweli Development Programme added
seven hydro power stations to the national grid with a total installed capacity of 810 MW
this can be considered as a great leap forward for electricity generation in Sri Lanka.
1.1
Organization Structure
The Ceylon Electricity Board is a state-owned vertically integrated organization handling
generation, transmission and distribution functions. CEB's organization structure was
designed by consultants, Urwick International Ltd., in the early 1970's.
There are seven divisions: the generation, transmission, distribution and operation,
distribution development, commercial, headquarters, and finance manager divisions, under
the board members such as the Chairman and General Manager. Though CEB has been
established as an independent organ, executives are to be assigned by the Ministry of Power
and Energy, and approval by the Government is required for investments and setting tariffs.
2
CEB is a corporate body governed by a seven-member Board; members serve a five-year
term and may be reappointed. Board members are appointed by GSL, four with experience
in either engineering, commerce, administration or accountancy, and the others representing
local authorities, industry and the Ministry of Finance and may be removed at any time. The
Chairman is appointed from amongst the Board members. The organization chart of CEB is
shown in the Figure 1.2.
3
Figure 1.2:Organization Structure Of CEB
4
Chapter Two
2
Training Experiences- Technical
I had my second industrial training experience from 19th December 2016 to 10th March
2017 at the Ceylon Electricity Board (CEB) and it is the largest electricity company in Sri
Lanka. At the beginning of my industrial training programme I was reported to the office of
the Deputy General Manager (Training), Piliyandala and I got the training schedule for threemonth training period. Schedule of In-plant training programme in different branches and
units of CEB is shown in the table 2.1 below.
Table 2.1: Training Schedule
Division
Generation
Transmission
Place Of Training
Duration
From
To
Lakvijaya Power Station
13.02.2017
09.02.2017
Kotmale Power Station
27.02.2017
10.03.2017
Transmission Operation and
30.01.2017
09.02.2017
System Control Center
16.01.2017
20.01.2017
Transmission And Generation
23.01.2017
27.01.2017
Project And Heavy Maintenance
02.01.2017
13.01.2017
Distribution Division (Southern
20.12.2017
30.12.2016
Maintenance
Planning
Distribution
Province)
1.2
Generation Division
1.2.1 Present Status of Ceylon Electricity Board
Since 1980s, Sri Lanka has been facing a continuously increasing electricity demand due
to population growth, increase in electrification level, and socioeconomic development.
By the end of 2014, 5.4 million consumers have been served by the Sri Lankan power
sector and the total electricity demand of the Power Supply Performance country has
grown to 12,357 GWh during 2013 compared to 587 GWh in 1969.Also, Electricity
generation in Sri Lanka is primarily run by hydro power and thermal heat, with sources
such as photovoltaics and wind power in early stages of deployment.
5
Hydroelectricity has played a very significant role in the national installed power capacity
since it was introduced in the 1950s, with over 50% of the total grid capacity met by
hydroelectricity in 2000–2010.
Sri Lanka has two main hydro power complexes consisting of several power plants in each.
These two main hydro power complexes are the Laxapana complex and the Mahaweli
complex. Laxapana complex is based on the Kelani river while Mahaweli complex is based
on Mahaweli river. In addition, there are two independent large scale hydro power stations,
namely Samanalawewa and Kukule Ganga while small scale power plants such as
Inginiyagala and Uda Walawa are also generating hydropower using their respective
reservoir storages. For administrative purposes, these isolated hydropower plants are
grouped together as a single complex identified by the CEB as the ‘Other Hydro’ Complex.
Figure 2.1 :Generation capacity Mix in MW -2014
Details of the existing a hydro system are given in
appendix 1 and the geographical
locations of the Power Stations are shown in the appendix 1.
As of 2015, 1,464 MW of the total thermal installed capacity was from state-owned fossil
fuel power stations: 900 MW from Lakvijaya, 380 MW from the state-owned portion of
Kelanitissa, 160 MW from Sapugaskanda, and 24 MW from Uthuru Janani. The remaining
641 MW of the installed thermal capacity are from six privately owned power stations
Details of the existing a thermal system are given in appendix 1.
6
1.2.2
Mahaweli Complex Reservoirs and Power Stations
The Mahaweli Hydro power complex is main hydro power complex in Sri Lanka.
Figure 2.2 Arrangement Of Mahaweli Complex Reservoir
It consists of seven major power stations which has an installed capacity of 810 MWs. Upper
Kotmale, Kotmale, Victoria, Randenigala, Rantambe, Ukuwela, Bowatenna and Nilambe
are major power stations coming under Mahaweli complex, each station has capacities as
shown below table 2.2.
Table 2.2:Power Station Of Mahaweli Complex
Name of Power station Number of Units
Capacity of a
Total Capacity of
Unit
Power Plant
Kotmale
3
67
201
Victoria
3
70
270
Randenigala
2
61
122
Randambe
2
24.5
49
Ukuwela
2
20
40
Bowatenne
1
40
40
Nilambe
2
1.66
2.32
Upper Kotmale
2
75
150
1.2.3 Introduction to Kotmale Power Station
The kotmale dam is a large hydroelectric and irrigation dam in Sri Lanka. Also, it is one of
five major head work projects being undertaken under the accelerated Mahaweli Ganga
7
Scheme. It is the most upstream of these projects and develops the hydro potential of a major
right bank tributary of the Mahaweli Ganga, the Kotmale Oya. The Kotmale project was
mainly for the development of hydro power and the regulated discharge from the reservoir
to increase the flow diverted at the Polgolla barrage into the proposed Moragahakanda
reservoir for augmenting the irrigation suppled in systems. The reservoir would reduce flood
peaks and their frequency, thus alleviated the floods in the Gampola area below it.
Figure 2.3:Kotmale Reservoir
The water impounded by the reservoir would be conveyed through an underground water
conductor system to an underground power station located at about 7.2 km. (4.5 miles) from
the dam for generation of electric power. After power generation, this water will be
discharged through the outfall into the Mahaweli Ganga at the Atabaghe Oya confluence. In
addition to the generation of power, the regulated water will improve the pattern of inflows
of the Mahweli Ganga at the existing Polgolla diversion dam. This will firm up the power
benefits from Ukuwela power station and serve to increase the irrigation water supplies from
the Bowatenne dam. Almost all of the water stored in this reservoir is used to supply water
for irrigation demand along the Amban River basin. However, the more electrical energy is
generated by operating the reservoir near the full supply level with the higher effective head
and turbine efficiency. In this regard, this reservoir is normally operated at close to the full
supply level except when the water is released for irrigation.
8
1.2.4 The Main Physical Components of the Kotmale Project
I.
Dam
The catchment area of the river at the dam site is 544 square kms and the dam is a thick earth
core rock fill structure with 87m high and 600m long. These is other specification of
Kotamale Dam.
Table 2.3 :Specification of the Dam
Top water level (TWL)
703m – MSL
Maximum flood level
704.3m –MSL
Minimum operation level (MOL)
665m – MSL
Gross storage up to TWL
174 x 106 m3
It has a chute spillway with a capacity of 5500m3/Sec consisting of 3 radial gates
14x15m.Daiagram of radial gate is shown figure 2.4.
Figure 2.4: Radial Gate Of Kotmale Dam Spillway
II.
Intake Gates
These are the gates built on the in outside of the dam. The water from the reservoir is released
and controlled through these gates. These are called inlet gates because water enters the
power generation unit through these gates. When the control gates are opened the water
flows due to gravity through the penstock and towards the turbines.
III.
Tunnel and Penstock
9
Low pressure tunnel with diameter 6.2 m is totally 6954m long with a maximum capacity of
113.3m3 /sec & creates a 65.2m head. Penstock is a high pressure tunnel between the surge
chamber and the power house. It is 120m long & it creates a 105.9m head. The structural
design of the penstock is same as for any other tunnel expect it has to bear high pressure on
the inside surface during sudden decease in the load and increase in the load. Also, penstocks
are made of steel with circular 5.55-4.80m diameter and equipped with the head gates at the
inlet which can be closed during the repair of the penstocks, a sufficient water head should
be provided above the penstock entrance in the surge chamber to avoid the formation of
vortices which may carry air in to the penstock and resulting in lower turbine blade
efficiency.
IV.
Surge Chamber
The main function of 143 m height surge chamber is to reduce the water hammering effect.
When there is a sudden increase of pressure in the penstock which can be due sudden
decrease in the load demand on the generator. When there is sudden decrease in the load, the
turbine gates admitting water to the turbine closes suddenly owing to the action of the
governor. This sudden rise in the pressure in the penstock will cause the positive water
hammering effect. This may lead to burst of the penstock because of high pressures.
Figure 2.5:Surge Chamber of Kotmale
When there is sudden increase in the load, governor valves open and accepts more water to
the turbine. This results in creation of vacuum in the penstock resulting into the negative
water hammering effect. Therefore the penstock should have to withstand both positive
water hammering effect created due to close of governor valve and negative water
10
hammering effect due to opening of governor valve. In order to protect the penstock from
these water hammering effects, surge chamber is used in Kotmale power station.
V.
Power Station
Kotmale power
is underground power station with fully remote control system with
automatic frequency control operation. The design and manufacture of the Francis turbine
and generators for the Kotmale power station were done by KAMEWA Company and ASEA
Company. Since the 3×67 MW vertical Francis turbine and 3×9000KVA vertical
synchronous generator for this power station are the largest capacity machine in Sri Lanka
expect for Victoria power station.
Figure 2.6: Kotmale Under Ground Power Station
VI.
Turbine
The turbine is a vertical-shaft, single-runner Francis type with steel spiral case and elbow
type draft tube.
Table 2.4: Specification of Turbine
Number of Unit
Three
Type
Vertical Francis turbine
Speed of Rotation
375 rev/min
Head
Rated-201.5m
Maximum-231m
Rated output
67MW
Rated discharge
35m3/s
11
Figure 2.7:Arrangement of Turbine

Main Inlet Valve
Main inlet valve is the primary control for entry water to turbine and is the principle
protection for station. The main inlet valve is of the rotary type with double sealing to allow
the service seal to be examined or replaced without emptying pipe line.

Spiral Casing
These machines have vertical shafts. The fluid enters from the penstock to a spiral casing
which completely surrounds the runner. This casing is known as scroll casing or volute. The
cross-sectional area of this casing decreases uniformly along the circumference to keep the
fluid velocity constant in magnitude along its path towards the guide vane. Also, it is
manufactured of steel welded plate.

Turbine shaft
The turbine shaft is a common shaft with generator shaft and is directly connected to rotor
center of the through the trust support. The lower turbine shaft flange is connected to
12
runner. The shaft is hollow bored to diameter 150mm through its entire length and has an
integrally cast color to from the side bearing surface.

Runner
Even through this machine is a large capacity with a high speed machine, a fabricating
welded runner is partial casting having a better finishing profile of the runner blades than
the whole carbon steel casting runner. Diameter of runner is 2.05 m and speed of runner is
375r/min.
Figure 2.8: Turbine Runner Of Kotmale Power Plant

Draft Tube
The draft tube is a conduit which connects the runner exit to the tail race where the water is
being finally discharged from the turbine. The primary function of the draft tube is to reduce
the velocity of the discharged water to minimize the loss of kinetic energy at the outlet. This
permits the turbine to be set above the tail water without any appreciable drop of available
head. This turbine has Simple elbow type draft Tube and it consists of an extended elbow
type tube.
13

Guided Vane
Guided vans levers, links operating and sever motors are the principle parts of guide vans.
The turbine gates comprise 24 guide vanes of steel. The vertical faces of adjacent vanes are
connecting with each other when turbine is closed are accurately machine to prevent leakage.
Figure 2.9:Guide Vanes Of The Power Plant
The top of the upper stem of each guide vane is fitted with a cast steel lever and a gate lever
which is connected to operating rings by two plate steel links and ping. The connection
between stop lever and vane lever is by an adjustable friction joint. The friction joints protect
the vital parts of the turbine from diagram it some obstruction should prevent closure of the
gate.
VII.
Generator
The generator is a vertical-shaft, semi- umbrella type three-phase synchronous brushless
machine with AVR. Its rated continuous output is 90 MVA and has a lagging power factor
of 0.85. The winding of the generator rotor and stator should have Class-F epoxy insulation.
The stator windings are star connected and consists of identical single turn diamond lap coil
with full class “F” insulation arranged in open slots with two coil sides per slot.
Transposition of the standard forming a conductor is made outside the slots. The neutral ends
are brought out to separate terminals. Stator core is built up of high-grade non ageing silicon
steel punching, insulated on both sides with a heat resisting varnish.
Generators are usually ventilated on the closed circuit system in which the same air is
continually recirculated and passes through water cooling units. The water supply for both
oil and air coolers can readily be drawn from the turbine casing, thorough reducing valves
and strainers, so that it flows automatically when the main inlet valve opens. When water
14
head is high it is more economical to pump from the tail race/draft tube. Each turbine may
then have its own pump, generally with one standby common to all units
Table 2.5:Specification Of Generator
Rated Power
90MVA
Number of Units
3
Power factor
0.85
Rated speed
375 r/min
Runaway speed
725 r/min
Phase
3
Frequency
50Hz
Excitation
Voltage
220V
Current
1250A
Stator
F
Rotor
F
Insulation
VIII.
Governor system
This is the speed/load control of turbine and governor is the main controller in which the
governor adjusts the flow of water through the turbine to balance the input power with
the load. With an isolated system; the governor controls the frequency. In interconnected
system, the governor may be used to regulate the unit load and may contribute to the
system frequency control.
Electro-mechanical governor with speed and power control section and mechanical
hydraulic actuator sections are now generally employed. Speed power control section
and hydraulic actuator sections may be installed in separate locations. Governors are
designed to regulate the speed and thereby the loading on the unit within a desired range
by increasing or decreasing the amount of water supplied to the turbine runner. Turbines
are fitted with gate limiters which are can be remotely controlled. The gate limiter is used
for speed no load setting; desired control setting and over load of generators. The gate
limiter adjustment usually extends down to zero and thus affords a means for remote
stopping and starting at a safe and controlled rate.
15
Figure 2.10:Actuator of Governor
IX.
Main Transformer and Switchyard Equipment
Three main transformer units are installed in the transformer cage next to the control room.
The main features of the power transformer are as follows:
Table 2.6:Specification Of Main Transformer
Type
Single phase power transformer with off
circuit Tap changer
Rated frequency
50Hz
Rated power
30000KvA
Rated Voltage
Primary side
13.8Kv
Secondary side
220Kv
Primary side
1499A
Secondary side
1575A
Rated current
Bank connection symbol
YNd11
Type of cooling
ONAN/ONAF
Kotmale switch Yard is the main grid station in the transmission network of Sri Laka which
was constructed under Mahawali transmission Project in 1984. Mainly, it is a 220K outdoor
16
substation (air insulated), consist four 220Kv double circuit lines come from Biyagama,
Anuradapura, Victoria and Upper Kotmale substations.
Figure 2.11:Kotamle Switch Yard
There are three main 220/13.8kV three winding auto transformer with rating 90MVA each.
220 kV switchgear, in a one breaker and a half scheme bus arrangement, for six transformers
bays.one breaker and a half is a compromise between double bus bar scheme and the double
circuit breaker scheme. This scheme improves the reliability and flexibility because, even in
case of loss of complete bus bar there is no disruption in the power supply of the feeders.
17
Figure 2.12: One Breaker And A Half Scheme Bus Arrangement
X.
Electrical Auxiliary
Following electrical auxiliary system are provided and their control incorporated in the
control system.

Auxiliary Power AC System
This includes auxiliary transformers and switchgear for the auxiliary.in Kotmale power
house auxiliary power get though the earthling transformer. Also there are 400V in door
substation for auxiliary.

DC System and Batteries
This includes DC batteries and switchgear for control, emergency lighting, generator
field flashing etc.
18
1.2.5 Introduction to Lakvijaya Power Plant
The plant is located approximately 100m inland from the shoreline near the villages of
Narakkalli and Penaiyadi on the Kalpititya peninsula in the Puttalam district of the North
Western Province. First 300 MW coal fired power plant of the Puttalam Coal Power Project
which commissioned in 2011 is now in commercial operation. Peoples Republic of China
has provided a concessionary loan for the implementation of the project.
Figure 2.13:Lakvijaya Power Plant
Transmission line of 115 km from Norochcholai to Veyangoda Grid Substation and
associated infrastructure, coal unloading jetty with cranes and coal unloading barges and
tugs, stationed at Norochcholai power plant were also included in addition to the 300 MW
power plant included in the Phase I of the Project. Under second
and
third phases (2x300
MW) of 300 MW coal fired power plants and transmission line of 98 km from Norochcholai
power plant site to Anuradhapura, Anuradhapura Grid Substation, New Chilaw Grid
Substation. Constructions of the second 300 MW power plant was completed in February
2014 and third 300 MW unit were completed in August 2014. This power plant has generated
1,404 GWh Units in 2012, 1,469 GWh Units in 2013, 3,202 GWh Units in 2014 and 3,328
GWh Units by end of August 2015.
19
1.2.6 Component of Lakvijaya power Plant
I.
Boiler
Boiler is the main part of the power plant. The purpose of the boiler is to boil water to
produce steam. In actual, the boiler is made of several mechanical as well as electrical parts
like boiler drum, de-aerator, economizer, water wall tubes, furnace, super-heaters etc. The
300MW unit boiler of Puttalam coal-fired power plant project is subcritical, one-stage reheat
and natural circulation drum boiler, which adopts balance draft and tangential firing, fired
bituminous coal.
BMCR (boiler maximum continuous rating) condition is the design condition, the maximum
Continuous steam output is 1025t/h; when unit electric load is 300MW the rated steam
output is 964t/h.
A pulverized coal-fired boiler is an industrial
that generates thermal energy by
burning pulverized coal (also known as powdered coal or coal dust since it is as fine as face
powder in cosmetic makeup) that is blown into the firebox.
The basic idea of a firing system using pulverized fuel is to use the whole volume of
the furnace for the combustion of solid fuels. Coal is ground to the size of a fine grain, mixed
with air and burned in the flue gas flow. Coal contains mineral matter which is converted to
ash during combustion. The ash is removed as bottom ash and fly ash. The bottom ash is
removed at the furnace bottom.
II.
Water Treatment Plant
Sea Water is treated to remove the mineral contents as these minerals are harmful for boiler
parts because presence of minerals may lead to corrosion.
III.
Coal Handling Plant
The coal is the main fuel in a coal fired thermal power plant. First of all the coal is kept ready
in CHP (Coal handling plant) to send it before the boiler because it may content some
impurities as per their grade.
IV.
Ash Handling Plant
Here the final ash coming out from ESP is collected. This ash can be used to make bricks,
cement etc.
V.
Chimney
The flue gas coming out from the plant side is thrown away by this giant pipe like design.
chimney of Puththalam coal power plant is 200m height.
20
VI.
Control Room
The control room is equipped with a number of computers with smart visual simulating
software to control the whole power plant machines by giving commands.
VII.
Turbine
The turbine is a rotating mechanical metallic part to generate mechanical torque to drive the
heavy turbo generator by using pressure of steam.300Mw boiler height about 70m.It is sub
critical, single reheat, tandem compound, two casing double exhaust condensing steam
turbine.
Table 2.7: Specification Of Turbine
VIII.
Rated output
300MW
Main steam pressure
16.7Mpa
Reheat temperature
538°C
Main steam temperature
538°C
Regenerative stage
8 stage
Generator
This is a very important rotary electrical part where the plant output in the form of voltage
and current are produced. The function of generator is to convert the mechanical energy of
turbine to the electrical energy. Almost the generators are directly shaft coupled with the
turbine. The type of turbo-generator is a 3-phase non-salient pole synchronous generator
driven by a steam turbine. The rated rotating speed of the generator is 3000 r/min; frequency
is 50 Hz.
21
Figure 2.14:Generator Of Lakvijaya Power Plant
The rotation direction of the generator is clockwise when we observe it from driven end. The
excitation is provided by static thyristor system. The generator adopts the cooling type of
“W(water) and H(hydrogen)”. Stator coil adopts water internal cooling, rotor coil is
hydrogen internal cooled, stator core and the end components is hydrogen surface cooled.
Collector ring is cooled by air.
Table 2.8: Generator Parameters In Puttalam Coal Power Plant
Apparent power
353MVA
IX.
Active power
330MW
Maximum continuous output (MCR)
332MW
Rated power factor
0.85(lag)
Rated stator voltage
20000V
Rated stator current
10190A
Exciting voltage (design date)
365V
Exciting current (design date)
2642A
Efficiency (design date)
98.9%
Frequency
50 Hz
Rotate speed
3000r/min
Number of phases
3
Stator winding connection type
YY
Power Transformers in Puttalam Coal Power Plant
22

HV transformer
The Generator Transformer (GT) type is three phase power transformer, technical
specification is as follows: 50Hz, forced-oil forced-air cooled (ONAN/ONAF/ODAF),
outdoor type transformer with two copper windings, with On Load Tap Changer. The rated
capacity is 360 MVA, the HV sided rated voltage is 220kV/20 kV.
The Unit auxiliary transformer (UAT) type is three phase transformer, technical
specification is as follows: 50Hz, forced-air cooled (ONAN/ONAF), outdoor type
transformer with split windings without on load tap changer, which rated at 31.5 MVA (LV
winding). The rated voltage is 20kV/6.3 kV.
Startup/standby transformer
The Start/standby transformer (SST) type is a three phase transformer, technical
specification is as follows: 50Hz, forced-air cooled (ONAN/ONAF), outdoor type
transformer with split windings (with on load tap changer), which rated at 31.5 MVA (LV
winding). The rated voltage is 220kV/6.3 kV.
Figure 2.15: Unit Auxiliary Transformer
X.
Auxiliary System of Generator

The auxiliary system is closely related to the generator operation. It affects normal
operation and output of the generator directly.
23

The auxiliary system of generator is composed of the hydrogen and water cooling
system, the temperature monitoring system, the excitation system, and the oil system
and etc. The simple intro of the temperature monitoring system is as follow:

Operation temperature of every part of the generator should be monitored during
normal operation. The monitored positions are stated as follows: the stator winding,
the stator core, the cold H2 area, the warm H2 area and the oil and etc. Temperature
measuring units are buried at these positions and connected with the temperature
monitor through wires.
XI.
Automatic Synchronizing Device
The 300MW Generator Units is equipped with automatic synchronous detectors. Before
connected to the power grid, excitation system of the generator should be put into operation
and the voltages at two sides must meet with the requirements of synchronization. The
phases, the frequency, and the phase sequences are all same with the system.
XII.
Composition and Function of Excitation System
The generator is equipped with the excitation system of the type UNITROL manufactured
by ABB Corporation. A static excitation system regulates the terminal voltage and the
reactive power of the synchronous generator by direct control of the field current using
thyristor converters. The entire system can be divided into four major function groups.

Excitation transformer

Excitation Modules with Control Electronics

Thyristors' Converter units

Field flashing and field suppression equipment
In static excitation systems, the excitation power is taken from the generator terminals. The
field current of the synchronous generator flows through the excitation transformer, the field
circuit breaker -and the power converter (thyristor converter). The excitation transformer
reduces the generator terminal voltage to the required input voltage for the thyristor
converter, provides the galvanic isolation between the generator terminals and the field
winding. The power converter (3 sets) converts the AC current into a controlled DC current
If. At the beginning of the unit starting, the field flashing energy is derived from the residual
generator terminal voltage, if the residual cannot meet with requirements; it will derived
from the auxiliary power supply. As soon as 10 to 20 V at the input of the thyristor converter
are reached, the thyristor converter and control electronics are ready for the normal operation
and a soft-start sequence takes place. After synchronizing with the network, the excitation
24
system can operate in AVR mode regulating the generator terminal voltage and reactive
power.
XIII.
Switchgear and Substation
Mainly, it is a 220kv indoor substation consist four 220kv double circuit line come from
Veyangoda and Anuradapura substation. Gas-insulated high-voltage switchgear (GIS) is a
compact metal encapsulated switchgear consisting of high-voltage components such as
circuit-breakers and disconnectors, which can be safely operated in confined spaces.
Figure 2.16:Gas Insulator Substation In Lakvijaya Power Plant
XIV.
Electro Static Precipitator
In order to save environment from harmonic micro particles as well as large dust particles,
the dust in the form of fly ash are caught here and settled down. The ESP (Electro static
precipitator) is an electrical device to produce high voltage corona effect to charge the dust
particles. When passing through the high voltage electrostatic fields, dust particles in the gas
will be charged by colliding with positive ions, negative ions and electrons or in the ion
dispersion movement. The particles with electrons and ions will then move, under the
influence of the electric force, toward and later accumulate on the electrodes of opposite
polarity. By means of rapping, the layer of dust particles on the electrodes will be dislodged
into the bottom hoppers. Practice shows that the higher the strength of electrostatic field, the
more effective an ESP will be, and that it is preferable to have an ESP operating with
negative corona. Therefore, our ESP is designed in the structure of high voltage negative
corona.
25
1.2.7 Operation Process of the Lakvijaya Power Plant
Figure 2.17:Operation Process Of Coal Power Plant
Consider the operation process of the power plant simply which runs according to the
Regenerative, Reheat Rankine Cycle. Pulverized coal from coal pulverizers is sent to the
boiler and superheated steam is generated in the boiler by means of heat of fired coal.
Superheated steam is initially sent to the High pressure turbine and turbine exit steam is sent
again to the boiler for the purpose of reheating. Reheated steam is sent to the intermediate
pressure turbine and that exit steam is directly sent to the law pressure turbine. All the three
turbines are coaxially connected as a single shaft and the electricity generator is also
connected to that shaft itself. The outlet of the LP turbine is directed to the condenser.
Condensate from the condenser is pumped to the condensate polishing unit by using a
condensate pump. Polished condensate from the polishers is sent to the LP heater no 8 and
then to no 7, 6 and 5 respectively. Heated condensate from LP heaters is sent to the deaerator and condensate from de-aerator is pumped to high pressure heater no 03, and then to
no 02 and 01 HP heaters using two boilers feed pumps. (After the Feed pumps the condensate
is named as feed water.)
In LP and HP heaters, condensate is indirectly heated using steam extracted from different
levels of different turbines. De-aerator is a mixing type heat exchanger having both functions
of heating of condensate and expelling dissolve oxygen from the condensate. Feed water
from HP heater 01 is sent to the economizer in boiler and is heated using flue gas and then
26
it is sent to boiler drum. Then the condensate is circulated from the boiler drum to down
comers and then to water wall tubes and then again to boiler drum. Qualified dry saturated
steam is separated from the boiler drum and then flown to super-heater panels. Superheated
steam from super heater panels is sent to the HP turbine and the steam cycle is completed.
2.1.1 Auxiliary System of the Plant
The electric generator which has coaxially coupled to the steam turbine tandem produces the
electric power and this power is defined as Gross Power output of the Power plant. For the
various electric motor driven equipment and other electrical appliances, a significant fraction
of that gross power output should be spent and that amount of that electricity is called as the
house load or auxiliary power consumption or internal electricity demand of the power plant.
In Lakvijaya Power station, about 30 MW out of 300MW of generator gross power output
is consumed as the internal electricity demand. Then the net power output (difference
between gross power output and internal electricity demand) will be nearly 270 MW.
Auxiliary power consumption of different sections of the power plant can be identified as
follows. All the sub system of the power plant can be classified into four main systems as
Turbine Plant, Boiler Section, Coal Handling system and Balance of Plant system (BOP).
Turbine section including Boiler Feed Water Pumping system (BFP), the Condensate
Extraction Pumping system (CEP), Main Cooling Cater system (MCW), Close Cycle
Cooling Water system (CCCW), Open Cycle Cooling Water system (OCCW) and other
related sub systems having several high capacity pumps such as CEP, Booster pumps and
main BFP, MCW pumps, OCCW pumps, CCCW pumps etc. Consumes about 14.9 MW
from the 30MW of internal electricity demand.
Out of that power, BFP consumes about 9.6 MW to pump the feed water from de-aerator to
boiler drum from suction pressure of 0.9 mpa to discharge pressure of 22 mpa. Other than
that, Main cooling water system consumes about 3.2 MW for two-mixed flow vertical type
MCW pumps having a flow capacity of 18m3/s, for cooling the condenser. Coal handling
system having several unloading cranes, stacker-reclaimers, conveyer belts, coal crushers
and pulverizes etc. Consumes about 1.1MW from internal electricity demand.
27
Table 2.9:Auxiliary Power Consumption Of Lakvijaya Plant
Equipment
Power
Consumption
Percentage from internal
(MW)
electricity demand
Cranes
0.80
2.67%
Conveyor belts
1.05
3.50%
Coal crushers
1.00
3.33%
Pulverizers
1.35
4.50%
Pumps
18.50
61.66%
Fans
4.85
16.17%
Compressors
1.10
3.67%
BOP section including water treatment system, Chlorination plant, Hydrogen generation
plant, Chillers for HVAC, Air compressors and fire & service water pumps etc consumes
about 3.6 MW from the auxiliary power consumption. Out of that power, water treatment
system including Sea water pre-treatment plant, Sea water desalination plant, Boiler make
up water treatment plant and consumes about 1.8 MW for the number of different types of
pumps and other appliance which are involved with this system. About 1.75MW of auxiliary
power goes to air compressor system chillers having a large number of compressors and chill
water pumps, compressors etc. Air and flue gas handling system of boiler, including various
no of high capacity fans, pumps and other equipment such as, Forced Draft Fans (FDF),
Induced Draft Fans (IDF), Primary Air Fans (PAF), Seal Air Fans, Air Pre-Heaters (APH),
Absorber pumps, Booster fan and Aeration Fans for Flue Gas De-sulpurizer (FGD) etc
consumes about 7.7 MW from the auxiliary power consumption.
Other than that various electrical equipment in the power plant including lifts, lights, small
pumps and fans, tools and equipment used for maintenance works, office equipment etc also
poses a significant amount of power from the internal electricity demand.
2.1.2 Coal Storage Management techniques
The existing conveyer system arrangement consists of mainly 8 numbers of belts. The
capacities of stacking (Storing in compacted manner) and reclaiming coal (for the use in
boiler) is indicated for each conveyer belt in the following diagram. Belt 09 construction and
28
Stacker Reclaimer 03 is yet in proposal stage. Earlier, prior to coal yard extension the coal
yard is of total capacity was 989,531 MT. With the extension of the coal yard in future the
coal storage capacity is increased up to 1.4 million MT.
Figure 2.18:Coal Yard Of Lakvijaya Power Plant
2.2
Transmission Division
2.2.1 Transmission Network in Sri Lanka
The electricity transmission network in Sri Lanka is solely owned and operated by Ceylon
Electricity Board (CEB). CEB is responsible for the safe, secure and efficient operation of
the electricity transmission in Sri Lanka. The transmission network is operated at 220kv and
132kv to transport electricity from generation points to distribution bulk supply points.
Prior to 1980s, the Ceylon Electricity Board (CEB)’s transmission system was composed of
132Kv and 66Kv lines which had been developed in coordination with growth in demand
and development of hydroelectric power project for delivering power to Colombo and other
region.
The Sri Lankan transmission system comprises 794 kilometers of 220kV overhead line
circuits, 3102 kilometers of 132kVoverhead line circuits, 8 of 220kV Grid Substations and
55 of 132kV Grid Substations and is shown below.
29
Figure 2.19: Sri Lankan Transmission Network
220kV transmission system is mainly used to transmit power from Mahaweli complex hydro
plants to main load center around Colombo through Kotugoda, Pannipitiya and Biyagama
grid substation.132kV transmission network is used to interconnect most of grid substation
and to transfer power from other power station. In 2011 the coal plants of Puttalam connected
to the 220kV system by 100km long transmission line to new Anuradapura and a 70Km long
30
transmission line to Chilaw grid substation. The 220Kv transmission line of BiyagamaKotugoda, Kotugoda-Veyagoda, Veyangoda-New Chilaw, New Chilaw- Puttalam Coal,
Puttalam Coal-New Anuradpura,New Anuradhapura-Kotmale and Kotmale-Biyagama
create the 220Kv ring and act as backbone of the system. At present around 2400Mw is
connect to the 220kv and around 1400MW connected to 132Kv network. Also, the
transmission network consists of overhead transmission lines with ACSR conductors
mounted on steel towers including a 13km length of 132kV underground cable network
within the Colombo City supply.
2.2.2 Grid sub station
A substation is a part of an electrical generation, transmission, and distribution system.
Substations transform voltage from high to low, or the reverse, or perform any of several
other important functions. Between the generating station and consumer, electric power may
flow through several substations at different voltage levels. A substation may
include transformers to change voltage levels between high transmission voltages and lower
distribution voltages, or at the interconnection of two different transmission voltages. Substation has many components (e.g. circuit breakers, switches, fuses, instruments etc.) which
must be housed properly to ensure continuous and reliable service. According to
constructional features, the sub-stations are classified as: a

Indoor sub-station

Outdoor sub-station

Pole-mounted sub-station
2.2.3 Biyagama Sub Station
Biyagama substation is the main receiving station in the transmission network of Sri Laka
which was constructed under Mahawali transmission Project in 1984. Mainly, it is a
220Kv/132Kv/33Kv outdoor substation consist four 220kV double circuit line come from
Kotugoda,Kotmale,Kelanitissa and Pannipitiya substations and two 132Kv double circuit
line come from switch yard of Sapugaskanda power station. There are two main 220/132kV
three winding auto transformer with rating 250MVA each. Also it consists 33Kv switch yard
which is connect to 132Kv bus bars through 132kv/33kv step down power transformer. 220
kV switchgear, in a double bus bar arrangement, for four transmission circuits (with space
for six more), two transformers (with space for two more), and a bus coupler.132 kV
switchgear, in double bus bar arrangement, for two transformers (with space for two more),
one bus coupler, and four transmission circuits (with space for four more). The Biyagama
31
site has been selected as the closest possible one to Colombo allowing access for lines into
all existing or planned major substations in and around the city. It is close to the
Sapugaskande substation and free trade zone for heavy industry.
Figure 2.20:Biyagama Grid Sub Station
220kV, 70.5km long, double circuit line from Kothmale power station to Biyagama
switching station was energized in 1984 to dispatch hydro power generated at the Mahaweli
complex power stations namely Kothmale, Victoria, Rantembe and Randenigala. The
maximum power generated at Mahaweli complex is nearly 660MW. Due to the
environmental factors maximum generation is possible only during raining (wet) season.
ACSR type duplex Zebra (400sqmm) is used as a conductor of the Kotmale Biyagama line.
This overhead line consists of two circuits mounted on steel lattice towers. The circuit is
designed for a maximum 700 C conductor temperature. The thermal rating at night time and
day time is 1450 A and 1960A respectively. Two series of distance protection schemes
(Permissive under reach transfer tripping) consisting of two types of distance relays from
two different manufactures were used to protect the line. Single phase auto reclosing facility
and breaker failure protection is incorporated. Distance relays, CT windings and circuit
breaker trip coils are duplicated to improve reliability of operation. Two power line carrier
channels are used to transmit the trip signal between relays located at both ends. To provide
maximum lightning protection two earth wires are mounted with zero shielding angles. Trip
coils are duplicated to improve reliability of operation. Two power line carrier channels are
used to transmit the trip signal between relays located at both ends. To provide maximum
lightning protection two earth.
32
Biyagama to Kelanitissa 220 kV transmission line is 16 km long, double circuit, having
two 300 sq. mm ACSR conductors per phase. Kelanitissa and Kolonnawa substations
together supply the central part of the city of Colombo, where very rapid load growth is
expected. Biyagama to Pannipitiya 220 kV transmission line is a double circuit line 17 km
long, having one 400 sq. mm ACSR conductor
per phase. It was built for 220 kV but
operated initially at 132 kV.
2.2.4 Component of A Grid Sub Station
Biyagama substation is an assembly of the following major electrical equipment:

Electrical Power transformers

Bus bars

Instrument transformers

Lightning arresters

Conductors& Insulators

Circuit breakers

Isolators

Relays
2.2.5 Electrical Power Transformer
The power transformer is the most expensive equipment in a transmission grid substation
and it does not require any exaggeration to understand the importance of operating and
maintaining it properly for a longer service and for a reliable power supply.
Figure 2.21: Main Transformer Of Biyagama Sub Station
If we consider about transformer of Biyagama substation these power transformers were
installed with the introduction of Mahaweli Hydroelectric project; hence the transformers
are more than 30 years old now. Power transformers equipped with on-load tap changers
(OLTCs) have been the main components of electrical networks. OLTCs enable voltage
33
regulation and/or phase shifting by varying the transformer ratio under load without
interruption. Name and specifications of transformers are shown in below table.
Table 2.10: Specifications Of Transformers Of Biyagama
Name
250/3MVA transformer
Outdoor use oil immersed air cooling non
pressure sealed type.
on-load tap-changing transformer
HV
200/3-250/3 MVA
Rated power
I.
MV
200/3-250/3 MVA
LV
60/3MVA
Rated frequency
50Hz
Phase
Single
Name of sub station
Biyagama
Rated Voltage
HV
220√3kV
MV
132√3kV
LV
33Kv
Total weight
81000Kg
Total oil amount
23050Liter
Type of cooling
ONAN/ONAF
Standard
IEC
Number of Tap
13
Manufacture
Takaoka Co.Ltd., Japan
Temperature rise
Win d
55°C
Oil
50°C
Maintenances and Checks of Transformer
In the daily maintenance and check the operating condition of various units may be check in
the walk –round check of the equipment in the plant yard.

Transformer Temperature
Transformer temperature has direct effect on the life of the insulation and it is so constructed
as to prevent oil temperature from exceeding either 90°C for an open from or 95°C for sealed
type when ambient temperature is 40°C.
34

The Amount of Oil
The amount of insulation oil has great effect on the insulating and cooling functions. so,
check as often as required to confirm the appropriate oil level. Also, quality of following
components are checked in maintenance.
i.
ii.
iii.
iv.
v.
vi.
Protective relays
Oil feed pump
On load tap changer
Non –voltage tap changer
Bushing
Protective relay.
2.2.6 Circuit Breaker
The circuit breakers are used to break the circuit if any fault occurs in any of the instrument.
These circuit breaker breaks for a fault which can damage other instrument in the station.
For any unwanted fault over the station we need to break the line current. This is only done
automatically by the circuit breaker.
These are load switches. It is able to make or break the normal load current as well as the
fault currents. The basic construction of any circuit breaker requires the separation of
contacts in an insulating fluid, which serves two functions. It extinguishes the arc drawn
between contacts when the CB opens and it provides adequate insulation between the
contacts and from each contact to earth. For successful operation of the circuit breaker, two
functions are to be performed. These are Operating mechanism function and Arc quenching
function. There are various operating mechanisms such as spring charge mechanism,
Pneumatic mechanism and Hydraulic Mechanism. Minimum oil (called minimum oil circuit
breakers-MOCB) and SF6 gas (called Sulphur Hexafluoride-SF6 gas CB) are used as arc
quenching medium for CB in Biyagma substation.
I.
Minimum Oil Circuit Breaker
Minimum oil circuit breaker consists of two oil filled chambers namely upper chamber and
lower chamber which are separated from each other. There is extinction process is carried
out in upper chamber. So, it is called an are extinction chamber or current interruption
chamber of minimum oil circuit breakers(MOCB). This chamber house and are control
device, an upper fixed contact and ring shaped lower fixed contact. There is control device
is fitted to the upper fixed contact. The moving contact slide through the lower fixed contact
such that a physical (or electrical) maintained between them. The electric assembly of upper
35
fixed contact, lower fixed contact and arc control devices enclosed in a glass fiber enclosure
which is surrounding oil. The oil present in the lower chamber does not involve the arc
extinction process and instead it is used only for insulation purpose. The operating rod which
is permanently fixed to the moving contact is connected to the operating mechanism which
provide vertical motion in order to make and break the circuit.
Figure 2.22:Minimum Oil Circuit Breaker Re- Installation
II.
SF6 Circuit Breakers
Sulphur hexafluoride (SF6) is an inert, heavy gas having good dielectric and arc
extinguishing properties. The dielectric strength of the gas increases with pressure and is
more than the dielectric strength of oil at 3 kg/cm2. The use of SF6 circuit breaker is mainly
in the substations which are having high input KV, say above 220KV and more. The gas is
put inside the circuit breaker by force i.e. under high pressure. When if the gas gets decreases
there is a motor connected to the circuit breaker. The motor starts operating if the gas went
lower than 20.8 bar. There is a meter connected to the breaker so that it can be manually
seen if the gas goes low. The circuit breaker uses the SF6 gas to reduce the torque produce
in it due to any fault in the line. The circuit breaker has a direct link with the instruments in
the station, when any fault occurs alarm bell rings.
36
2.2.7 Isolator and Earth Switches
Isolators are the no load switches and used to isolate the equipment. (Either line equipment,
power transformer equipment or power transformer). With the isolators, we are able to see
the isolation of the equipment with our naked eye. The line isolators are used to isolate the
high voltage from flow through the line into the bus. This isolator prevents the instruments
to get damaged. It also allows the only needed voltage and rest is earthed by itself.
Isolator is a type of switching device. It has no control devices. Isolator is operated after the
circuit breaker is opened. While closing the circuit, first close the isolator and after the circuit
breaker is closed. Strictly speaking Isolators are operated under no current condition. In the
following cases it is permissible to use isolator for making and breaking of the circuits. Air
break isolators or disconnecting switches are not intended to break load though these are
meant for transfer of load from one bus to another and also to isolate equipment for
maintenance. These are available mainly in two types vertical break type and horizontal
break type. The later type requires larger width. However, the space requirement can be
reduced in the horizontal break isolators by having double break with a center rotating pillar.
Pantograph and semi-pantograph disconnects involve vertical movements of contact arm and
therefore require less separation between phases and thereby require less separation between
phases and thereby help in reducing the sub-station area to a larger extent. The isolators
could be operated mechanically or hydraulically or pneumatically or by electric motor.
Earthling facility shall be provided wherever required.
37
Figure 2.23:Isolaters In 220Kv Switch Yard
2.2.8 Current Transformers
Current transformer is a current measuring device used to measure the currents in high
voltage lines directly by stepping down the currents to measurable values by means of
electromagnetic circuit.
Figure 2.24: Current Transformers
2.2.9 Potential Transformers
An instrument transformer in which the secondary voltage, in normal conditions of use, is
substantially proportional to the primary voltage and differs in phase from it by an angle
which is approximately zero for an appropriate direction of the connections.
Basic Functions of Voltage Transformers are:
38

To reduce the line voltage to a value which is suitable for standard measuring
instruments relays etc.

To isolate the measuring instruments, meters, relays etc. from high voltage side an
installation.

To sense abnormalities in voltage and give signals to protective relays to isolate
the defective system.
2.2.10 Bus Bar
Bus bars are the part of the substation where all the power is concentrated from the incoming
feeders, and distributed to the outgoing feeders. That means that the reliability of Biyagama
substation depends on the reliability of the bus bars present in the power system. An outage
of any bus bar in Biyagama substation can have dramatic effect on Sri Lankan Power system.
An outage of a bus bar leads to outage of the transmission lines connected to it. As a result,
the power flow shifts to the surviving healthy lines that are now carrying more power than
they are capable of. This leads to tripping of these lines, and cascading effect goes on until
there is blackout or similar situation.
I.
Bus bar scheme of Biyagama substation
Bus bar scheme of Biyagama substation is double bus bar scheme (2BB). the more complex
scheme of a double bus bar system gives much more flexibility and reliability during
operation of the substation. For this reason, this scheme is used for distribution and
transformer substation nodes of the power supply system. It is possible to control the power
flow by using the bus bars independently, and by switching a feeder from one bus bar to the
other. Because the bus bar
disconnections are not able to break the rated current of the
feeder, there will be a short disruption in power flow.
39
Figure 2.25:Diagram Of 220 kV Transformer Bay Section
2.2.11 Grid Substation Overloading and blackout
Overloading of grid substations is defined based on the loading levels of grid substation
power transformers. Overloading of transformers must be avoided to avoid overheating,
leading to equipment damages and reducing the life time.
The total system failure on 13 March 2016 has initiated with the failure of tap changer of
one of the 220/132/33kv transformers in Biyagama Grid substation which has activated the
bus bar protection making the Grid dead. The subsequent collapse of Norochcholai coal
power plants triggered the system failure. The complete system restoration was taken almost
seven hours and hence the impact was immense.
2.2.12 Introduction to System Control Center
The system control center is the central nerve system of the power system. It senses the pulse
of the power system adjusts its condition and coordinates its movement. Normally, system
control center collects real-time data of MW power outputs from power plants to conduct
frequency control (FC) and economic dispatch (ED).
Using system frequency as a surrogate measurement of power balance between generation
and load in the country, frequency control was used to control generation in order to maintain
frequency. A power generating system has the responsibility to ensure that adequate power
is delivered to the load, both reliably and economically. The quality of power supply is
affected due to continuous and random changes in load during the operation of the power
system. Hence, the system control center is required to maintain a continuous balance
between power generation and load demand.
According to the Power system regulations and practice of Sri Lanka, it has been identified
that:
40

Voltages at the live bus-bars of CEB network:
220 kV ±5%
132 kV ±10%

System frequency (SF):
Normal operating range: 50 Hz ±1%
According to the current practice of CEB,
Normal operating range: 50 Hz ±4%
Short term variations: -6% to +5% up to 3s.
2.2.13 Present Situation of Frequency Control in Sri Lanka
At present, 10 water turbines at 4 hydro power stations, Victoria (70MW×3, reservoir pond
type), New Laxapana (50MW× 2, regulating pond type), Samanalawewa (60MW× 2,
reservoir pond type) and Kotmale (67MW×3, reservoir pond type), are used for frequency
control. Both Victoria and New Laxapana are used mainly for frequency control, and
Samanalawewa and Kotmale are used subordinately. New Laxapana is used about 1500
hours per year, and Samanalawewa is used about 5 hours per month. 10 water turbines of 4
hydro power stations can be used for frequency control, but only one water turbine can be
used at one time for frequency control except at Samanalawewa. Two or three water turbines
cannot absorb load changes together at the same time. Only two units of Samanalawewa can
absorb load changes together at the same time. Of course, some water turbines at different
power stations cannot absorb load changes together at the same time.
In Sri Lanka, governor free operation is used as a frequency control system. Under this
control system, an amount of control offset (frequency deviation) is allowed, and control
offset is manually cancelled by changing the output of water turbines.
2.2.14 Frequency Controlling Method Use in Sri Lanka
Turbine power in accordance with the pre-determine power in accordance with Generating
stations identified by the System Control Centre (SCC) of Ceylon Electricity Board (CEB)
situated at Kotmale, Victoria, Laxapana and Samanalawewa which perform manual
secondary frequency control. The SCC decides and selects one of these four generating
stations to control the system frequency at a given time. The decision of the SCC is
dependent on many aspects such as the available water storage capacity, downstream
irrigation requirements and transmission line constraints. While the system is on steady state,
when a sudden load is added to the power system, stored kinetic energy of turbine generators
initially contributes in real time to help avoid the sudden imbalance between generation and
41
demand. As a result, turbine generator speeds drop. Following the change in turbine speeds,
and hence the frequency, governors intervene and adjust the pre-determined set value, based
on governor droop characteristics.
2.2.15 Droop Characteristics of a Generator
In Sri Lanka, one of the four frequency controlling stations controls the system frequency at
a time, while other stations are operated on a fixed output as determined by the SCC. The
“master” frequency controlling station selected for this study is the 67MW unit of Kotmale.
Speed droop characteristics of Kotmale hydro power plant are shown in Figure 2.26
Figure 2.26: Speed Droop Characteristics Of Kotmale Hydro Power Plant
When on frequency control, the power plant generally operates closer to the midpoint of its
Unit capacity range of 0 to 67MW. When the demand increases or decreases and when the
frequency decreases or increases as a result, the operating point is moved first along the
normal droop characteristic curve (marked 1) and settles down at a point above or below the
set point corresponding to 50Hz. When the steady state operating point moves along the
droop characteristic curve (without a change in the speed reference), the wicket gate position
is adjusted by the governor controller via hydraulic actuators which adjust the active power
delivered by the generator.
42
After Kotmale and all other generators connected to the system have changed their outputs
to match the change in the demand, the frequency would settle down at a new steady state
value along curve “1”, which is different to 50Hz. At that point, operators at the station on
frequency control which is Kotmale in this case, adjust the “speed reference”, or shift the
droop characteristic curve in Figure 2.26 to another parallel line (either 2 or 3), until the
frequency is brought back to 50Hz. Once the frequency is brought back to 50Hz by Kotmale
operator, all other stations that were on fixed load, would once again adjust their outputs to
the points in the droop characteristic curve corresponding to the fixed outputs as requested
by the SCC prior to the disturbance.
2.2.16 Basic Principles of Power System Operation
Basic principles of system operation in the CEB power system are as follows:
Reservoir pond type power stations, like Victoria, and Gas Turbine units are power sources
for peak demand, but not for base demand. These power stations should be mainly operated
at night peak and semi-peak, but not during the off peak portion of the night. Power stations
which are obliged to run even during the off peak portion of the night, like New Laxapana,
should be mainly used for frequency control during the mid-night period, midnight to 6 a.m.,
instead of reservoir pond type power stations, like Victoria.
At the end of the rainy season, all of the water levels at reservoir ponds should reach their
highest levels and water levels should be kept as high as possible (High Water Level
Operation).
When large scale units, such as the 300MW units, stop due to sudden outage or scheduled
maintenance, gas turbines should be operated as little as possible. Reservoir pond type power
plants should be mainly operated instead of the large scale unit. After the large scale unit is
operated in parallel, water levels at each reservoir pond should be restored to the scheduled
level.
When an amount of water is given, it is most efficient to share the discharge equally among
the water turbines running parallel. Hence, when frequency control operation is required, it
is desirable to absorb load changes equally among water turbines running in parallel. (High
Efficiency Operation due to Governor Joint Operation)
Since, in the Kelani Complex, all three regulating ponds, Laxapana, Canyon and Norton
regulating ponds, have only a small capacity, it is very hard to change output freely and
suddenly. Sudden and big load changes, such as large scale units dropping out or load
forecast error, should be absorbed by power stations with their reservoir pond type power
stations with less restrictive conditions, like Victoria and Samanalawewa. In addition,
43
Polpitiya has oscillation problems. In this case, output per unit running at Polpitiya should
be fixed at 35MW or more, and total output at Polpitiya should be decided by the number of
units in service. Total output at Polpitiya should be either 0MW, about 35MW or about
70MW. (High Efficiency Operation due to Starting and Stopping)
Next Day Operation Plans should be decided on the condition that:
Polpitiya is operated at a fixed load, about 35MW per unit and Next day, all power stations
with small regulating ponds in the Kelani Complex are operated on a schedule decided the
previous day. Load forecast error and outage at other plants should be absorbed mainly by
Victoria and Samanalawewa with less restrictive conditions. The number of startup and shut
off events may increase at most once or twice per day more than now, and hardly effect
machine life.
Water turbines at the power stations with reservoir ponds or regulating ponds should not be
operated at light load except for unavoidable reasons, such as frequency control and
irrigation demand. By using the regulating capacity of the regulating ponds or reservoir
ponds fully, starting and stopping of water turbines should be done moderately and always
operated near maximum efficiency output. Since excessive saving of investment and
maintenance expenditure causes fuel expenditure increase, reasonable and moderate
judgement is indispensable.
2.2.17 Black Out Situation in Sri Lanka
Power system of Sri Lanka has a daily maximum power consumption of around 2, 100 MW.
This always falls as the night peak of the ‘Load Curve’ of Sri Lanka. A 65% of the total
generation is from thermal and the majority of the balance is from Hydro Power Plants (PP).
Currently, around 200 MW of the total generation is from embedded generation, which
comprises with Hydro and wind power. 900 MW ‘Lakwijaya’ PP (which is the PP with
highest capacity in Sri Lanka and has been connected to the grid in 2011), contributes the
system with approximately as, 22% of the total installed capacity, while 26% of the average
generation. Since it operates on coal, cost of a unit of electricity is considerably low
compared to that of all other thermal plants. Therefore, it performs a very important role in
economic aspects too. Hence, if it happened to isolate “Lakwijaya” from the national grid
due to a faulty situation, there would be a considerable impact on the PS stability that may
lead to a system brown-out or black out situation. On the other hand, with the increased
penetration of intermittent renewable energy, PS encounters increased uncertainty and
variability causing generation and load imbalances.
44
2.2.18 Under-Frequency Load Shedding
During a Load and Generation imbalance situation, since the amount of over load is not
known at the instant of disturbance, the load is shed in blocks until the frequency stabilizes.
Different methodologies are available for implementing Load Shedding schemes the three
main categories of Load Shedding methodologies are traditional, semi-adaptive and
adaptive.
Traditional Load shedding scheme is mostly implemented because of its fewer requirements
of sophisticated relays. It sheds a certain amount of load when the system frequency falls
below a threshold. If this load drop is sufficient, the frequency will stabilize or increase. This
process continues until the frequency sensitive relays get operated. The value of the
threshold and the relative amount of load to be shed are decided off line based on experience
and simulation. Although this approach is effective in preventing inadvertent Load Shedding
in response to small disturbances with relatively longer time delay and lower frequency
threshold, it is not able to distinguish between normal oscillations and large disturbances of
the power system. Thus, this approach is prone to shed lesser loads at large disturbances.
The semi adaptive Load Shedding scheme uses the frequency decline rate as a measure of
the generation shortage. In this scheme, the rate of change of frequency thresholds and the
size of load blocks to be shed at different thresholds are decided off-line on the basis of
simulation and experience.
Adaptive Load Shedding scheme is the one that can prevent black-outs through controlled
disintegration of a power system into a number of islands together with generation tripping
and or Load Shedding. Table 2.11 gives the Load Shedding scheme that is being
implemented in Sri Lanka.
Table 2.11 :Load Shedding Scheme In Sri Lanka
Frequency
Time Delay And Magnitude Of Load Shedding
f ≥48.75 Hz
State
f < 48.75 Hz
f < 48.5 Hz
f < 48.25 Hz
No load shed
Step 1: 6.5% of load 100 ms time delay
Step 2: 6.5% of load 500 ms time delay
Step 3: 12% of load 500 ms time delay
f < 48 Hz
Step 4: 9%+3.5%* =12.5% of load 500 ms time delay
f < 47.5 Hz
Step 5: 3%+4.5%* =7.5% of load Instantaneous
f < 49.0 Hz and -0.85<df/dt
13%+3.5%+4.5%=21% of load, 100 ms time delay
45
2.2.19 Operational Planning and Dispatch
The use of individual generators is driven by operational planning and dispatch decisions.
The objective of these decisions should be to minimize the total costs of electricity supply
while complying with the practical constraints imposed by different technologies and by the
electricity transmission system. In this section, I review the current operational planning and
dispatch of system control center.
2.2.20 Utilization of Hydro Generation
Hydro output is driven by hydrological conditions. The best measure of operating efficiency
of hydro power plants is, therefore, the extent to which water storage is managed effectively
to ensure adequate resources are available to meet peak demand and displace costly thermal
generation.
Reservoirs in Sri Lanka fill during the South West monsoon from May to September. The
optimal water management policy, as regards electricity generation, is, therefore, to reduce
reservoir levels to their lowest point by the start of May before allowing them to refill up to
September. The stored water can then be used during the period to the start of the North East
monsoon, in December to February, which again replenishes reservoirs.
External constraints on the management of water storage and releases must be considered.
In planning water storage and release from the Mahaweli complex, priority is given to
meeting irrigation requirements under ‘dry’ year conditions. Once the resulting water release
requirements have been calculated, the expected generation from hydro power plants is
determined. If, after allowing for projected thermal generation, there remains a shortfall
relative to expected demand then planned output from hydro plants is increased and water
release programmes adjusted accordingly. The final programme of projected releases and
generation is provided to CEB for its operational planning.
2.2.21 Software and Methodologies of System Control Center
Operational data is very important for system operations. However, SCC is not equipped
fully with a Supervisory Control and Data Acquisition/Energy Management System
(SCADA/EMS), which can be used to collect data automatically. A SCADA system was
installed in 1990 and upgraded in 2008 but does not have full coverage of the electricity
system. Instead most operational data is still collected manually.
46
I.
Software
SCC uses the following software packages:

Long-term and medium-term generation operation planning: SDDP

Day-ahead and three day-ahead generation operation planning: NCP

Power system study: PSS/E
These are all standard software packages used extensively by other system operators
internationally. However, there are some limitations. In particular:
SDDP and NCP are designed as longer-term operational planning tools. To reduce
computational time, SDDP does not use hourly modeling meaning it cannot readily represent
the constraints on hour-by-hour dispatch. The two models are also unable to represent
individual power plants in detail. This reduces their accuracy and increases the level of
forecasting errors.
SCC has explained that the SDDP and NCP software was recently procured to comply with
the requirements of the Methodology for Merit Order Dispatch issued by PUCSL. This
software is used to prepare longer-term operational plans for the purposes of reservoir
management, maintenance scheduling, and fuel procurement.
II.
Planning
At present, SCC’s planning horizons are as follows: year-ahead, six month-ahead, monthahead and day-ahead. The year-ahead plan is repeated every month, and has a planning
horizon of 12 months into the future, the first month result is month-ahead operation
planning. The daily plan is taken rolling for the next three days
III.
Real-Time Dispatch
Real-time dispatch uses the most recent day-ahead plan. Deviations from this only occur
where a generator fails or actual load deviates very substantially from forecast levels. In
these instances, SCC revises the plan by rerunning the calculation in NCP. In emergency
situations, load is shed according to a pre-determined plan
IV.
Methodologies
At each step of the planning process, SCC prepares forecasts of system load, water inflows
to hydro power plants (and, therefore, hydro generation) and renewable energy output. It
then imposes physical constraints on the operation of thermal power plants (eg, start and
stop timings) and on the transmission system and inputs the variable or energy costs of
generators and requirements to hold-back a part of capacity to provide spinning reserve.
47
Planning software is then used to calculate the resulting optimal operational plan under a
number of scenarios.
The issues identified in the methodologies applied relate to load forecasting, the forecasting
of water inflows, the setting of spinning reserve levels and the selection of scenarios for
modeling.
V.
Power Transmission Line Control Procedure
In general transmission system analysis comprise load flow studies, reliability studies and
stability studies. To identify controlling criteria violation and required mitigating measure
these studies are required. Load flow studies are required to determine the power system
performance in steady state.

Voltage criteria
The voltage criterion defines the permitted voltage deviation at any live bus bar of the
network under normal operating condition as given table 2.12
Table 2.12:Voltage Criteria
Bus bar voltage
Allowable voltage variation
220Kv
±5%
132Kv
±10%
2.2.22 Introduction to Transmission and Generation Planning in Sri Lanka
The Ceylon Electricity Board (CEB) is under a statutory duty to develop and maintain an
efficient， coordinated and economical system of Electricity Supply for the whole of Sri
Lanka. Therefore, CEB is required to generate or acquire sufficient amount of electricity to
satisfy the demand. In order to fulfill the requirement, CEB annually plans its development
activities in the document as Long Term Generation Expansion Plan covering the growing
electric power demand. The analysis was done based on the study processes and results of
Long Term Generation Expansion Plan (LTGEP), which was prepared by the Generation
Planning Section, Transmission and Generation Planning Branch, Ceylon Electricity Board.
The following scenarios were chosen to analyze in the study to compare the adherence of
the above energy policy elements:

Scenario 1: Baseline Scenario – Scenario which fulfill the forecast future electricity
demand under least cost principle while absorbing optimum Non-Conventional
Renewable Energy (NCRE) to the system by year 2020
48

Scenario 2: Reference Scenario– Scenario considering no future NCRE
developments

Scenario 3: Energy Mix Scenario – Scenario considering fuel diversification in to
LNG and Nuclear

Scenario 4: Demand Side Management (DSM) Scenario – Scenario considering
Demand Side Management forecast by Sustainable Energy Authority (SEA)

Scenario 5: Scenario with Natural Gas - Considering Recoverable Natural Gas
potential in Mannar Basin by 2020
2.2.23 Electricity Demand Forecast Method and Past Demand
I.
Past Demand
Figure 2.27 shows the country’s daily load curve recorded on the day of annual peak for
previous eight years. From the Figure 2.27, it is seen that the shape of the load curve has not
changed much during the last eight years. The system peak demand occurred only for a short
period from about 19.00 to 22.00 hours daily. The recorded maximum system peak is
2,164MW in year 2013, while in year 2014 the peak is 2,152MW.
Figure 2.27:Daily Load Curve
Electricity sales are forecasted using econometrical analysis. The model for the analysis is
carefully composed based on the national policy of each category. Power generation at
sending end is projected based on the electricity sales forecast, considering the
49
transmission/distribution losses, renewable energy forecasting, and the effect of energy
conservation measures /DSM prediction.
II.
Methodology
Econometric approach which combines economic theory and statistical techniques is used
to estimate the relationship between electricity demand and GDP, electricity prices,
population, energy intensity, household electrified, and number of rural electrification
schemes completed. The electricity demand is chosen as the explained variable and other
remaining variables are chosen as explanatory variables. Using historical data from 1977 to
2013 pertaining to the above seven variables, this relationship is derived by employing the
special technique e. However, prior to fitting the model, time series properties of data and
the order of integration need to be investigated for stationary.
The electricity demand considered in this study is the total consumption of electricity (in
GWh) in Sri Lanka. This represents the total amount of electricity consumed by all electricity
consumers which include domestic, commercial and industrial customers. This regression
analysis will be performed against different sectors like, domestic, industrial and others as
there are different consuming habits within these categories.as an example following
analysis method use for forecast domestic sector demand. In regression analysis, it was found
that two variables for domestic sector: Gross Domestic Product Per Capita and Previous
Year Domestic Consumer Accounts were significant independent variables for the domestic
sector demand growth.
Ddom (t) i = 84.602 + 6.017 GDPPC (t) i + 0.661 CAdom (t − 1)
Where,
Ddom (t) - Electricity demand in domestic consumer category (GWh)
GDPPC (t) - Gross Domestic Product Per Capita (’000s LKR)
CAdom (t-1) - Domestic Consumer Accounts in previous year (in ’000s)
2.2.24 Long Term Transmission Plan
Based on these 10-year regional demand forecasts, and the annually updated generation
expansion plan, the CEB’s Transmission Planning Branch prepares a 10-year transmission
expansion plan. This plan is updated every year. This plan is prepared at a national level and
is a comprehensive plan, using tools such as Power System Simulation Software (PSS/e),
and provides information with regard to security analysis, stability, fault levels and reliability
of the system. The plan also provides information on the weak points in the system and
50
proposes new projects to accommodate the new generation additions as well as to improve
the quality and reliability of supply to customers.
The main issues considered for transmission development are:
i.
Transmission lines and inter-bus transformer overloading under normal and single
outage (n-1) operating conditions
ii.
Overloading of transmission equipment under normal and single outage (n-1)
operating conditions
iii.
Corrective measures for voltage criteria violations under normal and single outage
(n-1) operating conditions
iv.
Corrective measures for transient stability criteria violations
2.2.25 Introduction to Heavy Maintenance of Low Voltage Transmission Line
The main supporting unit of overhead transmission line is transmission tower. Transmission
towers have to carry the heavy transmission conductor at a sufficient safe height from
ground. In addition to that all towers have to sustain all kinds of natural calamities.
Figure 2.28 :33kv Transmission Tower
So transmission tower designing is an important engineering job where all three basic
engineering concepts, civil, mechanical and electrical engineering concepts are equally
applicable. A power transmission tower consists of the following parts,

Peak of transmission tower

Cross arm of transmission tower

Boom of transmission tower
51

Cage of transmission tower

Transmission Tower Body

Leg of transmission tower

Stub/Anchor Bolt and Base plate assembly of transmission tower.
The main parts among these are shown in the figure.
I.
Peak of Transmission Tower
The portion above the top cross arm is called peak of transmission tower. Generally, earth
shield wire connected to the tip of this peak.
II.
Cross Arm of Transmission Tower
Cross arms of transmission tower hold the transmission conductor. The dimension of cross
arm depends on the level of transmission voltage, configuration and minimum forming angle
for stress distribution.
III.
Cage of Transmission Tower
The portion between tower body and peak is known as cage of transmission tower. This
portion of the tower holds the cross arms.
IV.
Transmission Tower Body
The portion from bottom cross arms up to the ground level is called transmission tower body.
This portion of the tower plays a vital role for maintaining required ground clearance of the
bottom conductor of the transmission line.
Figure 2.29:Part Of Transmission Tower
2.2.26 Design of Transmission Tower
During design of transmission tower the following points to be considered in mind,
52

The minimum ground clearance of the lowest conductor point above the ground
level.

The length of the insulator string.

The minimum clearance to be maintained between conductors and between
conductor and tower.

The location of ground wire with respect to outer most conductors.

The mid span clearance required from considerations of the dynamic behavior of
conductor and lightening protection of the line.
Figure 2.30:Transmission Tower Construction In Badulla Area
2.2.27 Types of Transmission Tower
According to different considerations, there are different types of transmission towers. The
transmission line goes as per available corridors. Due to unavailability of shortest distance
straight corridor transmission line has to deviate from its straight way when obstruction
comes. In total length of a long transmission line there may be several deviation points.
According to the angle of deviation there are four types of transmission tower.
I. A – type tower – angle of deviation 0o to 2o.
II. B – type tower – angle of deviation 2o to 15o.
III. C – type tower – angle of deviation 15o to 30o.
IV. D – type tower – angle of deviation 30o to 60o.
As per the force applied by the conductor on the cross arms, the transmission towers can be
categorized in another way. Tangent suspension tower and it is generally A - type tower.
53
Angle tower or tension tower or sometime it is called section tower. All B, C and D types of
transmission towers come under this category. Based on numbers of circuits carried by a
transmission tower, it can be classified as;
I.
Single circuit tower
II.
Double circuit tower
III.
Multi circuit tower.
2.2.28 Transmission Line Maintenance
By using live line techniques to maintain transmission line infrastructure, circuits and
transmission lines are able to remain in service while maintenance tasks are carried out. This
is a major advantage to transmission asset owners because less redundancy is needed in the
transmission network. Electricity consumers who are supplied by spur lines (single circuit
supplies typically in rural areas) also benefit from live line work. They do not suffer the
inconvenience of a cut in their electricity supply every time maintenance is carried out on
their supply lines. Given the high cost of transmission lines and the impact that transmission
lines have on the environment, there is a major advantage in being able to avoid duplication
of assets purely for maintenance purposes.
Figure 2.31:Hot Line Maintenance In Transmission Line
54
Live Line Maintenance can be Resorted for
•
Changing of insulators
•
Replacement of damaged section of conductor
•
Testing of insulators (on-line insulator tester)
•
Changing of cross arm
•
Changing of poles
•
Transferring conductor to higher pole
2.2.29 Major Tools Used for Live Line Maintenance

Wire tongs: Normally used on pin type or suspension type construction for
maneuvering and holding live conductors clear of the working area or for transferring
to conductors to knee positions.

Wire tongs saddle: are used to secure wire tongs to a structure.

Tie stick: used for manipulation of the wires.

Strain link sticks: used principally for supporting heavy conductor loads either for
assisting wire tongs or for supporting entire load when changing insulators on
running corners and dead end structures.

Roller link sticks: used principally to hold conductors aside when relocating poles in
mid span.

Suspension link sticks: principally designed for lifting the conductor to relieve the
strain from suspension insulators on high voltage lines.

Strain carrier: used principally for relieving the strain on conductors when changing
insulators on dead end structure.

Auxiliary arms: used principally for holding conductors while damaged conductors
or cross arms are being changed on pole structure.

Double string dead end insulator tool: normally used to remove the strain from the
one side of the double insulator strings.

Gin poles: Used for lifting heavy conductors, hoisting transformers switches and
other heavy items around energized conductors and other objects.

Cum-a-along-clamp: normally used to grip the conductor when tension is applied to
the clamps by rope blocks, link sticks etc.

Safety equipment like conductor guards, cross arm guards, insulator covers, hand
gloves etc.
55
Techniques used are Hot line maintenance is usually done by using one of the following
methods:
I.
Hot Stick Method Using Insulated Sticks
In this method the linemen are at the ground potential and is isolated from the energized
conductor. This method is generally adopted for transmission lines up to 220 KV. The sticks
enable the linemen to carry out the work without infringing minimum clearance distances
from live equipment. Tools, such as hooks or socket wrenches can be mounted at the end of
the pole. More sophisticated poles can accept pneumatically or hydraulically driven power
tools which allow, for example bolts to be unscrewed remotely. A rotary wire brush allows
a terminal to be scoured clean before a connection is made. However, a worker's dexterity is
naturally reduced when operating tools at the end of a pole that is several meters long.
Figure 2.32:Hot Stick Use In Hot Line Maintenance
II.
Bare Hand Technique
In this method linemen works either from the insulated bucket / truck or ladder and is bonded
to the energized conductor and isolated from the ground. This method is generally employed
for transmission lines above 220 kV. However, this method is not use by CEB –DD3.
III.

Major Safety Precautions to be Observed During Live Line Working.
A golden rule for hot line operation is "nothing is too safe when a life is at stake".
Records prove that hot line work on high voltage lines is actually safer than
maintenance work on "Cold" lines which could possibly become energized while the
line is being worked. Linemen working with hot sticks are always conscious of the
56
danger involved, and being aware of this danger they work more cautiously and keep
a safe distance

While working it should be kept in mind that the person working invariably keeps a
certain distance from the earth point. In addition to this he should also keep a certain
safe distance from the other phases of the lines.

Use freely safety equipment like cross-arm guards, hand gloves, etc.

Never use a tool which is not tested and which is not familiar, never use a damp tool.

Do not exceed the manufacturer’s ratings in the use of hot line tools. Linemen must
know the approximate weight of a conductor span and the line tensions which they
are dealing with. When in doubt use a longer tool or two identical tools.

Check each tool regularly for indicating that the tool may have been overstressed.

When not in use, tools should be kept in the tool container and not on the ground.
IV.
Cold line maintenance
In the cold line method, the maintenance is carried out by availing outage on the line. The
works of replacement of defective insulator string. tightening loss nuts and bolts, cold line
insulator washing and defects noticed in through line patrolling are rectified, however since
there is interruption in the line, there is huge revenue loss and customer dissatisfactions
which are the main disadvantage in cold line maintenance.
2.3
Distribution Division
2.3.1 Introduction to Distribution Division
Ceylon Electricity Board (CEB) is the licensee which is responsible for generating,
transmitting, distribution and sale of electrical energy in majority the geography of Sri
Lanka. While being the sole licensee for transmission it is also the licensee for bulk of the
power generation in the country. Further, through four licenses for distribution and sale of
electricity, it covers the entire geography of the country including the perimeter sea up to the
border.
The Distribution System of the Ceylon Electricity Board (CEB) is divided in to four
distribution divisions. Each Distribution Division is managed by an Additional General
Manager. A Distribution Division comprises of several Distribution Provinces and
Distribution Areas, but the boundaries of these Distribution Provinces may not necessarily
coincide with the boundaries of administrative provinces of Sri Lanka. A Distribution
Province is managed by a Deputy General Manager while an Area is managed by either a
57
Chief Electrical Engineer or an Electrical Engineer, generally referred to as the Area
Electrical Engineer.
The Distribution Division 4 covers a part of the Western Province (Western Province South
I), the entire Southern Province and a few parts of the Sabaragamuwa and Uva Provinces.
Western Province South I covers the Areas of Ratmalana, Kalutara and Dehiwala and
Southern Province covers the Areas of Ambalangoda, Galle, Hambantota, Matara, Tangalle,
Weligama and Baddegama. The Distribution network of Division 4 extends from Dehiwala
to Kataragama.
2.3.2 Transmission Lines of Distribution Network
Power Transmission Lines The most common methods for transfer of electric power are
Overhead AC and Underground AC. An overhead power line is a structure used in electric
power transmission and distribution to transmit electrical energy along some distances. It
consists of one or more conductors (commonly multiples of three) suspended by towers or
poles. Since most of the insulation is provided by air, overhead power lines are generally the
lowest-cost method of power transmission for large quantities of electric energy.
Towers for support of the lines are made of wood, steel (either lattice structures or tubular
poles), and concreate poles. The bare wire conductors on the line are generally made of
aluminum A major goal of overhead power line design is to maintain adequate clearance
between energized conductors and the ground so as to prevent dangerous contact with the
line, and to provide reliable support for the conductors.
2.3.3 Present Situation of LV Lines
In Sri Lanka, three-phase four wire system is adopted for LV lines, but many single-phase
two wire systems still remain in rural areas. The conversion from single-phase to three-phase
is being carried out one by one at this moment, thus it may take substantial time to convert
a single-phase line to three-phase line. The losses on LV lines can be reduced to 1/6 times.
CEB’s distribution system uses two kinds of ACSR conductors. One is ACSR Lynx (37/2.79
mm) used for 33 kV trunk lines named the backbone lines and the other is ACSR Raccoon
(7/4.09 mm) used for 33/11 kV branch lines, named the pole lines.
2.3.4 Item Use in Overhead LV Construction
I.
Concrete poles
8.3m or 9m LV reinforced concrete poles shall be under for all new overhead construction
lines higher size of poles may be used in combined run as appropriate
58
Poles position are classified as:

Terminal-where the line is terminated with LV shackle insulators on the pole

Tension –where the line is terminated with LV shackle insulators on both side of the
pole.

Intermediate-where the line is unbroken and supported on LV shackle insulators.
Self-supported poles may be used in urban and densely populated areas where stays and
struts cannot be erected.
II.
Stay assembly
Stay assembly consists of the Stay Rod with Ratchet Nut, Stay Tightener and Stay
Plates
III.
Conductors
Two type of bar conductors are used in low voltage overhead lines these are Fly conductors
(7/3.40mm) ACC and Wash conductors (7/4.39mm) ACC. The aluminum connector and
termination are made out of high strength and high conductivity Aluminum. They are tubular
or H type construction. Four wire Aerial bundled conductor system comprises three
separately insulated aluminum conductors with XLPE (cross link poly Ethylene) aluminum
alloy neutral conductor wire.
IV.
Insulators
The insulator is made of good commercial grade wet process porcelain.it is Brown or White
Glazed and the entire glazed surface is relatively free from imperfection. Three type of
insulators are used in the construction of LV and MV lines they are; Pin, Post and Tension
insulators.

Pin insulators
pin insulators are made of brown glazed porcelain. There pin insulators incorporate a hot
dipped galvanized steel spindle, nuts spring washers two flat washers.
59
Figure 2.33 :Pin Insulator

Line insulators
These solid core line post insulators are made of brown glazed porcelain. these insulators are
incorporate the necessary hardware such as steel spindle, nut, spring washer and 2 Nos. of
flat washers, suitable of fix on channel iron cross arm.

Tension insulators
Tension insulators are disc type and made out of either porcelain or glass. The hardware part
of the disc insulator is cap and pin type assembly with a 16mm ball and socket coupling.
2.3.5 Issues and Concerns to be solved in CEB’s Distribution System

Voltage drop
Voltage drop is observed at many locations on CEB’s distribution system. The root
causes of voltage drop are the distribution of electric power on long distribution lines
and overloading. The following three countermeasures are considered to rectify
voltage drop.


Provide additional distribution lines and/or size up the conductors;

Construct new GS to shorten the distribution lines
Salt contamination along the seaside
Since salt contamination is observed on overhead lines along the seaside, the CEB
60
applied 33 kV insulators for 11 kV distribution lines to increase the creepage distance of
insulators. As a drastic measure to solve salt contamination, cables should be adopted to
distribution lines instead of overhead conductors.
61
Chapter Three
3
3.1
Training Experience –Management
Management Systems of CEB
While the Chairman is responsible through the Board for policy matters and close liaison
with government, the General Manager is CEB's Chief Executive Officer. He is responsible
for the overall direction and control of CEB's day-to-day business. The present General
Manager was recently promoted to the post and is an experienced and long-serving engineer.
He or she is presently assisted by ten Additional General Manager, several Deputy General
Managers and a Finance Manager. With the exception of the Finance Manager, who is fully
qualified in matters of finance, all top management posts are filled by engineers. The
Commercial and Personnel Managers, Chief Internal Auditor, and the Legal Officer all
report directly to the General Manager.
3.2
Asset management
Since asset Management is a part of infrastructure development, this division plays a vital
role in enabling the economic growth, social advancement & environmental development of
the CEB. Assets Management division has branches to handle following work;
3.3
•
Assets Management & Corporate
•
Training
•
Project Management (Vidulakpaya)
•
Workshop &Ancillary Services
•
Civil works & Buildings
•
Security Services
Personal management
The CEB during the year under review continued to provide a conducive working
environment for all its employees and encouraged them autonomy, creativity and
responsibility in them work. The following functions continued to be carried out by the
Personnel Branch of the CEB while other Human Resources (HR) functions were carried
out by the HR units of the respective Divisions.
• Recruitment of employees to the permanent cadre.
• Promotions and disciplinary matters of employees
• Formulations of HR policies
62
• HR administration of all employees of Branches.
The total number of employees in CEB as at the end of 2013 was 16,326 and 412 personnel
were recruited during the year 2013, while 795 Employees left employment due to
retirement, resignation, etc. The consumer to employee ratio increased from 298 in 2012 to
319 at the end of 2013.
3.3.1 Welfare Unit
A network of Circuit Bungalows is maintained by CEB, at important locations such as
Hatton & Bandarawela in the cool climes and in religious/archaeological cities such as
Anuradhapura, Minneriya, Kandy, Kataragama and Jaffna. This facility is one of the major
benefits available to the employees which they can make use of when on holiday. Continuous
improvements are being made to the facilities provided at these bungalows with a view to
providing the best service to the occupants.
3.3.2 Security Section
The Security Section is responsible for ensuring safety of all vulnerable locations and CEB
premises including power stations, reservoirs and the office of the Ministry of Power &
Energy. Four Security Units are deployed for the security of the main Divisions of CEB
namely Generation, Transmission, Distribution and Projects.
3.3.3 Training Branch
Over the years Training Branch has taken steps to build up a competent work force through
education, training, skills development of the employees so that they become capable of
carrying out their work effectively in line with a modern integrated industry. CEB Training
Centre, Piliyandala is famous training center for power sector employers.
3.3.4 5S System
CEB uses 5S system very effectively to do their all the works very efficiently. The whole
CEB premises are arranged according to the 5S system. 5S is workplace management where
the work area and workplace are organized to minimize the loss of time and the use of
movement.
5S is much more than “a place for everything and everything in its place”. 5S comprises five
principles to make people highly efficient and effective in doing their work.
Sort -Keep near you only what you regularly use

Straighten -Find exactly what you need to use in less than 30 seconds

Shine -Have your workplace and equipment ready for immediate use
63

Standardize -Everyone does each job in the same way and is challenged to improve
it

3.4
Sustain -Everyone does their part to foster a safe, efficient and effective workplace
Safety Management
In any organization's safety of the workers or personals is the first thing which concerns in
operation. And the safety of the equipment is concerned as the second. I could learn about
safety instructional of site operation and maintenance work. All engineers, electrical
superintendents, workers and helpers follow site safety instruction at the site and power
plants. Transmission tower climber uses special safety tool kit for their safety.
3.4.1 Safety Precautions
All circuit breakers, isolators, reclosers, load break switches, sectionalizers and Distribution
substations were kept under lock and key. Only the authorized persons who are provided
with a master key have access to them.
Following are the most important safety precautions that need to be taken, when working on
apparatus, equipment connected to a medium and higher voltage system, considered as dead:
(a) Isolation of the system, plant, apparatus on which work is to be carried out from the
remainder of the system and also from all infeeds such as embedded generators, selfgenerating plants and equipment, using visible isolation devices that have to be kept locked
in the isolated position
(b) Discharging and earthing the system/plant/apparatus on which work is to be carried out,
by way of providing a connection with an approved earthing device, where practicable
keeping the same locked and immobilized.
It is not always possible to make LV equipment/apparatus dead and hence work on such
apparatus were carried out as if they are live, unless such equipment is proved dead. Where
applicable, suitable precautions were taken by screening or other means to avoid danger from
inadvertent contact with live conductors. Work on live apparatus were only be undertaken
by competent persons.
64
Chapter Four
4
4.1
Summary and Conclusion
Summary
During 12 weeks of my training programme in Ceylon Electricity Board, I was able to get
a thorough knowledge about new technical things and also to how to behave at the industry
and how to survive at the industry. Throughout this report, it is described that the things what
I train during my training period of 12 weeks. Also, I gained a lot of technical experience
about power engineering sector.
I was able to identify what are the equipment of the power system of Sri Lanka and technics
at the generation and transmission divisions and also visited Lakvijaya and Kotmale power
plants which are hubs of Sri Lankan power sector. Also, I studied about generation and
transmission planning methodology. In the system control center, I was familiar with that
frequency controlling method, basic principles of power system operation and software such
as PSS and SDDP which are used for operational planning and dispatch of s power system.
I also got a chance to familiar with the regional and operations management processes with
the staff of Ceylon Electricity Board. During this period, I got the chance to participate
several training Session those are conducted specially for Trainees by the Engineers who
are working at the CEB.
4.2
Conclusion
Ceylon Electricity Board is one of the finest training places for any of the undergraduates
who are interested in power sector and related technologies. It provided me a very good
opportunity to obtain a good theoretical, technical and management knowledge on power
system.
The aim of the industrial training, which I underwent during the last period, was to gain
practical knowledge and professional experience with the required theoretical background.
It was a great experience to be a trainee at Ceylon Electricity Board the foremost government
institute in Sri Lanka with modern technology and well-qualified staff.
Apart from technical knowledge, the soft skills that we were exposed to will be invaluable
for our future lives. Working with staff of different statuses, collectively working as a team,
handling customers, documentation and reporting, punctuality, adjusting to the office culture
are some of the skills we developed during these three months.
Especially the engineers and the technical Officers are very helpful and friendly and we
could reach them for any clarification regarding the training without hesitation. Nobody went
65
away when we had a problem. They always try to take us whenever they are going to operate
equipment or fault correction or check the site. All of them gave me good support to success
my industrial training.
Also, I must appreciate National Apprentice and Industrial Training Authority (NAITA) and
Engineering Education Center (EEC), Faculty of Engineering, University of Ruhuna for their
help to make my industrial training success.
Finally, I can say that I completed my Industrial training period successfully, I got lots of
experience and guidance for my future career.
66
Abbreviation
AAC - All Aluminum Conductors
ABC - Arial Bundle Conductor
ABS - Air Brake Switch
ACSR - Aluminum Conductor Steel Reinforce
ADB - Asian Development Bank
AGM - Additional General Manager
AIS - Air Insulated System
AM -Asset Management
AVR - Auto Voltage Regulator
BFP
-Boiler Feed Pump
BFPT -Boiler Feed Pump Turbine
BMCR -Boiler Maximum Continuous Rating
BST -Bulk Supply Tariff
CB - Circuit Breaker
CE - Chief Engineer
CEB - Ceylon Electrical Board
CHP -Coal Handling Plant
COND- Condenser
CPC -Ceylon Petroleum Corporation
CPP -Coal Power Plant
CT - Current Transformer
CVT - Capacitor Voltage Transformer
DC - Direct Current
DDLO - Drop Down Lift Off
DGEU-Department of Government Electrical Undertakings
DGM - Deputy General Manager
DL -Distribution Line
DRTR -De-aerator
DSM - Demand Side Management
DT - Distribution Transformer
EBPT- Extraction Back Pressure Turbine
ED-Economic Dispatch
67
EE - Electrical Engineer
EIA - Environmental Impact Assessment
EMS-Energy Management System
ES - Electrical Superintendent
ESP - Electrostatic Precipitator
EXIM - Export and Import Bank of China
FDF- Forced Draft Fan
FGD -Flue Gas De-Sulfurizer
FOR - Forced Outage Rate
GDP - Gross Domestic Product
GIS - Gas Insulated Substation
GIS-Gas Insulated Switchgear
GM - General Manager
GoSL -Government of Sri Lanka
GS - Grid Substation
GT - Gas Turbine
GT-Generator Transformer
GWh- Giga Watt hour
HP- High pressure
HPH -High Pressure Heater
HPP - Hydropower Plant
HPT- High Pressure Turbine
HQ -CEB Corporate Headquarters
HR -Heat Rate
HRSG - Heat Recovery Steam Generator
HT - High Tension
IDF -Induced Draft Fan
IEC - International Electrotechnical Commission
IPP - Independent Power Producer
IPT -Intermediate Pressure Turbine
JICA - Japan International Cooperation Agency
kVA -Kilo Volt Ampere
LA- Local Authority
LBS - Load Break Switch
68
LDC - Load Duration Curve
LECO - Lanka Electricity Company
LF - Load Factor
LP - Low Pressure
LPH - Low Pressure Heater
LPT -Low Pressure Turbine
LT - Low Tension
LTGEP - Long Term Generation Expansion Plan
LV-Low Voltage
LVPS -Lakvijaya Power Station
MCR- Maximum continuous output
MCW- Main Cooling Water
MOCB-Minimum Oil Circuit Breakers
MVA - Megavolt Ampere
MW - Megawatt
NAITA- National Apprentice and Industrial Training Authority
NCRE -Non-Conventional and Renewable Energy
NLPS - New Laxapana
O&M - Operation and Maintenance
OCCW -Open Cycle Cooling Water
OLPS - Old Laxapana Power Station
OLTC-On Load Tap Changers
ONAF - Oil Natural Air Force
ONAN - Oil Natural Air Natural
PAF -Primary Air Fan
PF - Plant Factor
PLCC- Power Line Carrier Communication
PPA - Power Purchase Agreement
PSS/E - Power System Simulation
PT-Potential Transformers
PUCSL-Public Utilities Commission of Sri Lanka
RC - Reinforce Concrete
SCADA-System Capture and Data Acquisition
SCC - System Control Centre
69
SDDP - Stochastic Dual Dynamic Programming
SEA-Sustainable Energy Authority
VT - Voltage Transformer
WCP-West Coast Power
70
Reference

Ceylon Electricity Board, (2014). “Long Term Generation & Expansion Plan,20112025,” Transmission and Generation Planning Branch, Transmission Division,
Ceylon Electricity Board, Sri Lanka.

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Electricity Board Annual Report 2013,” Mahaweli Complex, Ceylon Electricity
Board, Kandy.

Ceylon Electricity Board. (1997) “Strain Insulators for LV & MV Overhead
Distribution Lines, CEB Standard,” Ceylon Electricity Board, Colombo.

Ceylon Electricity Board. (2008-2014). “Annual Report,” Ceylon Electricity Board,
Colombo.

Ceylon Electricity Board. (2008-2014). “Statistical Digest,” Ceylon Electricity
Board, Colombo.

Ceylon Electricity Board. (2014). “System Controls & Operations Annual Report
2014,” System Control Center, Ceylon Electricity Board, Sri Lanka.

Ceylon Electricity Board. “Generator Interconnection of Sri Lanka,” Ceylon
Electricity Board, Colombo.

Electric Power Development Co., Ltd. (2015) “Development Planning on Optimal
Power Generation for Peak Demand in Sri Lanka,” Japan International
Cooperation Agency, Tokyo.

Electric Power Development Co., Ltd., Nippon Koei Co., Ltd. (2004) “Study of
Hydropower Optimization in Sri Lanka,” Japan International Cooperation Agency,
Tokyo, Japan.

Gunawardena, M., Hapuarachchi, C., Haputhanthri, D., and Harshana, I.,
“CapacityLimit of the Single Largest Generator unit, to Maintain Power System
Stability through a Load Shedding Program,” Department of Electrical Engineering,
University of Moratuwa, Moratuwa.

Harbin Turbine Co. Ltd.,” Installation and operation manual of Harbin Steam
Turbine for Puttalam Coal Power Project, Sri Lanka,” Harbin Turbine Co. Ltd,
China.
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
Nippon Koei Co., Ltd. Tokyo Electric Power Services Co., Ltd. Sojitz Research
Institute, Ltd. (2012). “Data Collection Survey on Electricity Supply System
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Cooperation Agency, Tokyo.

Public Utilities Commission of Sri Lanka,(2014).“Generation Performance in Sri
Lanka 2014,” Public Utilities Commission of Sri Lanka, Colombo.

Sri Lanka Sustainable Energy Authority., “Sri Lanka Energy Balance 2007 An
Analysis of Energy Sector Performance,” Sri Lanka Sustainable Energy Authority,
Colombo.

Tadashi I. (2006). “Master Plan Study on the Development of Power Generation and
Transmission System in Sri Lanka Final Report,” Japan International Cooperation
Agency, Economic Development Department.
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Tharangika B., Asanka S. R., Sisil P. K. and Lidula N.W.A. (2013). “A New Scheme
of Under Frequency Load Shedding and Islanding Operation,” Annual Transactions
of IESL, 290-296.
72
APPENDIX 1
POWER PLANTS IN SRI LANKA
I
II
III
IV