SESCO

SESCO TRANSMISSION SYSTEM
INFORMATION BOOKLET
SESCO TRANSMISSION
……. THE RELIABLE
POWER CONNECTION
THE RELIABLE POWER CONNECTION
PROVIDING A BRIGHTER FUTURE
SESCO TRANSMISSION SYSTEM
INFORMATION BOOKLET
CONTENTS PAGE
1. INTRODUCTION 1
2. OVERVIEW OF SESCO TRANSMISSION SYSTEM 1-4
2.1 TRANSMISSION SYSTEM

2.2 GENERATING PLANTS
2.3 SYSTEM DATA AND INFORMATION
3. THE MANAGEMENT AND OPERATION OF SESCO TRANSMISSION 5-8

SYSTEM
3.1 TRANSMISSION DEPARTMENT ORGANISATION STRUCTURE
3.2 GRID SYSTEM SECURITY
3.3 ASSET MANAGEMENT
4. OVERVIEW OF DIVISIONS IN TRANSMISSION DEPARTMENT 9-16
4.1 GRID SYSTEM OPERATION DIVISION

4.2 SUBSTATION OPERATION DIVISION
4.3 TRANSMISSION LINE OPERATION DIVISION
4.4 PROTECTION, CONTROL AND INSTRUMENTATION DIVISION
4.5 SUBSTATION AUTOMATION AND SCADA DIVISION
4.6 COMMUNICATION DIVISION
5. QUALITY OBJECTIVES OF TRANSMISSION DEPARTMENT 17-19
6. SYSTEM PERFORMANCE 20-22
7. DEVELOPMENT OF SESCO TRANSMISSION SYSTEM 23-24

7.1 SYSTEM DEVELOPMENT
7.2 FUTURE PLANS
8. TECHNICAL RESOURCES AND SERVICES AVAILABLE 25
9. TRANSMISSION DEPARTMENT MANAGEMENT TEAM 26
Enquiry : Head (Transmission)

Transmission Department
3rd Floor, Wisma SESCo
Petra Jaya, 93673 Kuching
Sarawak, Malaysia
Tel : 082-491360
Fax : 082-444633
E-mail : transmission@sesco.po.my
Website : www.sesco.com.my
1. INTRODUCTION
The SESCo Transmission System is critical component of the SESCo Power System, very
much akin in importance to the backbone and artery in the human body. Reliability of the
Transmission System therefore has a very major impact on the State’s economic activity and
ultimately customer satisfaction.
To deliver the level of reliability and security of supply required, the transmission system is
built to the highest standard, and must be maintained and operated also in accordance with
utility best practices. It is our vision to be the Number One in power delivery in the country,
and to be benchmarked among the best transmission system provider in the world.
This Booklet is a compilation of useful information on the SESCo Transmission System for
the benefit of SESCO customers and users of the Transmission System. It contains a brief
description of the SESCO Transmission Department as its Custodian and System Operator,
highlighting its products, goals and objectives.
To provide the reader with an insight into how the System is maintained and operated, the
relevant information of the six Divisions of Transmission Department is presented. This
covers the main objectives and functions of each Division. Relevant key performance indices
are also included to show the performance of the System and the supporting facilities.
2. OVERVIEW OF SESCO TRANSMISSION SYSTEM

Extra High Voltage (EHV) Transmission brings about many benefits to a growing electric
power system distributed over a wide geographical area. By providing an interconnection
between generation plants and load centres which are often separated by long distances, it
allows for the common sharing of available resources, optimisation in operations and mutual
support between areas, all of which will bring about cost savings, increased efficiency and
reliability of supply to the interconnected areas.
2.1 Transmission System

The first 216km long 275kV transmission line from Batang Ai to Kuching, commissioned in
1985, marked the beginning of EHV transmission in Sarawak. Together with the mammoth
Batang Ai Hydroelectric Scheme, it signified the quantum leap taken by SESCO in the field
of electric power system engineering and other state of the art technologies which are
associated with its development.
Subsequently, the 275kV network was extended at Engkilili eastward to Sibu, Bintulu and
Miri in 1988, 1991 and 1997 respectively. Presently the Transmission Systems consists of
765km of 275kV and 128km of 132kV transmission lines, fifteen 275/132kV Substations.
1
2.2 Generating Plants

The Transmission System interconnects 6 main Power Stations of a total capacity of 819
MW, operating on 4 different fuels, namely oil, gas, coal and hydro. Please refer to Figure 2
below. Out of these 6 Power Stations, 2 are owned by Independent Power Producers (IPP)
with a combined capacity of about 320MW.
Each generating unit has its own unique characteristics in operation mode, dynamic response,
operational and fuel cost constraints.
Power Fuel No of Available Normal Mode

Stations Type Units Capacity (MW) of Despatch
Kuching LFO 4 46 Base/Medium/Peak

(TAR PS) Dieseline 2 68 Peak
Kuching (SPC) Coal 2 100 Base
Btg Ai Hydro 4 94 Medium/Peak
Bintulu
(SESCO) Gas 6 192 Base/Medium
(SPG) Gas 2 220 Base/Medium
Miri Gas 8 99 Base
Total 28 819
A summary of the generating units at each Power Station
2
The thermal plants are operated on a baseload mode to minimise start/stop cycles but are
more costly in terms of fuel consumption. The hydro plants are despatched to meet medium
and peak demands; however, the hydro reserve is dependent on the water inflow into the
reservoir and hence it requires good management. Plants are despatched in the economic
merit order as far as possible; to minimise total cost of production. However, in some cases,
security considerations dictate that more expensive generation be despatched selectively.
SESCO Tun Abdul Rahman (TAR)

Oil-fired Power Station (total 106 MW)
First Commissioned in 1978
SESCO Batang Ai
Hydro Power Station (4X23.5MW)
Commissioned in 1985
SESCO Bintulu (Tjg Kidurong )

Gas-fired Power Station (6X34MW)
First Commissioned in 1991
Sejingkat Power Corporation (SPC)

Coal Fired Power Station (2X50MW)
Commissioned in 1997
The thermal Power Stations store sufficient stock of primary and backup fuels to reduce its
dependency on fuel delivery from the suppliers. All Power Stations, with the exception of
Sejingkat Power Corporation, are capable of blackstarting.
Careful planning and management are required to ensure an adequacy of supply at all times,
while satisfying all system conditions. Optimisation and least cost production planning are
continually done.
3
2.3 System Data and Information

The connection of Transmission System and Generation Plants, commonly referred to as the
‘SESCO Grid System’ has many unique characteristics associated with a relatively small
power system distributed over a large geographical area. Factors such as operational
constraints, dynamic system stability, possible disturbances from environment, eg. lightning,
vegetation, animals have to be carefully managed to ensure that the reliability and quality of
supply are not jeopardised.
There are 5 major load centres sparsely distributed throughout the State, with a combined
peak demand of 546 MW and energy demand of 3,412 GWH for 2001. The fuel cost to
produce this amount of electricity is about RM 209.5 million. This excludes the costs of the
operation and maintenance of the plants.
The average growth rate for SESCO for the last five years has been about 10% and this figure
is expected to be maintained for the next 5 years, as shown in below.
Generation Mix for Sarawak 1985 - 2006

6,000
G eneration M ix 2000 FORECASTED

FIGURES
5,000 Coal Hydro
16% 15%
Oil
4,000 8%
ACTUAL
FIGURES
GWh
Gas
3,000
61%
2,000
1,000
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Hydro Gas Oil Coal
The Transmission System has the capacity to meet the present needs and with the ongoing
development, it is well poised to cater for the future needs of SESCo’s customers. With the
criteria of N-2 and N-1 for capacity planning in the generating plants and transmission system
respectively, there is a guarantee of adequate supply to SESCO customers at most locations in
the State.
With the upcoming 2,400 MW Bakun Hydroelectric project expected to be operational by

2006, technical planning studies are underway to look into its integration to SESCO’s and
Sabah Electricity Supply Board (SESB)’s systems.
4
3. THE MANAGEMENT AND OPERATION OF SESCO TRANSMISSION SYSTEM
The Head Office of the SESCO Transmission Department

is housed on the 3rd Floor of Wisma SESCO in Kuching.
The nerve centre, State Despatch Centre (SDC) is located
on the 1st Floor.
The Transmission Department in SESCO is the Custodian and System Operator of the SESCO
Grid System.
The Products of the Transmission Department are:
i. The provision of Transmission System including Grid System supervision and control.
ii. The provision of in-house telecommunication, substation automation and SCADA

infrastructure and services.
iii. The provision of support and maintenance services for system protection, control and
instrumentation.
The Goals of Transmission Department are:
i. To effectively build, maintain, operate and control the Grid System, delivering electricity
which meets the requirements of SESCO customers.
ii. To effectively build and maintain telecommunication, substation automation and

SCADA facilities and services to meet the needs of SESCO business processes.
iii. To provide quality technical expertise in EHV substation and transmission line,
protection, control, instrumentation, telecommunication, substation automation and
SCADA engineering, and power quality appraisal in a timely manner which meet the
needs of internal and external customers.
5
3.1 Transmission Department Organisation Structure
The Transmission Department presently has a strength of 127 personnel, consisting of 31

engineers, 90 technicians and 6 office staff. Most of the personnel are based in the SESCO
Head Office at Wisma SESCO, with some site operations staff based at strategic locations
along the transmission line route.
The Organisation Structure of Transmission Department is shown below with the primary
functions of the six Divisions:
Head
(Transmission)
Office of Head
(Transmission)
Office Support &

Administration
Manager Manager Manager Manager Manager Manager

(Substation Automation (Communication) (Protection, Control (Grid System Operation) (Transmission Line (Substation
& SCADA) & Instrumentation) Operation) Operation)
SCADA Communication PCI Equipment Operational Transmission EHV Asset

Facilities Facilities & & Facilities Planning Lines Asset Management
Management Services Management
Energy Project Project Generation Wayleave Project

Management Management Co-ordination Despatch Coordination
System Testing & Testing &
Commissioning Commissioning
Operations Communication Relay System Project Substation

Training Network Coordination Monitoring & Coordination Manning
Simulator Maintenance Control Testing &
Commissioning
Substation Consultation Fault Level Outage Civil Works Substation

Automation Services Studies Coordination Maintenance Maintenance
Facilities
Project Disturbances Simulation Lines Technical

Management Recording & Studies Maintenance Services
Analysis
SAS
Maintenance
6
3.2 Grid System Security
The Grid System has been designed with 100% redundancy (N-1) for all major components
as shown in the Figure below.
Redundant bus
isolator design Double-circuit transmission that can
accommodate N-1 equipment outage
contingency.
Generator, transmission, power

transformer can tap on to either
main or reserve busbar
33kV 11kV Ring-Main Unit

[RMU]
275kV
Circuit-breaker Ring-Main Unit

Redundant power normally open [RMU]
transformer
Main bus Reserve bus To tee-off line or
local transformer
or customer
Redundancy inherent in system design at generation and
transmission level in SESCO power system
Grid System security is paramount. In the operation of the Grid System, various measures
are being taken to ensure this :
• Power system simulation studies and analysis: Forward planning is continually done and
various credible scenarios are studied carefully
• Multiple sources of generation in the System and diversity of fuel types
• Generation operating reserve; Spinning reserve is provided for the largest generating unit
online at all times
• Highly sophisticated protection system to clear faults expediently to minimise secondary
impact on the System
• Strict control and supervision of maintenance and testing activities
• Close communication / coordination with large customers and users of the Grid System
• Operational contingency measures such as nine-stage underfrequency load shedding
scheme
• Fast restoration of supply through SCADA in the event of tripping
• Disturbance recording are done at various locations in the System for post-disturbance
analysis and corrective actions
• Lightning tracking system will soon be installed to alert SDC operators on approaching
thunderstorm and to take any precautionary actions, including shifting generation if
necessary
7
3.3 Asset Management
Today, the net operating assets of the Transmission System are valued at about RM758
million. The way the assets are managed is fundamental to stakeholder value and business
success. This is put in place by the 5 year Strategic Transmission Asset Management Plan
(STAMP) adopted by the Transmission Department in 2000.
The components of STAMP are :

Shareholder Customer
Category Activity
(MVA Impact) (Benefit Impact)
Asset Creation Development Capital Employed Supply Security
(new construction) (Fixed Assets) Supply Quality
Augmentation Terminal value
(Upgrade)
Asset Disposal Decommissioning

Mothballing
Dismantling/sale
Operation Configuration Revenue Price Flexibility

Protection Transport Costs Product Quality
Switching Asset life Delivery achievement
Stewardship Replacement Sustainability Supply Reliability

(Predictive) Refurbishment costs (long run Supply Quality
Modification average
Inspection/servicing Asset life
Condition monitoring
Fault Response Diagnostic Operating costs Supply Restoration
(Corrective) Supply (Actual Expensed) Customer Service
Restoration
Repair
The asset strategy links the desired performance and current condition of the asset with the
work required to achieve these goals. The key outputs of an asset strategy are :
• Defined levels of performance such as asset life, availability, reliability and efficiency
(losses)
• A long term workload described in work categories such as refurbishment, replacement,

overhauls and inspections.
• A matching resource requirement by major skill groups
• A cash flow forecast for the plan
8
4. OVERVIEW OF DIVISIONS IN TRANSMISSION DEPARTMENT
4.1 Grid System Operation (GSO) Division
The main objectives of the Grid System Operation Division are:
• To effectively operate and control the SESCO Grid System to ensure reliability, security
and quality of supply to our customers.
• To despatch the generation for the SESCO Grid System according to least cost options
and optimal generation mix.
• To provide expertise and services to other Divisions on matters related to the SESCO
Grid System and its development.
Within the Grid System Operation Division,

there are three main Sections:
The Operational Planning Section covers

operational planning ranging from the immediate
term (1 day) to medium term (5yrs) horizon. This
includes the Grid Generation Planning,
coordination of shutdowns and tests on
generation, transmission and distribution
components. Computer programs such as P-Com
and P-Week are used for the optimisation of Power system simulation
production. The Annual Grid Generation Plan
(AGGP) is produced at the beginning of each
year and is reviewed quarterly.
The Technical Service Section covers the

simulation studies, contingency planning,
disturbance monitoring, trouble shooting, training
and support to SDC pertaining to the operation of
the Grid. The computer programs PSSE is used to
carry out the simulation. This Section also does
system-side PQ monitoring and liaise with large
industrial customers on PQ issues.
The State Despatch Centre (SDC) is a 24 hour Typical SCADA screen

manned Control Centre housed in Wisma
SESCO, Kuching responsible for the realtime
monitoring, supervision and control of the
System, and generation despatching using the
state of the art SCADA technology. All the major
Substations from 11kV to 275kV are monitorable
and controllable from SDC.
SDC works very closely with the Control Centres

of the Grid connected Power Stations and
Regional Despatch Control (RDC) distributed
throughout the State, coordinating all major
works such as shutdown, switching and supply Typical daily load pattern and
restoration. generation despatch
9
4.2 Substation Operation (SSO) Division
The main objectives of the Substation Operation Division are:
• To maintain the asset of EHV facilities for safe and reliable operation at all times.
• To achieve mean outage duration of < 580 min. for forced and planned outages.
• To achieve forced and planned outage rates of <0.4 and <0.76 per 100 MVA respectively.
• To achieve 3-Star rating for all EHV substations within the next 2 years.
The SSO Division is the custodian of all EHV Substations in the SESCo Grid System,
covering all equipment within the perimeter fencings. However, the 33kV and 11kV
Switchgear for outgoing feeders in these Substations are operationally under the respective
Regions or Power Stations according to agreed operational boundaries.
A 'Permit to Enter Substation' must be obtained from

SSO Division prior to enter, except for emergency
cases such as breakdown, faults.
The type of switchgears ranges from outdoor SF6

insulated circuit breakers to indoor Gas Insulated
Substation (GIS). For major Substations, a double
busbar configuration is adopted with dual
redundancy provided for major components.
275/33kV transformer
Two Specialist Support groups have been formed to:
i. carry out maintenance repair works
ii. supervising and commissioning of projects.
Though not all EHV stations are manned, the

substation operators will conduct a daily routine
visual inspections and monitor the status of all EHV
station equipment. At present there are 5 operations
teams located in the following Substations:
Manning of EHV substation • Muara Tabuan Substation, covering Kuching

Outer Ring Substations
• Engkilili Substation, covering Engkilili /Batang
Ai/ Betong Substations
• Kemantan Substation, covering
Kemantan/Sarikei/Tjg Manis Substations
• Deshon Substation, covering Oya/Sibu/Bintulu
Substation
• Tudan Substation
Apart from the normal operation duties, these

275kV SF6 circuit breakers operators are supporting the Specialist Support
group in carrying maintenance works whenever
assigned. Regular maintenance works include
functional checks on switchgear, OLTC
maintenance, purification of transformer oil,
dissolved gas analysis, tangent delta test.
10
4.3 TRANSMISSION LINE OPERATION (TLO) DIVISION

TLO carries out maintenance for all the 275kV and 132kV transmission lines stretching about
765 km and 128km respectively from Kuching to Miri with linesmen located at the major
towns. To meet the needs of the customers, TLO must ensure maximum reliability and
availability of all these transmission lines. The objectives of the division are :
• To achieve the required outage rate and mean outage duration performance indices
comparable to other utilities in the region.
Outage type Outage rate (per 100 cct km) Mean outage duration (mins)
Forced 2.0 100
Planned 1.0 500
• To restore supply for one circuit within 2 weeks on the event of a damage tower
A 275kV suspension tower Aerial lineswork in progress A 275kV tension tower

The main 275kV line linking Kuching and Miri is built of steel lattice towers supporting 2
circuits, each comprising 2 ACSR conductors. The 132kV tee-off lines from the main line are
built on either lattice towers or monopoles and with similar formation. The lines have been
designed to international standards of safety standards eg. mechanical strength, safety
clearances and electromagnetic field interference.
The main challenges to the transmission line performance come from the environment eg.
lightning, vegetation and animals. As the isokeraunic level is very high (180 thunderstorm
days per year), special design features are incorporate in the line design to withstand
lightning strikes eg. zero angle shielding, low tower footing resistances, differential impulse
insulation, belian crossarms for suspension towers. As most of the faults are transient in
nature, the single pole auto reclosure had been successful in a number of operations.
Sufficient ground clearances (minimum 6.5m) and easement width (40m) are ensured
throughout the route of the transmission line, to minimise the likelihood of vegetation
encroaching on to the conductors.
The main activities carried out each year comprise civil and electrical inspection of the tower,
conductor and easement clearing. Tower top inspection, live line insulator checking, checks
on tower footing earthing and minor repair work are conducted by the linesmen while civil
foundation repair, hillslope protection and easement clearing by Contractors. TLO Division
has a set of emergency response system (ERS) structures to mitigate against any tower
failure.
In addition to maintenance of the lines, TLO Division also provides supervision of project
works done by Contractors.
11
4.4 Protection, Control and Instrumentation (PCI) Division
The Protection, Control and Instrumentation

(PCI) Division is responsible for the protection in
the EHV transmission and distribution systems.
PCI Division is divided into 2 units of
maintenance team-one unit for the transmission
system and the other for the distribution system.
For the distribution system, support and frontline
maintenance personnel are provided by the
respective regions.
This Division also provides technical support and

maintenance services for other Departments and
Transmission Line Disturbance Record the implementation of new substation projects
upon request.
The main objectives of the PCI Division are:
• To effectively maintain the protection

system to meet the availability
requirement of the SESCO Grid System
including all the distribution substations at
all times.
• To provide quality technical services on

protection, control and instrumentation in
a timely manner to meet the needs of
customers.
• To improve and maintain the performance A Dynamic System Monitor (DSM) Record
of the protection system of the Grid
System to a reliability of at least 90%.
• To eliminate incidences of double circuit

outage on the EHV Transmission System
by the implementation of the fast speed
single pole autoreclosing scheme.
• To prevent maloperation of protection in

the distribution system due to protection
non-discrimination and protection
equipment failure.
• To assess the current protection scheme in

the EHV transmission and the distribution
systems and to replace or upgrade the
aging relays where the cost of Equipment testing in progress
maintenance are very high.
The ASPEN Computer program is used for fault level calculation and relay coordination.
Computerised injection test sets are used for the testing of relays, CTs and VTs.
12
4.5 Substation Automation and SCADA (SAS) Division
Supervisory Control and Data Acquisition (SCADA) is the key to effective control of any
power system as realtime information e.g. as status of equipment, alarms, loadings, voltage
and frequency can be brought back to a central location and displayed to the Operator. The
Operator can then make the correct control decisions by remotely operate the equipment.
The main objectives of the Substation Automation and SCADA Division are:
• To provide the Substation Automation and SCADA facilities, in a timely and effective
manner, to meet the needs of the operation of SESCO power system.
• To provide technical support and services on project management, installation, testing and
commissioning and maintenance of Substation Automation and SCADA systems.
• To establish, define and update PPGs and standards of the Substation Automation and
SCADA systems to meet the needs of SESCO
Application User User User Remote Console Development RDIGS

Application Mimic
Processor 2 Interface 1 Interface 2 Interface 3 Server Node Server
Processor 1 Projection
Redundant Ethernet
Redundant Ethernet
GPS
Bridge
Laser X-term X-term
Printer FTP
Logger 1 Logger 2 Server
DAC Node
State Despatch Center
SDC
2 Mbps
Channels
Kuching Miri
RTUs RDC Sibu Bintulu RDC
RDC RDC
13
There are three Sections in the SAS Division :
• SCADA Facilities and User Support
This Section provides the SCADA/EMS facilities together with the support and services
on project management, installation, testing and commissioning of SCADA/EMS
systems. It also establishes SCADA/EMS PPGs and standards.
• Facilities Maintenance
This Section provides maintenance services to both Substation Automation and

SCADA/EMS assets. It ensures the assets are functioning as intended at all times.
• Substation Automation Support

This Section provides the facilities together with the support and services on project
management, installation, testing and commissioning of substation automation systems. It
also establishes substation automation facilities’ PPGs and standards.
Testing of RTU equipment EMS Training in progress
The existing SAS systems comprise of:
SCADA systems
• Fully redundant master system in SDC to support SCADA facilities for all EHV, 33/11kV
and major 11kV substations and power stations. This master system is inter-linked to
Kuching, Sibu, Bintulu and Miri RDCs’ master systems.
• Four master systems in Kuching, Sibu, Bintulu and Miri RDCs to support SCADA facilities
for localised EHV, 33/11kV and major 11kV substations and power stations.
• Two mini master systems in Lundu and Lawas to support SCADA facilities for localised
11kV substations and power stations.
Remote Terminal Units (RTUs)

• More than 100 logical RTUs are installed in EHV, 33/11kV and major 11kV substations and
power stations, with a total point counts of exceeding 30,000 points including 5,000
supervisory control points.
Substation Control Systems

• Two substation control systems in Miri area.
14
4.6 Communication Division
The main objectives of the Communication Division are:
• To set up and maintain a reliable communication network throughout the SESCo system.
• To provide an efficient and cost effective communication network facilities and services
to meet the growing needs of SESCO power system operation and business
administration in the power utility environment.
The communication network comprises of various media and routes, namely:
• The fibre optic network covers all the Grid connected Regions. SDH channels are
operating at STM4 (622 Mbps) and STM1 (155Mbps) level, linking all Despatch Centres,
major Power Stations, EHV Substations and Regional Offices. PDH channels are
operating at 2 Mbps, linking most of the 33KV substations and regional power stations.
• The Micro-Wave Radio link was set up between Wisma Sesco and Biawak 132 KV
substation. The link forms part of the fibre optic network.
• The Power Line Carrier (PLC) network was set up along the EHV Transmission Lines.
All the EHV Substations are linked up by PLC channels. The PLC channels are working
on 4 kHz baseband which can provide analogue speech and low speed data channel ( up
to 9600bps ).
• Pilot Cable network: Before the implementation of fibre optic network, the pilot cable
network was set up to link 33 KV substations. The pilot cable channels can provide the
same 4 kHz baseband as PLC channels but with limited distance ( about 20 km ) due to
the attenuation effect of the pilot cable.
Discharge test on 48V battery
Signaling test for PLC equipment

Fibre optic network management
15
The network facilities support various applications in SESCO:
• Private Automatic Exchange (PAX) for SESCO internal telephone network which is
used for operations purposes, eg. despatch centres, power stations, regional offices,
substations, offices for operations personnel
• Public Automatic Branch Exchange (PABX): All PABXs have been linked up to form a
network. The extensions are installed in regional offices for administrative purposes
• Security surveillance System for Kuching Regional Office to monitor intruder alarms
for EHV Susbtations in Kuching region. The system will be extended to other regions in
phases.
• Data Communication Network: Data communication has been setup to link SESCO
offices for IS application
Network channel usage support are provided for other applications in SESCO:
• SCADA System
• EHV and 33kV line current differential protection
• EHV Substation monitoring
Communication channels from 64kbps to 2 Mbps are also available for other applications if
required.
16
5. QUALITY OBJECTIVES OF TRANSMISSION DEPARTMENT

The Quality Objectives of Transmission Department are:
i. Monitoring and Control of the Grid System

To operate SESCO transmission system so as to meet the following performance criteria:
Normal System Emergency System

Parameter
Operating Condition Operating Condition
Voltage variation ± 5% ± 10%
Frequency variation ± 0.5 Hz ± 1.0 Hz
Time error control ± 10 seconds ± 10 seconds
Note: Emergency condition involves the period subsequent to the tripping of a system
component and may last up to 1 minute until operator intervention.
The control of voltage is achieved by the following means:
• Control of excitation at relevant generating unit
• Control of onload tap changer of stepdown transformers at transmission delivery
points
• Switching of reactive compensation devices, eg. capacitor and reactor banks
SDC continually monitors the voltage fluctuation and activates the necessary control
actions to ensure that the voltage limits are within acceptable ranges. Dynamic System
Monitors (DSM) are located at 4 locations of the System to automatically record any
deviation of voltage.
The control of frequency and time control is achieved by controlling of the gas turbines at
Bintulu as they are baseload generation and fine control can be effected. By the middle of
2003, the Automatic Generation Control (AGC) will be in place to further improve the
secondary control of frequency.
ii. Grid Generation Despatch

To achieve target cost/kwh of energy delivered to the grid system by despatching
generation to the SESCO Grid in accordance with the operational practices of the
optimal utilisation of available generation resources.
iii. Power Reliability and Quality

System Transmission Delivery Point Performance (TDPP) ≤ 33 system minutes
Availability Transmission System Faults < 3 per year
Voltage dip incidents beyond SEMI curve
Power Quality
recorded at Tg. Kidurong 275kV & Muara Tabuan ≤ 2 per month
(Voltage dip)
132kV buses for grid fault
Outage Restoration tiem to EHV substations following an
≤ 30 minutes
Response Time interruption other than faulty equipment
Notes:
TDPP is a measure of weighted average supply availability in system minute; one
system minute being equivalent to one minute of total system supply unavailability.
SEMI : Semiconductor Equipment and Materials International
17
In accordance with Prudent Utility Practices, preventive measures are in place to prevent and
minimise the possibility of system disturbances and supply interruptions. The strategy is to
prevent system faults by the maintenance of equipment in tip-top conditions, control of online
tests on equipment and proper coordination of shutdown activities.
In the case of unavoidable faults, eg due to environment, the strategy is to clear the faults as
fast as possible with fast acting protective relays. This will help minimise the impact of
voltage dips to the customers and avoid the risk of system instability.
As with any power system, faults and supply interruption may still occur. Restoration with
the aid of SCADA system can be done remotely to minimise interruption time to the
customers. With the exception of equipment failure, the despatch of switching personnel to
site can be avoided, thus saving valuable time in the restoration process.
With the introduction of high tech sensitive equipment and process in industries, voltage dips
have become an issue. Internationally, standards for voltage quality are evolving, the latest
being SEMI curve which SESCO has adopted as the Standard. The Figure below shows the
comparison between the old CBEMA and ITIC curves with the SEMI curve.
IT IC CBEM A SEM I
100
90
80
70
% R a te d V o lta g e
60
50
40
30
20
10
0
1 10 100 1000 10000 100000
T im e in m s
SEMI Curve as compared to CBEMA, ITIC curves
Notes: ITIC: Information Technology Industry Council

CBEMA: Computer Business Equipment Manufacturers Association
18
iv. Asset Management
a. To improve and maintain the reliability of major transmission equipment so as to

meet the following targets:
EHV Type of Outage Rate Mean Duration

Equipment Outage Outage Factor
Duration
(min)
Forced < 2.00 per 100cct.km < 100
Lines
Planned < 1.00 per 100cct.km < 500
Forced ≤ 0.40 per 100 MVA ≤ 580 ≤ 0.06 %
Transformers
Planned ≤ 0.76 per 100 MVA ≤ 580 ≤ 0.2 %
b. To improve and maintain the availability of supporting equipment and facilities so as

to meet the following targets:
Division Type of Equipment Reliability

Protection Protection system ≥ 90%
Division Type of Equipment Availability MTTR

Pilot Cables system ≥ 99.9% ≤ 4 days
Communication PLC/FO system ≥ 99.9% ≤ 3 days
PABX/PAX System ≥ 99.9% ≤ 1 day
SCADA Master Station ≥ 99.8% ≤ 1 day
SAS
SCADA RTU System ≥ 99.6% ≤ 1 day
Note: MTTR: Mean time to repair
c. To increase asset turn from 0.18 to 0.26 by 2005 through improving asset utilisation
with improved value for money from capital expenditure.
d. To achieve value creation for the department in excess of WACC of 6% per annum.
e. To improve and achieve target labour productivity.
19
6. SYSTEM PERFORMANCE
The Transmission System has been built with the help of internationally experienced
Consultants and reputable Contractors in accordance to international standards and practices.
Local statutory and safety requirements are strictly adhered to at all phases of the
implementation in all components of the Transmission System.
Over the years, SESCO Transmission Department has acquired the technological knowledge
and skills to carry out the planning, design, operation and maintenance of the System. Prudent
Utility Practices are adopted at all times to ensure delivery of best performances of the
Transmission System at all times.
The performances of the various components of the Transmission System are shown in the
following tables:
i) Power Quality
Frequency Controlled by Bintulu Power Station to be within ±0.5 Hz

Time Control Within ±10 seconds.
Information obtained from the Dynamic System Monitor (DSM)
Voltage Dips
shows target of less than 2 times per month had been achieved.
SESCO had carried out a number of studies on Power Quality (PQ), the most recent one done
by Energex (Queensland, Australia) in 2000. From the 4 years of record at Muara Tabuan S/S
which is the transmission delivery point to Samajaya Free Industrial Zone in Kuching, there
were 46 voltage dips recorded, averaging 0.95 dips per month. Out of these incidents, 24 did
affect the customer in some way.
Impact Analysis for 1997 - 2000 Major Events Based on MUTB 33 kV Voltage
Customer Affected No Impact CBEMA SEMI
100
90
80
70
60
Voltage %
50
40
30
20
10
0
10 100 1000 10000
Duration ms
20
It can be noted that although some voltage dips were within the SEMI curve, the customers
were still affected, demonstrating that some customers’ equipment could have been more
sensitive that expected. The strategy would be for the customer to make his equipment less
sensitive to voltage dips while SESCO will work toward a better voltage conditions.
100
Sensitivity
Customer
80
Voltage %
60
SESCo Voltage
40
Conditions SEMI
20
0
10 100 1000 10000
Duration Milli-Seconds
Figure 10: Strategy to mitigate voltage dip problems
Cost effective solutions can often achievable through collaborative efforts with customers.
APPLY CUSTOM POWER

SOLUTIONS [Either Side
of Metering Point]
DESENSITISE
CRITICAL LOADS
[Customer Side) REDUCE NUMBER OF FAULTS
(System side)
Common solutions to PQ (voltage dip) problems
21
On the system side, SESCO had adopted a number of solutions to improve the level
of PQ performance, eg:
• Carry out intensive maintenance programs to minimise number of faults in the

transmission and distribution systems
• Reduce the impact of faults on sensitive loads by reconfiguring the system
wherever possible
• Reduce the impact of faults by reducing the fault current and expediting the fault
clearance
• Maintaining extensive database of cause and effect relationships for analysis and
corrective actions
• Providing more baseload generation in Kuching whenever required
ii) Power Reliability
a. The Transmission Delivery Point Performance
Year 1997 1998 1999 2000 2001

TDPP
170.99 9.35 77.33 49.04 1.65
(system minutes)
b. The average number of total 275kV and 132kV Transmission Line Trippings is
28.2 per year.
Year 1997 1998 1999 2000 2001
Trippings 22 19 17 53 30
The above figures consist of all trippings due to transient faults, eg lightning and
vegetation faults, non-line faults eg. substation equipment / relay failure, human
factors. Efforts had been made to reduce all these faults by replacing faulty
equipment, conducting reality checks and enforcing strict procedures for online tests.
iii) Power Restoration Time
Year 1997 1998 1999 2000 2001

Incidents < 45 minutes 4 1 1 4 5
Incidents > 45 minutes 0 0 2 5 0
Notes : Outages restored above 45 minutes were mainly due to equipment failure or
permanent fault. From 2001 onward, the target of 45 mins was reduced to 30 mins.
22
7. DEVELOPMENT OF SESCO TRANSMISSION SYSTEM
7.1 System Development
The demand in the Grid will continue to grow in the years ahead. The growth expected for
the next five years is as follows:
Year Peak Energy

(MW) (GWH)
2002 605 3702

2003 669 4098
2004 720 4458
2005 771 4775
2006 834 5133
There are currently projects being implemented to increase the capacity of the System to cater
for future needs. The main ones are;
• Betong 275/33kV 10 MVA Teeoff Project commissioned in October 2001, providing an

injection point to Betong and Saratok areas and alternative supply source to Sri Aman
• Bintulu - Tjg Kidurong 132kV 120 MVA Transformer Feeder Project scheduled to be
commissioned in May 2002, providing a bulk injection point to the Tjg. Kidurong
industrial areas in Bintulu.
• Oya – Salim 132kV 80 MVA Transmission Project scheduled to be commissioned by
2003, providing a bulk injection point to the Salim / Upper Lanang areas in Sibu
• Matang – Batu Kawa 132kV Transmission Line Project scheduled to be commissioned in
early 2002, providing supply to the new township at Batu Kawa in Kuching
• Kemena 275 kV Substation Project scheduled to be commissioned by 2004, providing a
new injection point to the Kemena Industrial Zone and a future connection to Bakun
To enhance the operation of the Grid System, the following projects are also implemented:
• Lightning Tracking System scheduled to be completed by March 2002, providing

advance warning system for the SDC despatchers
• SCADA based optimisation and training/simulation applications, consisting of Energy
Management System (EMS), Power Network Application (PNA) , Automatic Generation
Control (AGC) Operator Training Simulator (OTS), these will be completed in stages
before middle of 2003, providing increased capability to SDC despatchers and
enhancement to the overall operation of the Grid System
• Fibre Optic Channels to 33kV Substations, scheduled to be completed in stages, by Dec
2002, extending the LAN network and providing communication channels for digital
feeder protection systems.
• Upgrading of PAX Network, scheduled to be completed by 1st Quarter of 2002, providing

high speed links and solving the network congestion at Mambong substation.
• Implementation of the Enterprise Resource Planning (ERP) packages, scheduled for
completion by middle of 2002, providing computerisation of value-based management,
asset management, project development, materials and work management
23
7.2 Future Plans
To keep pace with Sarawak’s rapid development and growing demand for electricity, SESCO
continues to expand the State Grid System. SESCO is committed to a long term multi million
investment program to develop the transmission infrastructure to meet the customers’ future
needs.
Some of the plans in the pipeline are:
• Integration of the System with the 2400MW Bakun Hydro-electric Project, expected to
be operational by 2006 and an associated connection with Sabah Electricity Supply Board
(SESB) system
• Additional circuits to increase capacity and reliability of supply to the Kuching system
• Reactive power compensation in Oya and Mambong to increase power transfer capability
and improve voltage support
• Additional EHV Substations to provide bulk injection points to the regional distribution
system
Some of the other works which the Transmission Department are involved in are:
• Development of the State Grid Code, in conjunction with the State Government
• Feasibility study of the fibre optic connection from Sarawak to Peninsula Malaysia
24
8. TECHNICAL RESOURCES AND SERVICES AVAILABLE
SESCO Transmission Department is prepared to share its experiences and expertise in the
following areas with SESCO customers. Technical training, field services and consultancy
services can be arranged upon request.
i. Grid System Operation Division
• Power System Analysis

• Operational Planning
• Generation, Transmission and distribution outage coordination
• Dynamic System Monitoring
• Issues related to quality and reliability of supply
• Large customer connection
• Contingency plans
• Monitoring of system
ii. Substation Operation Division
• Maintenance of EHV Switchgear, transformer and ancilliary equipment

• Diagnostic test on power equipment
• Oil filtration
• Project design, management, supervision and commissioning
• Asset Management
• Safety and Competency
iii. Transmission Line Operation Division
• Maintenance of EHV Transmission Lines

• Project design, management, supervision and commissioning
• Emergency tower response
iv. Protection, Control and Instrumentation Division
• Fault level calculations

• Relay coordination
• Design, management and commissioning of PCI systems
• Testing of relays
• Troubleshooting on PCI systems
v. Substation automation and SCADA Division
• Provision of monitoring and control facilities

• Design, management and commissioning of SAS facilities
vi. Communication Division
• Provision of communication channels and network

• Design, management and commissioning of communication systems
25
9. TRANSMISSION DEPARTMENT MANAGEMENT TEAM
William Chin Thien Poh

Head (Transmission)
Tel: 082-491360
Fax: 082-444633
E-mail: williamchin@sesco.po.my
Jason Eng Yeon Khiang Mok Yuk Bio

Manager Manager
(Grid System Operation) (Substation Operation)
Tel: 082-491340 Tel: 082-491310
Fax: 082-444633 Fax: 082-444633
E-mail: jasoneng@sesco.po.my E-mail: ybmok@sesco.po.my
Philip Lim Tiong Hui Jong Chin Chyuan

Manager Manager
(Transmission Line Operation) (Substation Automation and SCADA)
Tel: 082-491321 Tel: 082-491350
Fax: 082-444633 Fax: 082-444633
E-mail: philiplim@sesco.po.my E-mail: ccjong@sesco.po.my
Chung Koi Main Ong Ngiok Siang

Acting Manager Acting Manager
(Protection, Control and (Communication)
Instrumentation) Tel: 082-491361
Tel: 082-491370 Fax: 082-444633
Fax: 082-444633 E-mail: ongns@sesco.po.my
E-mail: chungkm@sesco.po.my
26

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SESCO TRANSMISSION SYSTEM

SESCO TRANSMISSION SYSTEM

2. OVERVIEW OF SESCO TRANSMISSION SYSTEM 1-4

2.1 TRANSMISSION SYSTEM

3. THE MANAGEMENT AND OPERATION OF SESCO TRANSMISSION 5-8

4. OVERVIEW OF DIVISIONS IN TRANSMISSION DEPARTMENT 9-16

4.1 GRID SYSTEM OPERATION DIVISION

5. QUALITY OBJECTIVES OF TRANSMISSION DEPARTMENT 17-19

6. SYSTEM PERFORMANCE 20-22

7. DEVELOPMENT OF SESCO TRANSMISSION SYSTEM 23-24

8. TECHNICAL RESOURCES AND SERVICES AVAILABLE 25

9. TRANSMISSION DEPARTMENT MANAGEMENT TEAM 26

Enquiry : Head (Transmission)

2. OVERVIEW OF SESCO TRANSMISSION SYSTEM

2.1 Transmission System

2.2 Generating Plants

Power Fuel No of Available Normal Mode

Kuching LFO 4 46 Base/Medium/Peak

Kuching (SPC) Coal 2 100 Base

Btg Ai Hydro 4 94 Medium/Peak

Miri Gas 8 99 Base

SESCO Tun Abdul Rahman (TAR)

SESCO Bintulu (Tjg Kidurong )

Sejingkat Power Corporation (SPC)

2.3 System Data and Information

Generation Mix for Sarawak 1985 - 2006

G eneration M ix 2000 FORECASTED

Hydro Gas Oil Coal

With the upcoming 2,400 MW Bakun Hydroelectric project expected to be operational by

3. THE MANAGEMENT AND OPERATION OF SESCO TRANSMISSION SYSTEM

The Head Office of the SESCO Transmission Department

The Products of the Transmission Department are:

ii. The provision of in-house telecommunication, substation automation and SCADA

The Goals of Transmission Department are:

which meets the requirements of SESCO customers.

ii. To effectively build and maintain telecommunication, substation automation and

3.1 Transmission Department Organisation Structure

The Transmission Department presently has a strength of 127 personnel, consisting of 31

Office Support &

Manager Manager Manager Manager Manager Manager

SCADA Communication PCI Equipment Operational Transmission EHV Asset

Energy Project Project Generation Wayleave Project

Operations Communication Relay System Project Substation

Substation Consultation Fault Level Outage Civil Works Substation

Project Disturbances Simulation Lines Technical

3.2 Grid System Security

Generator, transmission, power

33kV 11kV Ring-Main Unit

Circuit-breaker Ring-Main Unit

3.3 Asset Management

The components of STAMP are :

Asset Disposal Decommissioning

Operation Configuration Revenue Price Flexibility

Stewardship Replacement Sustainability Supply Reliability

• A long term workload described in work categories such as refurbishment, replacement,

• A matching resource requirement by major skill groups

• A cash flow forecast for the plan

4. OVERVIEW OF DIVISIONS IN TRANSMISSION DEPARTMENT

4.1 Grid System Operation (GSO) Division