TNBT Seminar Paper

8/3/2019 TNBT Seminar Paper

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UNIVERSITI TUN HUSSEIN ONN MALAYSIA

I. COMPANY INFORMATION

ENAGA NASIONAL BERHAD (TNB) is the largest electricity

utility company in Malaysia. TNB’s core activities are in

the generation, transmission and distribution of electricity.

Currently, the TNB group has a complete power supply

system, including the National Grid which is energized at

132, 275 and 500 kV. The National Grid is linked via 132 kV

HVAC and 300 kV HVDC interconnection to Thailand and

230 kV cables to Singapore.

T

Fig 1 : Grid Nasional

TNBT role is to ensure the adequacy and reliability of

electricity supply that are fundamental needs of modern

society. It also provides the link between electricity suppliers

(TNB Generators and IPPs) and electricity consumers.

Besides that, the transmission connects regional systems via

interconnectors to encourage cooperation for mutual benefits.

Fig 2 : Activity chain in TNBT

For Asset Maintenance (AM), their job are :

• To manage the transmission assets to ensure high

availability.

• Conduct effective operation and maintenance of the

transmission network to ensure the reliability of the

equipment.

• To optimize the lifetime performance of network

assets in terms of reliability, availability and costefficiency.

• Implement the Conditioned Based Maintenance

approach.

II. OUTCOME OF INDUSTRIAL TRAINING

A. Substation

This unit is responsible for the commissioning, safe

operation, effective maintenance, and repair of primary

equipment and civil work in substation installed at

transmission facilities in Asset Maintenance Melaka.

There are two types of transmission substation designs

used TNBT which is Air Insulated Substation (AIS) and GasInsulated Substation (GIS). The AIS design consists of air-

insulated equipment installed in outdoor switchyard while the

GIS design utilizes SF6 gas insulated equipment installed

inside the building.

Fig 3 : AIS Fig 4 : GIS

There are three types of voltage rating under AM Melakacustody which is 275/132 kV, 132/33 kV and 132/11 kV. The

AIS is easier to maintain compare than the GIS. Table I

shows the main equipment in substation. The equipment in

the GIS has the same equipment as AIS equipment.TABLE I

MAIN EQUIPMENT IN SUBSTATION

Equipment Description

Transformer Step down voltage from generation

system to much lower level so power can

be transmitted to distribution system

Lighting Arrestor Protect transformer and electrical

equipment from being damaged by

lighting pulse or over-voltage operation

Current

Transformer

Reduces the primary current to much

lower, standardized levels that suitable

for operation of relays

Voltage

Transformer

Reduces the primary voltage to much

lower, standardized levels that suitable

for operation of relaysCircuit Breaker Complete, maintain and interrupt

currents flowing in a circuit under

normal or faulted condition

Busbar Intermediate device that connects a

variety of electrical equipment in

Industrial Training at Asset Maintenance, TNB Transmission Melaka

Mohd Ghazali B. Mohd Nor CE080082

[email protected]

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mailto:[email protected]

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substation

Isolator Switch to open/close circuit without

loads

Capacitor Bank Improve quality of the electrical supply

and the efficient operation of power

system

B. Lines and Cable

This unit is responsible for the commissioning, safe

operation, effective maintenance, and repair overhead lines

and cable. Overhead lines are used to deliver power at high

voltage from generating plants. Transmission lines in the

TNBT system range from 66 kV to 500 kV. There are two

types of lines towers which is self supported (275 kV, 132

kV)and guy supported (< 66 kV).

Underground transmission cable are commonly used in

urban areas where the land constraint to build overhead lines.

There are two types underground cable that used in TNBT

system which is Oil-filled cable and XLPE insulated cable.

Fig 5 : Overhead Line Fig 6 : XLPE insulated cable

In TNBT lines towers, there seven types of self-supported

lattice tower (SSLT) are used. The types of tower are

distinguished by the angle of deviation respectively as shown

in Table II.TABLE II

TYPES OF 132 KV OVERHEAD LINES AND ANGLE OF DEVIATION

Types of Overhead Line Angle of DeviationL - Suspension (Wooden Cross Arms) 0-2

SL – Suspension (Steel Cross Arms) 0-2

S - Section 2-10

M – Medium 10-30

H – Heavy 30-60R – Right 60-90

T – Terminal 0-10 Nowadays in transmission lines conductor, copper has

been largely replaced by aluminium. There are four types of

conductor that been used which is :

• ACSR – Aluminium conductor steel reinforced

• AAC – All-aluminium conductor

•

AAAC – All-aluminium alloy conductor • ACAR – Aluminium conductor alloy-reinforced

C. Protection

Protection system is required to detect abnormal activities.

There three scheme protection that installed at transmission

facilities which is transformer protection, line feeder

protection and busbar protection. All scheme protection used

a protection relay as it main device. This scheme has two

types of protection which is main protection and backup

protection.

Fig 7 : Protection system in TNBT

Transformer protection scheme is focusing on transformer

from fault or any abnormal condition. This scheme protect

HV and LV transformer. If any fault/tripping been detected,

this scheme will operate on its condition. There are several

main relays that installed in the scheme such as overcurrent,

differential, restricted earth fault (REF), standby earth fault

(SBEF) and transformer guards.

Line feeder protection scheme is focusing on distance from

substation to another substation. There four types of distance

protection zones which is :• Zone 1 – 80% long length forward

• Zone 2 – 100% + 20 % long length forward

• Zone 3 – 200% long lengh forward

• Zone 3 Reverse – 20% short length reverse

Busbar protection scheme is focusing on busbar protection

and protection zone. For busbar protection, high impedance

and low impedance scheme been installed. This scheme

mean the protection from the CT ratio. For protection zone,

each zone has been categorized in four different zone which

is :

• Generator zone

• Transformer zone

•

Buses zone• Line zone

In this scheme, the CB is located at overlap region as shows

at fig 8.

Fig 8 : Zone of protection

For backup source for relays, the station battery has been

installed in substation. The battery used nickel cadmium

battery type that’s flows a DC supply.

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Fig 9 : Station Battery

D. Condition Monitoring Unit

CMU is responsible for support maintenance especially

for Mechanical and Electrical (M&E) installations of

substation in term of scanning, measuring and analysis.

Type of test and measurement used are :

• Tangen Delta

• Dissolve Gas Analysis

• Leakage Current Monitoring

• Thermovision• Ultrasound

17.0°C

46.9°C

20

30

40

Fig 10 : Thermovision measuring Fig 11 : Ultrasound measuring

E. Telecontrol

Telecontrol’s unit is responsible to ensure the SCADA

(Supervisory Control and Data Acquisition) ready status isavailable at any substation for the safe operation and reliable

performance. This system monitored

• Status and alarms

• Sequence of events

• Binary Code Decimals

• Analogue inputs

There are two types of SCADA system which is RTU

(Remote Terminal Unit) and SCS (Substation Control

System) as shows in Fig 12 and Fig 13.

Fig 12 : SCS equipment Fig 13 : RTU equipment

R EFERENCES

[1] Abdullah Hj. Abd Rahman, Noor Adnan Abd. Aziz (Ogos 2003), TNBTransmission Electrical Safety Rules First Edition

[2] Asset Maintenance Guidelines for TNB Transmission Division, (Sept2008)

[3] Nor Akmal Mohd Jamail, Siti Amely Jumaat, Roziah Aziz (Julai 2009),Electrical Power System

[4] D. F. Warne (2005), Newnes Electrical Power Engineer’s Handbook, Newnes

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TNBT Seminar Paper

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