lesliechai@sarawakenergy.com.my

The Sarawak-West Kalimantan 275kV Interconnection

Hot Martua

Bakara

PT PLN

(Persero)

Indonesia

Sahala Turnip

PT PLN

(Persero)

Indonesia

Leslie K.P. Chai

Sarawak

Energy Berhad

Malaysia

T.H. Lo

Sarawak

Energy Berhad

Malaysia

J.H. Kueh

Sarawak

Energy Berhad

Malaysia

SUMMARY

Sarawak-West Kalimantan 275kV Transmission Line Interconnection Project is an integral

part of the efforts by ASEAN utilities to interconnect their electricity grids in the region. It is

the first major interconnection project in the island of Borneo. This paper outlines the

motivation behind this project, evaluation of the design, project specifications,

implementation and provide updates of the current status. The project is expected to be

operational by the end of 2015.

KEYWORDS

Sarawak-West Kalimantan Interconnection, ASEAN Utilities, AC Transmission.

AORC-CIGRÉ CIGRÉ 2015, Malaysia 21, rue d’Artois, F-75008 PARIS http: //www.cigre.org

AORC-CIGRÉ Technical Meeting

Kota Kinabalu, Sabah, 16th – 21st September 2015

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1. INTRODUCTION

The Sarawak-West Kalimantan interconnection is a cross-border High Voltage Alternating

Current (HVAC) connection between the power systems of Sarawak Energy Berhad (SEB)

and PT Perusahaan Listik Negara (PERSERO), located on the west side of Borneo Island (see

Fig. 1).

This project is part of the Association of South East Asian Nations (ASEAN) Interconnection

Master Plan (AIM) to establish an interconnected grid among ASEAN countries for system

security, flexibility and reliability. Besides these operational benefits, the project can also

generate significant international and geo-political interests in the context of regional

cooperation [1]. This could provide opportunities to facilitate economic collaboration and

technical protocols in aid of other future conceptually planned interconnections within the

ASEAN region.

Intrinsically, the interconnection is the pioneer project linking two power utilities in the island

of Borneo with power transfer of up to 230MW to PLN West Kalimantan from the Sarawak

Grid. Such power trading opportunities empower PLN West Kalimantan to plan for its

generation development using economical resources whereby avoid running existing

expensive diesel and fuel oil generation plants which over the time could be in the position to

supply back to Sarawak [2].

In this paper, a comprehensive background information and motivation drivers behind the

project will first be discussed followed by evaluation of the design parameters, technical

specifications and basic scopes of the interconnection systems. The paper then gives updates

on the project implementation progress, current status and expected conclusion of this project.

Fig. 1: Locality of the interconnection

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2. MOTIVATION / BACKGROUND FOR SARAWAK-WEST KALIMANTAN

INTERCONNECTION PROJECT

ASEAN Perspective – Developing an Integrated Trans-national Power System Network

The Heads of ASEAN Power Utilities/Authorities (HAPUA) was founded in 1981 as an

association of national electricity utilities. Since its formation, HAPUA has been striving to

link the power systems of ASEAN countries as a means toward mutual enhancement of

electric supply adequacy, economic cooperation and system security with optimization of the

development of electricity infrastructures and sharing of energy resources in the region.

Prior to the above, several proposed power system interconnection projects in the past on a

bilateral power trading basis were then amalgamated into a framework of an ASEAN Power

Grid (APG) to become a long term plan and vision which was recognized at the Second

ASEAN Informal Summit in the year 1997. HAPUA was then officially requested to establish

the APG prior to the follow up 17th ASEAN Ministers on Energy Meeting (AMEM) in the

year 1999 [1]. Consequently, it had led to the initiation of the ASEAN Interconnection Master

Plan (AIMS) studies in [3] and [4]. The studies proposed many interconnection projects

between power systems in the region. The Sarawak-West Kalimantan HVAC interconnection

is an essential component upon the realization of the ASEAN Power Grid.

Facilitating PLN West Kalimantan’s Generation Plan

The existing generation in PLN West Kalimantan consists mainly of small sized thermal

generators driven primarily using fossil fuel oil. A few larger units of coal fired generators are

also under construction. Despite the recent fall in oil prices, this generation structure

continues to incur high operational cost on PLN West Kalimantan and may create extensive

constraints to the system stability due to the relatively small sized generators connected to its

network.

The interconnection enables PLN West Kalimantan to develop its generation expansion plan

with substantial coal powered generation from local supplies to meet local demand and

conceivably for export in the longer term. According to [6], the generation expansions plan in

West Kalimantan comprises of 1,130MW coal-fired power plants, 200MW of gas

turbine/combined cycle and 113MW of hydro power which will be built over the next ten

years.

The interconnection link can supplement generation at West Kalimantan by providing

adequate support to its load demand growth and bring beneficial support in terms of system

stability and reliability. The interconnector also enhances the security of supply for both

power systems by allowing the sharing of capacity and spinning reserves which provides

flexibility in grid operations.

On 5th September 2012, PLN and SEB come to a mutual agreement with the official signing

of the “Power Exchange Agreement between Syarikat SESCO Berhad and PT Perusahaan

Listik Negara (PERSERO)” or PEA.

The PEA is designed to facilitate power exchange between the two power systems with

designated review periods to cater for changes in the development of both networks.

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During the initial phase of the PEA, PLN will be importing power from SEB with the

quantum of 50MW at base demand and 230MW at peak demand. It is believed that the

interconnector can serve as a catalyst for achieving the APG vision by encouraging other

inter-Borneo links while spurring the development of integrated trans-national connected

power systems.

3. TECHNICAL SPECIFICATIONS AND DESIGN PARAMETERS OF THE

PROJECT

Technical Specifications of the Interconnector’s Transmission Lines

The Sarawak-West Kalimantan interconnection is a HVAC link connecting two systems at the

Mambong 275kV substation in Sarawak to Bengkayang 275kV substation in West

Kalimantan through a double circuit 275kV transmission line at a system frequency of 50Hz.

This project required the extension of two feeder bays at the existing 275kV Mambong

Substation in Kuching. From there a new 275kV transmission line is being constructed to

connect to a new 275/150kV Bengkayang Substation in West Kalimantan. This cross border

transmission line has a total length of 128.2km of which 35.57% is in Sarawak and the

remaining 64.43% lies in West Kalimantan [5] (See Fig. 2). The tower design is a typical

design similar to the existing design used in the SEB power system (See Fig. 3). While the

basic line parameters are comparable between the two power systems, the differences are

tabulated in Table 1 below. Both Table 1 and Fig. 3 were taken from the Planning and

Development System Study Final Report in [5].

Table 1: Comparison on basic line design practices between PLN and Sarawak Energy

Berhad

Description PLN SEB

Line Conductor

Conductor type/name ACSR/AS Zebra ACSR Drake

No. and diameter of Al wire 54/3.18 26/4.44

No. and diameter of St wire 7/3.18 7/3.45

Overall diameter 28.62 mm 28.11 mm

Cross-section 428.9/55.6 mm² 402/65 mm²

Resistance (DC at 20°C) 0.065 Ω/km 0.072 Ω/km

Breaking load 137.8 kN 145 kN

Weight 1,621 kg/km 1,680 kg/km

Ground/Earth Wire

Ground wire type AS 95 ACSR Skunk

No. and diameter of Al wire – 12/2.6

No. and diameter of St wire 19/2.5 7/2.6

Overall diameter 12.5 mm 12.95 mm

Cross-section 93.27 mm² 63/37 mm²

Resistance (DC at 20°C) 0.925 Ω/km 0.567 Ω/km

Breaking load 121.39 kN 53 kN

Weight 626 kg/km 490 kg/km

Tower Design Parameters

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Description PLN SEB

Tower height 50.4 m 35 to 37 m

Clearance open country 10.5 m 7.5 m

Clearance over plantations 7 m 4 m

Clearance to highway, roads 11 m 9 m

Clearance to other lines 5 m 4 m

Basic span 400 m 350 m

Insulators Cap and pin Cap and pin

Communication link OPGW OPGW

Surge arresters Class 3 Class 3

Cross arm – Cross arm >7.4m >6.8m

Cross arm – tower body ~6.9m ~6m

Conductor to ground

Clearance ~15m ~10m

Right of way 15m on each side of tower 20m on each side of tower

Moreover, SEB also adopted differential insulation for its transmission line where circuit 1 is

low and circuit 2 is high as follows:-

i) Circuit 1 has 18 numbers of insulation discs with Basic Insulation Level (BIL) of

approximately 1200kV;

ii) Circuit 2 has 20 numbers of insulation discs with Basic Insulation Level (BIL) of

approximately 1600kV.

As PLN does not have such practice, the numbers of insulation discs remain at 18 numbers

for both circuits.

Fig. 2: The Sarawak-West Kalimantan Interconnection Plan

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Fig. 3: Typical 275kV lattice tower design used in existing SEB power systems

Technical Specification of the Interconnector’s Substations

The basic technical specifications and design parameters of the two interconnected

substations in SEB and PLN system are summarized and tabulated in Table 2. They are

extracted from [5].

Table 2: Basic scope and design of Mambong and Bengyakang 275kV substations

Basic Substation Design Parameters Mambong

Substation

Bengkayang

Substation

1. Number of bays required 2 (extension) 2

2. Bay type Line Line

3. Switchgear type Outdoor

Outdoor (1½

circuit-breaker

scheme)

4. Environment Heavy Pollution Heavy Pollution

5. Busbar configuration Double Double

6. Busbar rating, A 2000 1600

7. Circuit breaker rating, A 2500 2500*

8. Circuit breaker short-circuit rating, kA 25 (3 sec.) 25 (3 sec.)

9. Busbar short-circuit rating, kA 25 (3 sec.) 25 (3 sec.)

10.Maximum voltage for equipment, kV 300 300

11.Short-duration power frequency withstand, kV 460 460

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Basic Substation Design Parameters Mambong

Substation

Bengkayang

Substation

12.Basic SIL/LIL, kV 850/1050 850/1050

13.Minimum safety clearance, mm 4800 4800

14.Line reactor rating 3x5MVAr 3x5MVAr

15.Teaser reactor rating TBA –

In addition to Table 2, there is a plan to install 275kV shunt capacitor banks at Mambong

substation with capacity of 2×40MVAR and 2×80MVAR while another 3×20MVAR capacity

of shunt capacitor banks will being installed at 132kV.

On the PLN West Kalimantan side, shunt capacitor banks are planned to be installed at

various 150kV substations including Singkawang 150kV substation in the year 2016 and Sei

Raya 150kV substation in the year 2017 each with a capacity of 1×25MVAR to be switched

on during maximum load [5].

As for the interconnection protection and control scheme, it was mutually agreed for both

PLN West Kalimantan and SEB to employ one current differential and one distance

protection for each circuit as below:-

i) Main 1: Current Differential (with backup of distance protection);

ii) Main 2: Distance Protection.

4. CURRENT PROJECT STATUS AND UPDATES

Current Project Status

The interconnector is scheduled to be operational by the end of 2015 supplying 50MW of

power to PLN West Kalimantan from SEB initially.

In due course, SEB will be exporting 230MW power to PLN West Kalimantan during peak,

upon majority completion of SEB’s 500kV backbone transmission line projects sometime in

2016. The SEB 500kV transmission line backbone is a high voltage transmission system

extending over 500 kilometers from Similajau in Bintulu to Tondong in Kuching. It is a

system reinforcement project supporting the future development of its generation system and

to provide adequate security of supply to cater for its electricity demand growth. Due to the

rapid growth in demand and consumption in Sarawak, this added transmission capacity will

further strengthen the network especially towards Kuching.

Table 3 shows the work progress for Mambong substation extension and transmission line

works in Sarawak whereas Table 4 shows the work progress for Bengkayang substation and

transmission line works in PLN West Kalimantan.

Table 3: Sarawak-West Kalimantan Interconnector substation and line progress in Sarawak

updated as at June 2015

Sarawak Completion Expected Completion

Mambong 275/132kV Substation Extension 78%* Quarter 3, 2015

Transmission Line 98% Quarter 3, 2015 * Progress reported includes portions not specifically related to this Interconnection

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Table 4: Sarawak-West Kalimantan Interconnector substation and line progress in PLN West

Kalimantan updated as at May 2015

PLN West Kalimantan Completion Expected Completion

Bengkayang 275/150kV Substation 85.46% July 2015

Transmission Line 89.33% July 2015

Planning and Operational Studies

Two joint system studies are currently being undertaken by SEB and PLN West Kalimantan

to analyze the impact, stability and operational aspects of the interconnection link.

These studies evaluate the steady state performance, transient responses and frequency

response of both power systems after the interconnector has been commissioned.

5. CONCLUSION

This paper outlines the motivation behind this project, evaluation of the design, project

specifications, implementation and provide updates of the current status.

The interconnection is the pioneer project linking two power utilities in the island of Borneo

with power transfer of up to 230MW to PLN West Kalimantan from the Sarawak Grid during

the initial phase. With the link expected to be operational by end of 2015, both SEB and PLN

West Kalimantan are looking forward towards a mutually beneficial interconnection.

Technically the interconnection link will improve the security of supply for both SEB and

PLN West Kalimantan through sharing of capacity and spinning reserves especially in the

long term. The interconnection will also improve operational flexibility where one system can

support the other in case of emergencies such as generation outages.

Immediately, the interconnection will help PLN West Kalimantan to reduce the running of

expensive fossil fuel generation such as diesel plants, leading to reduced cost of supply. The

power export to West Kalimantan also enables PLN to save the capital investment cost for

additional new generation capacity in the immediate term to allow it to concentrate on least

cost medium to long term solutions. On the other hand, Sarawak can benefit from a

reasonable revenue income from the power export to PLN West Kalimantan while helping to

ensure the stability of the interconnected power grid.

Moreover, this project is part of the ASEAN Interconnection Master Plan (AIM) to establish

an interconnected grid among ASEAN countries for system security, flexibility and

reliability.

It is hoped that besides operational benefits, the project can serve as a catalyst for future

interconnections within the ASEAN region.

6. BIBLIOGRAPHY

[1] ASEAN Power Grid Project A Working Group of HAPUA, "ASEAN Interconnection

Master Plan Study I," 2003.

[2] L. P. Tan, "Planning and Development System Study for The Sarawak - West Kalimantan

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Interconnection Project," Transmission System Planning, Sarawak Energy Berhad,

Kuching, 2013.

[3] D. H. A. Lee, S. K. Liu and L. P. Tan, "Planning Considerations for the Proposed East-

West Malaysia HVDC Transmission Link," EPRI 2013 HVDC & FACT Conference, pp.

1-2, 28-29 August 2013.

[4] J. Irving, Y. Inoue and K. Prakoso, "An Evaluation of the Prospects for Interconnections

Among the Borneo and Mindanao Power Systems," Asian Development Bank, 2014.

[5] ASEAN Power Grid Project A Working Group of HAPUA, "ASEAN Interconnection

Master Plan Study II," 2010.

[6] PT PLN (Persero), "RUPTL 2015 - 2024 (Ten Year PLN System Planning)".

7. ACKNOWLEDGEMENTS

The SEB authors would like to acknowledge the contribution of various people, instrumental

in guiding this project forward specifically, Mr. Nick James Arnett Wright, Mr. Danice

Endawie Ita and Dr. Denis Lee Hau Aik.

The PLN authors would like to acknowledge the contribution of various people, instrumental

in guiding this project forward specifically, Mr. Murtaqi Syamsudin, Mr. Moh. Iqbal Nur and

Mr. Budi Chaerudin.