Transforming transmission development

Transforming transmission development

Hubert Schenner

VA Tech Elin Transformatoren GmbH

Austria

Strong economic growth in the mid-1990s led the Malaysian government to embark on major infrastructure development to fuel its `tiger` economy. This included the construction of a 500 kV transmission network and associated substations across Peninsula Malaysia. Now almost complete, the system waits for the economy to kick-start once more.

In the mid-1990s, Malaysia was recording annual average economic growth rates of more than eight per cent. The growth of this `tiger` economy continued for a period of several years until the region`s current economic downturn began. This rapid economic development needed an appropriate infrastructure in order to support it, including a reliable electrical power generation and supply system.

In addition to various power plant projects designed to meet the growing energy demand, rising at the time at 12 to 15 per cent annually, Tenaga Nasional Berhad (TNB), the national Malaysian utility, realised the importance of a strong transmission grid system to support the new capacity. As a result, it planned the installation of a 500 kV Extra High Voltage (EHV) transmission system for Peninsula Malaysia.

A project team was therefore formed comprising experts from TNB as well as from Ranhill and Black & Veatch International. This team was responsible for the engineering of the entire substation and transmission line layout as well as for selection of the appropriate equipment, the issuance of the tender specifications and the supervision of the construction progress.

Reducing losses

The installation of a new superimposed 500 kV grid is therefore underway on Peninsula Malaysia in three main phases to strengthen the national grid. The first phase of the project contains two substations completely equipped with 500 kV accessories, another six substations with 275 kV equipment (with the capacity for future upgrades to 500 kV operation) and 500 kV overhead lines between all of these substations.

The main purpose of the project is to reduce transmission losses as well as to improve the stability of the existing national grid which currently consists of 66 kV, 132 kV and 275 kV networks. The construction of the planned EHV system is being carried out in three steps, the first two of which have already been completed.

Under the first stage of the project, Phase 1, two 500 kV substations have been constructed on the western coast at Kapar and Bukit Tarek, close to the country`s capital, Kuala Lumpur. Another three substations – at Ayer Tawar, Junjong and Gurun – have been prepared for future upgrading to 500 kV operation.

At the same time another 500 kV line has been installed in the south of Peninsula Malaysia under Phase 1A. This is to originate from Pasir Gudang (just north of Singapore) and extend over a distance of approximately 140 km to Yong Peng via Bukit Batu. Three substations have also been prepared for future upgrading to 500 kV operation along this route.

The order for the turnkey installation of this part of the project (Phases 1 and 1A) was awarded to a Malaysian consortium formed by Malaysian Resources Corporation Berhad and Permodalan Nasional Berhad (MRCB-PNB). VA Tech Elin was responsible for the supply of the 500/275 kV single phase autotransformers with a bank capacity of 750 MVA. The work undertaken for Phases 1 and 1A is shown in Figure 2.

For the time being, all the line sections connecting the substations in Phases 1 and 1A are being operated at 275 kV, except between Kapar and Bukit Tarek. The third phase (Phase 2) of the project, scheduled to begin in the near future, will include upgrading of the Phase 1 and 1A substations with 500 kV equipment and also the installation of a transmission line connecting the northern and southern parts of the EHV grid.

Additional substations will be installed on the eastern coast and in the central part of Peninsula Malaysia to facilitate the development of a 500 kV closed-circuit network by the year 2010-2015.

Fierce competition

In the summer of 1994, international tenders were called for the equipment and installation work of the first stage of the project by MRCB-PNB. VA Tech Elin Transformatoren GmbH together with Perbadanan Kemajuan Negeri Perak (PKNP), its local partner, submitted offers for the 500 kV transformers and related equipment.

The evaluation of the bids as well as extensive clarification of technical details lasted until the summer of 1995. Final negotiations took place and were concluded in late October 1995.

The order for these first 500 kV transformers to be installed in Malaysia and thus the entry into the EHV transmission system market was competed for fiercely. Decisive factors in placing the order with VA Tech Elin and PKNP, besides the price and the offered performance data, were the references of previous delivered 500 kV and 765 kV transformers and their excellent performance over decades of operation.

VA Tech Elin has extensive experience of similar equipment in the range of 500 kV and 765 kV from previous deliveries worldwide, and especially in the south east Asian region.

For instance, in 1982/83, a total of 22 units (transformers and shunt reactors) were supplied to Indonesia for the installation of the first 500 kV network in Asia outside of Japan. The majority of 500 kV substation transformers in Indonesia have been supplied by VA Tech Elin Transformatoren.

In addition, the first 500 kV transformers installed and in operation in the United States were supplied by VA Tech Elin Transformatoren in 1965. The delivery of a 765 kV transformer to the USA in 1977 marked the entry of VA Tech Elin Transformatoren into the US market for maximum operational voltage levels and was followed by a number of similar transformer units as well as 765 kV shunt reactors during the last two decades.

Other 500 kV transformers and shunt reactors supplied by VA Tech Elin Transformatoren have been in operation for several years in China, Pakistan and Argentina.

The contract awarded to the VA Tech Elin Transformatoren – PKNP partnership included the supply and installation of 500 kV transformers with a total output of 3000 MVA as well as 33 kV earthing transformers and earthing resistors manufactured in Malaysia. The 500 kV transformers were designed and manufactured in Weiz, Austria.

VA Tech Elin`s scope of supply for the project included 12 single-phase 50 Hz 500/275/33 kV autotransformers, twelve 275 kV and twelve 33 kV metal oxide surge arresters, four earthing transformers with a nominal voltage of 33/0.415 kV and two 33 kV neutral earthing resistors. Also covered in the terms of the contract were tertiary and neutral busbars for the power transformers including steel structures and station post insulators, 33 kV cable connection between earthing transformers and neutral earthing resistors, and automatic voltage regulation and parallel operation device for power transformers

VA Tech`s consortium partner, PKNP, was responsible for the local sourcing, transportation in Malaysia and installation of all the equipment.

Design review

After the official contract signing in November 1995, experts from TNB and MRCB-PNB were informed of the design details during the design review. This took place as early as February 1996.

The design review discussions included the presentation of calculations with respect to the dielectric stresses, the thermal conditions, noise and vibration conditions, the mechanical strength for short circuit conditions and the load and no-load loss values.

Also discussed were: a description of geometrical arrangement of core, windings and connecting leads to the on-load tap changer and to the bushings; the support of active parts within the transformer tank with respect to transportation forces; a description of the on-load tap changer, bushings and cooling equipment; the transformer tank design with arrangement of access and assembly holes; and the protection system (e.g. bushing current transformers, Buchholz relay, sudden pressure relay, pressure relief device, oil level indicator, oil and winding temperature indicators, Hydran sensor).

Topics discussed in particular at the review included:

ࢀ¢ the benefits of used indirect regulation of 500 kV winding with regulation winding arranged near neutral point, thus minimizing voltage stress for the on-load tap changer

ࢀ¢ measures to prevent overheating due to leakage flux

ࢀ¢ the concept of automatic voltage regulation and parallel operation device designed already for future extension of the substations with additional transformers.

In addition to the information submitted during the bidding stage, the quality management system of VA Tech Elin Transformatoren, which is organized according to the ISO 9001 standards and certified by an international certification body, was explained in detail.

After five months, and thus within a timescale of only eight months altogether, the first three single-phase units were subjected to extensive type and routine tests at the VA Tech Elin Transformatoren test laboratory in Weiz, Austria, in July 1996. In addition to the tests on the transformers, type tests were performed on one tap changer in Rheinhausen, Germany.

The results of these tests showed the equipment`s compliance with all the warranted specification data to the satisfaction of the customer. At intervals of six weeks, the remaining units (banks two to four) were subjected to factory tests thus proving operational suitability.

Following the factory tests, the transformers were prepared for the long journey to Malaysia, a distance of around 17 000 km, by removing the bushings, cooling devices and all other attachments which can impede transportation.

After rail transport from Weiz to Linz in Austria, the equipment was shipped to the port of Antwerp via inland waterways – the rivers Danube, Main and Rhine. From Antwerp, the transformers were transported by ocean vessels in a five-week voyage to Port Klang, Malaysia`s main harbour, where the goods were loaded onto 12-axle heavy road vehicles.

Although the transformers were manufactured in single-phase design, additional measures had to be taken to facilitate delivery to the Bukit Tarek substation because of general transport restrictions in Malaysia.

For example, for the heavy transformer parts, weighing approximately 160 t each including the vehicle, a temporary access road had to be constructed from the nearby highway to the station located at the edge of the tropical rain forest.

Despite these difficult conditions, the local Malaysian carrier was able to transport all units within the scheduled time frame.

Installation

Immediately following the completion of the foundations, the installation of the first transformers started at Kapar substation in October 1996.

Instructed by an installation expert from the VA Tech Elin Transformatoren factory at Weiz, a number of local technicians worked with equipment unfamiliar to them to install the equipment. Nevertheless, after a short training phase, good progress was made and the installation was completed almost on schedule in spite of adverse environmental conditions (monsoon rain and temperatures of up to 45à‚°C in the shade, for example).

After the commissioning tests carried out in the presence of representatives of MRCB-PNB and TNB in second and third quarter of 1997, the transformers were handed over to the customer.

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Figure 1. Malaysia embarked on major infrastructure investment as its economy boomed in the mid-1990s

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Figure 2. The 500 kV transmission system development (phases 1 & 1A)

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