Jemena upgrades historic Yarraville Zone Substation

Yarraville substation

In February, the lights went out at Yarraville Zone Substation, north-west Melbourne’s key electricity plant, with a history going back more than 90 years. Next door, the company’s $15 million upgrade was commissioned, with the capacity to power more 15,000 customers.

Jemena has completed its $15 million upgrade of its Yarraville Zone Substation, 8km west of the Melbourne CBD.

In the past decade, peak demand in the 950sq km Jemena Electricity Network – which ranges from Couangalt in the north to Footscray in the south – has increased by 23 per cent to around 320,000 homes and businesses. Once a working-class suburb, Yarraville has experienced rapid gentrification in recent years, largely due to its close proximity to the CBD and major developments including Yarraville Village’s bourgeoning café culture, the restoration of the art deco Sun Theatre and a $738,000 upgrade to the Yarraville Station Plaza transport hub.

Jemena estimates the population will continue to boom in the next 20 years, with around 340,000 people forecast to live and work in the Jemena Electricity Network as early as 2015.

Jemena Electricity Network general manager Richard Twisk said residential, commercial and industrial customers in Yarraville and surrounding areas will directly benefit from the upgrade, which involved installing two new transformers, new switchgear and the construction of a new control building.

“Our upgrade of the Yarraville Zone Substation assets is part of Jemena’s investment in the community,” he said.

“By maintaining and upgrading the company’s distribution network assets and zone substations, we will ensure we continue to provide safe, cost-effective, efficient and reliable supply to our customers at a time of rising peak demand and growth in customer numbers.”

Out with the old: Decommissioning the Yarraville Zone Substation

As the main point of supply to Yarraville and its surrounds, the Yarraville Zone Substation, otherwise known as the Yarraville Terminal Station (YTS), operated at 66/22/6.6kV, supplying more than 5000 customers in the area.

The substation was built in the early 1920s during the electrification of Victoria, making it the oldest station in the Jemena distribution network. The site is historically significant as it is the first terminal station established in Melbourne by the then newly-formed State Electricity Commission (SEC).

The original plant remained active service until 7.10am on February 5, when the site was decommissioned and the transformers fell silent for the first time in more than 90 years.

Network controller Peter Lauk and senior engineer Sandro Bongetti began preparation for the final shut down at 5am, taking great lengths to commemorate the historically significant moment.

“Peter – who had been involved with YTS for more than 30 years – ensured the clock was set to the correct time and then commenced switching. He contacted the control room and requested YTS be shut down locally onsite and not via remote control from Mt Waverley. We agreed to do this as a respectful gesture to recognise the 90 years of service,” Mr Bongetti said.

“The prepared switching sequence was followed by Peter in consultation with the controller over a phone link. The last circuit breaker to be tripped was the 1-3 66kV bus tie at 0710 hours, to enable line workers to cut over the final 66kV line from YTS to the new Yarraville zone substation, which is referred to as YVE.”

“Line crews from Broadmeadows made the final connections by 1pm. The infrastructure still stands in the old YTS and it is presently being upgraded and cut into the new YVE,” Mr Lauk added.

“Prior to this day, Sunshine Cables Group and Broadmeadows Operations systematically, one-at-a-time, transferred each distribution feeder from YTS to YVE. Each feeder cable had to be unearthed, cut and joined to its new position.

“It’s been a long and at times challenging upgrade, with delays in equipment arrival, hot and wet weather and asbestos inherited from past construction. Project construction manager Michael Reilly really deserves acknowledgement for making things happen onsite.”

With part of YTS now heritage listed, including its latticework doors and indoor control panel, the original substation will remain standing.

According to Mr Lauk, the old machine room, which housed the synchronous condensers and the frequency changer, is now being used as a test lab by SP AusNet.

“The old 66kv and 22kv switchyard will slowly be dismantled and environmentally cleared up. No formal decision has been made on what the site will be used for in the future. Some say the old control room will be turned into a conference room. I am sure it will all stay for another generation,” he said.

Historical, technological and architectural significance

YTS was the main receiving station for electricity transmitted from Yallourn Power Station, a complex of six brown coal-fuelled power stations that commenced construction in 1921, to the greater Melbourne area.

In June 1923, a 12,500kW frequency changer installed in the Yarraville Terminal was brought into operation, converting 25-cycle energy from Newport Power Station to 50-cycle energy for the city of Melbourne. In June 1924, with the transmission line completed, the first electricity generated from brown coal reached Melbourne and Yarraville Terminal Station came into full operation.

“Originally designed as a 132kV/22kV/6.6kV terminal station, there were two transformer groups, each consisting of single phase water-cooled units. The 3A and 3B transformers were also water-cooled,” Mr Bongetti said.

“The single-phase transformers were re-wound to 66kV/22kV/6.6kV in the mid-to-late 1950s. By 1993 the single-phase transformers were converted from water-cooled to air-cooled by installing radiators salvaged from Yallourn Power Station. The 3B transformer was also modified in this way and the 3A transformer was no longer required for service.

“In 2006/2007, the last 6.6kV customer relocated their business and the 6.6kV switchyard was later demolished to make way for the new substation.”

The site is historically significant because of its provision of electrical power from the Latrobe Valley brown coal deposits. The creation of the Latrobe Valley brown coal electricity generation scheme and the SEC was a major step in the development of Victoria, having ramifications for industry, employment and quality of life.

Architecturally the Machine Hall is noteworthy as it’s one of the earliest remaining SEC buildings in the state. Its functional, yet monumental and classically-inspired form, is typical of many large-scale government works and initiatives in Victoria from this time.

“The Control Building, comprising Machine Hall floors, were laid with ceramic tiles, riveted structures, riveted transformer tanks, polished brass fittings on the rotating machines and polished floors in the control room,” Mr Bongetti said.

The three storeys of the Machine Hall, which were constructed in 1921-22, remain relatively intact and visitors to the site can still view the steel reinforced concrete structure with regular fenestration, a prominent hipped roof and overhanging eaves – typical design features of the day. The ground floor comprises the Machine Room, which also retains some original tiled floor areas, high voltage testing equipment and a crane gantry.

The site at Yarraville also included workshops specialising in switchgear, line gear and switchboards before WWII, a spare parts store and laboratories for electrical research.

“Lots of unique pieces of plant, equipment and auxiliaries come to mind when thinking about the old Machine Room. For example, the frequency changer converted the 50Hz supply to 25Hz for the Victorian Railways, before being decommissioned in the mid-1980s when more modern technology allowed it to be replaced with electronic conversion at the railway’s end,” Mr Bongetti said.

“The two synchronous condensers and the frequency condenser had water-cooled white metal bearings, which required an extensive array of reticulated water systems. It was time-consuming to maintain as it had to be regularly dismantled and recoated internally with a bitumous paint to stop corrosion.

“This was done by pouring in the bitumen and pushing and pulling a rag through the pipe lengths – similar to how rifle barrels were cleaned. It was messy and all the fitters hated the task as they became just as tarred as the pipes.

“As you can imagine, the apprentices copped the worst part. A huge spray pond was used to cool the water and then circulated. The regular cleaning of the pond was also another dreaded task for the fitters as lots of sludge and muck was involved – except in summer when there was a flood of volunteers!

“The design of the old plant is unique, because it was built with what was available at the time,” Mr Lauk added.

“For example, two transformers converted 66kv to 22kv plus had 6.6kv tapped in as well. This 6.6kv supply was dedicated to ICI Chemicals, a very important and political company in its day, when operating in Yarraville.

“What’s more, 22kv was the needed voltage and to achieve this with the available materials, one transformer had to convert 66kv to 11kv and feed another transformer at 11kv and convert it to the required 22kv.”

environmental and Reliability issues

With the substation’s No.1 and No.2 transformers installed in 1922, it’s not surprising significant reliability and environmental issues presented themselves throughout the years.

At a major site evaluation in 2011 it was determined through condition testing and fault history that all three transformers were at the end of their life. Other pieces of primary equipment, including circuit breakers, were of 1950s vintage, which not only caused high maintenance costs, but also led to concern about equipment failure and poor reliability.

“The transformers developed internal faults, which required investigation, testing and repairs. Switchgear failures also occurred due to vermin contacting HV connections. The control and protection cables, which were installed in underground pits and the interconnecting conduits also collapsed over the years, which allowed water to enter the pits. This caused earth faults on the 240Vdc battery every time it rained,” Mr Bongetti said.

“One early morning about 15 years ago, interruption to
50 per cent of customer supplies occurred due to a cat and dog. A bull terrier chased a cat into the switchyard, up the stairs, onto a balcony, along an overhead gantry supporting a 22kV bus. The cat walked along the bus support structure followed closely by the dog. They were both electrocuted.”

In with the new: The YVE rebuild project

Due to the age of the YTS site and the growing supply demands of the region, a new substation was built directly in front of YTS to provide improved supply quality to the local area.

Phase one of the two-step rebuild project was spread across the 2011/12 and 2013/14 financial years. Costing $14.4 million, phase one included retiring No.1, No.2 and No.3B transformers, and installing two new transformers. The project team also replaced ageing switchgear.

Phase two, which is set for the 2016-2020 regulatory control period, includes the addition of a third transformer, feeders and power factor correction capacitor banks to meet projected load growth.

With today’s technology, YVE can provide twice the capacity of the former substation, while only taking up one sixth of the size of YTS.

“Technology has condensed the physical size of zone substations. Circuit breakers are internally insulated by gas, compared to the medium of oil. Size is thus reduced by
75 per cent,” Mr Lauk said.

“Switchgear is built in modular form and is assembled compartment by compartment. All gear is housed internally in a switch house, again reducing space required by
75 per cent. Station protection is achieved by protection relays that provide multiple functions – one relay nowadays can do the job of five in the old days.

“What’s more, communication from the new era YVE is via fibre optic. Monitoring of the station is very visible. Any event that happens on the station is relayed to system control. Nothing can be hidden, all can be seen.

“YVE innovatively used existing infrastructure to provide a zone substation in a fast growing commercial and industrial centre that can be readily expanded in the future to meet load growth.”

Differences in design

Outdoor 22kV switchgear replaced by new indoor arc fault contained 22kV switchgear, which greatly improves supply reliability and safety of personnel.

Water-cooled single-phase transformers (30MVA) fitted with an OFF Load Tap Changer have been replaced with modern designed, efficient three-phase transformers, which are oil/air cooled, plus an in tank On Load Tap Changer for voltage control.

Transfer track and trolley to remove old single-phase transformers were made redundant as mobile lifting equipment and superior electrical designs were developed throughout the years.

Modern HV plant and electrical designs provides for a compact zone substation layout.

Fire risk due to oil-filled switchgear has been eliminated as modern technology utilises gas and vacuum circuit breakers, and reduces the cost of maintenance.

Cable pits were interconnected with conduits made from paper coated in bitumen. Cable pits are still used with PVC interconnecting conduits.