It is a four 150MVA (220/66kV) and two 165MVA (220/22kV) transformer station that feeds key loads within the Melbourne CBD and surrounding suburbs.
The station has operated for more than 40 years in its current form and has now reached the end of its economic life and therefore requires replacement of its aging assets to improve security of supply.
The upgrade involves replacing most of the current external electrical switchgear with new more compact switchgear, housed in three new buildings.
The terminal station must remain operational throughout construction so all upgrade works are taking place in a series of separate stages. As a result the construction program is a complex brownfield undertaking and will take approximately five years to complete.
Scope of works
Zinfra was engaged in 2015 to deliver the initial 66kV and 220kV cutover, demolition and construction works and has since secured further works as part of work package 9 (WP9) as a result of the team’s performance in achieving key performance milestones.
Works involve the demolition of old electrical infrastructure, installation of new primary connections, secondary installation, termination and testing and commissioning.
In high level terms the complete RTS rebuild involves:
Replacement of all 220kV assets other than some structures and the 220/22kV transformers
Most of the 220kV switchgear will be replaced with indoor gas insulated switchgear (GIS), except the transformer connections
Replacement of four 220/66kV 150MV transformers with three 220/66kV 225MVA transformers
Replacement of all 66kV primary switchgear with indoor gas insulated switchgear (GIS)
Replacement of all 22kV primary switchgear with a three bus indoor switchboard
Installation of a 220/22kV 75MVA transformer (L3) for construction transitional temporary supply
New or modified protection associated with the above.
Working within an operational environment
As RTS is a critical link in the supply chain to the Melbourne CBD and inner suburbs, it must remain fully operational during the project works, with a reliable supply of electricity maintained at all times.
As a result, all outages are required to be carried out in off-peak periods, with cutovers to the new switchgear limited to periods of low load, usually throughout spring and autumn. However, ensuring supply remains reliable requires tricky strategic sequencing.
"Because the project is so huge, AusNet Services designed it in 12 distinct steps to keep the power on. The sequencing means crews work only in certain areas at certain times. A big challenge is working around the live equipment all the time which requires a lot of permits and, therefore, costs more. The brownfield nature, keeping power coming through it with redundancy and the criticality of the site, creates a complex project".
Installation of first of its kind GIS model
The GIS is among the largest and most technologically advanced switchgear technologies being used in Australia. Specifically, the 220kV GIS model is the first of its kind to be installed in the country at both RTS and Brunswick Terminal Station. The indoor GIS is designed to provide a more stable electricity supply with fewer exposed live components, improving safety. There are added benefits of the GIS compared to the AIS, including it’s compact size (AIS requires larger spacing between phases), minimal maintenance, long life span and greater functionality.
Zinfra brings proven experience and an excellent safety track record in brownfield environments to the RTS project. Fortnightly site walks are conducted by AusNet Services, as well as Zinfra’s internal inspections and audits. Zinfra’s RTS project is currently running on time and to budget and has zero LTIs.