Renewables Flow Via Australia Interconnector

Australia’s electricity grid is undergoing the biggest change in this lifetime as coal-fired generation retires earlier than anticipated and the shift to renewables gathers increasing speed. At the heart of the transition is Transgrid, which operates and manages the high-voltage electricity transmission network in the eastern Australian states of New South Wales (NSW) and the Australian Capital Territory (ACT), connecting generators, distributors and major end users.

The Transgrid network comprises over 13,000 km (8078 miles) of high-voltage lines and 113 substations in NSW and the ACT, with connections to Victoria and Queensland.

Transgrid is working to deliver Australia’s energy transition to a renewables-based grid as efficiently as possible, without sacrificing grid security and reliability. A key part of that goal is using the existing network as effectively as possible by embracing innovations that can help to unlock additional capacity. In 2020, Transgrid signed a contract with Smart Wires Inc. for the delivery of modular power flow control technology, SmartValve, as part of the Victoria-NSW Interconnector (VNI) project. The A$45million upgrade of the main link between NSW and Victoria has unlocked 170 MW of additional energy.

Project Need

The integrated system plan prepared by the Australian energy market operator (AEMO), which operates Australia’s national electricity market, identified a need to increase the transfer capability between Victoria and NSW. Transfer between the two states was restricted by thermal, voltage stability and transient stability limitations.
Over time, these limitations on the interconnector would have led to reduced access to lower-cost generation sources in the southern states, resulting in an increased economic cost of generating electricity across the Australia electricity market and growing the requirement for new generation investment to maintain adequate

AEMO and Transgrid jointly initiated a regulatory investment test for transmission (RIT-T) to assess network and non-network options to increase transfer capacity between Victoria and NSW. In line with the RIT-T process, AEMO and Transgrid published a project specification consultation report (PSCR), which identified the need for and benefit of additional export capability from Victoria to NSW. The PSCR was followed by the project assessment draft report (PADR), which identified and sought feedback on the proposed preferred option that would deliver the highest net economic benefits to stakeholders (referred to as net market benefits).

All consultation submissions to the PADR were evaluated and considered before publication of the final report, the project assessment conclusions report (PACR). The preferred option was to implement the following by 2023:

• Install a second 500/330-kV transformer at the South Morang terminal station.
• Re-tension the 330-kV South Morang-Dederang transmission lines and associated works, including replacement of series capacitors, to allow operation at thermal rating.
• Install modular power flow controllers on the 330-kV Upper Tumut-Canberra and Upper Tumut-Yass lines to balance power flows and increase transfer capability.

The RIT-T analysis determined this preferred option would generate sufficient market benefits to recover the project cost within a short time frame and, therefore, was not subject to future uncertainties. The RIT-T recommended the optimal technology option for Transgrid to proceed with; however, the purchase of equipment remained subject to national and corporate procurement rules.

The project was also recognized as a priority by the NSW state government in its transmission infrastructure strategy.

Project Scope

The VNI upgrade project involved the installation of 15 SmartValve units at 330 kV across two sites, the Stockdill substation in the ACT and Yass substation in NSW, in 2022. Nine SmartValve units were installed at the Stockdill substation to unlock 120 MW of additional energy, while six units at the Yass substation provided another 50 MW.

In Australia, renewable energy often is produced in remote regions, which can cause bottlenecks on grid infrastructure.
The modular power flow controllers enable real-time control of electricity flows along power lines. If the SmartValve system detects areas of congestion on the network, it can automatically redirect flows to less congested lines with spare capacity.

Transgrid was the first large-scale user of SmartValve technology in Australia. It is already used extensively in the UK, US and South America to help unlock renewable energy flows and achieve net-zero targets.

Transgrid’s then Head of Infrastructure Development Jeremy Roberts said: “By using the SmartValve technology, we were able to upgrade substations while using existing transmission line infrastructure. It meant no new lines needed to be built, so the extra energy we needed could be unlocked with minimal environmental and community impacts associated with building or upgrading existing lines.

“Clever technology like this helps us to meet the challenge of supporting a decarbonised future, while ensuring a consistent, reliable supply of lower-cost energy for customers,” he added.

Following the preliminary investigations, design and approval processes, construction got underway in early 2021 and the project was delivered in November 2022.

Project Benefits

The VNI project is expected to deliver significant benefits for consumers:

• Increased export capability from Victoria to NSW, with 170 MW capacity unlocked on the interconnector to enable greater access to renewable energy generation across the states
• Consumer savings of AUD$268 million (a net present economic benefit) from a reduction in dispatch costs through more efficient dispatch of generation in the two states as well as a reduction in capital costs associated with new generation build in NSW
• Accelerated development of renewable generation by quickly and cost efficiently unlocking more capacity on the existing grid
• Improved security of supply that supports more reliable supply of electricity to customers, including during periods of peak demand
• Boost to local employment during project implementation, with over 100 local people employed during the project, including electricians, carpenters, farm workers, traffic controllers and maintenance workers

Embracing New Technology

Speaking at the delivery event for VNI, Transgrid CEO Brett Redman outlined why the technology was so attractive to the transmission network: “Australia’s energy transition is already happening — faster than many thought possible — and we need to work both faster and smarter to help the transition happen. The speed at which the energy transition is accelerating means we must embrace new technology and innovate, and VNI is a perfect example of how Transgrid is doing just that.

“The project has unlocked 170 MW of additional energy, enough to power more than 30,000 homes — and we haven’t needed to build any new transmission lines to do it,” Redman added. “VNI will enable the integration of renewables, increase competition among generators, drive down electricity prices and support the decarbonisation of Australia’s economy.”

“And this is just the first step. There is huge potential for power flow control to enable many major projects central to Australia’s energy transition.”
Transgrid continues to look at the use of modular power flow control solutions as part of its network development process.

Oliver King is a seasoned project director with 18 years of experience across multiple industries, including oil and gas, utilities and transmission — having now spent 18 months at Transgrid in Sydney, Australia. King’s goal is to tangibly deliver value-added solutions to problems — applied innovation in its truest sense.

Aidan Lawlor is a professional engineer with more than 20 years of experience in senior management, project delivery and stakeholder engagement roles in the Australian and Irish energy industries. Lawlor leads Smart Wires Inc.’s Asia Pacific team as general manager, working closely with Transgrid and
other transmission owners in the region to implement modular power flow control technology.