QNI nears finish line with Tamworth substation completion

An aerial view of the Transgrid QNI Tamworth substation
An aerial view of the Transgrid Tamworth substation

Transgrid’s Queensland-NSW Interconnector (QNI) upgrade is nearing completion, with civil works now finalised at the Tamworth substation—the largest of five substations to be overhauled.

Transgrid executive manager of delivery Craig Stallan said, “QNI is 90 per cent complete and we’re on track to have all project works completed by May.

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“Since the Australian Energy Market Operator (AEMO) first recognised QNI as a priority in their 2020 Integrated System Plan, and work started later that year, we’ve increased the Tamworth substation footprint by 50 per cent to accommodate the technology required to help future-proof this part of our grid.” 

Technology called Static Var Compensators (SVCs), which are vital in controlling reactive power flows on the grid, have been installed at Tamworth and Dumaresq substations. A team of experts from Siemens Energy in India arrived in December and once their work is complete the SVCs can be energised and tested. Following this, the project will be handed over to AEMO for rigorous testing. 

Over 300km of transmission lines have been uprated to higher temperature ratings, which means they can now accommodate higher power transfers while maintaining statutory ground clearances for the higher temperatures. Fifty-eight transmission towers were replaced and 131 existing towers were uprated as part of the project. 

“The QNI transmission lines were uprated to 120 degrees Celsius, which will allow higher power flows between the states, vital in times of extra demand, and it will help to stabilise energy prices,” Stallan said. 

QNI also involves the installation of new capacitor banks, SVC transformers and associated 330kV switch bays. The capacitor banks provide additional reactive power, while the SVC regulates the reactive power on the grid. 

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“This technology will optimise the real power flows on the transmission lines as well as providing grid stability,” Stallan said. 

“For the past two years we have been part of the local communities where major substation upgrades have occurred, particularly at Tamworth, Armidale and Dumaresq, employing up to 170 extra people at any one time on QNI.”

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