Transgrid Amended PACR: Maintaining Reliable Supply to the North West Slopes area

Market Network Service Provider
StageProject Assessment Conclusions Report
ConvenorAEMO NSP
Accepting submissions?No

Transgrid has published an amended Project Assessment Conclusions Report (PACR) for Maintaining Reliable Supply to the North West Slopes area in Northern NSW. The release of this amended PACR follows the AER’s decision on a dispute notice from the Public Interest Advocacy Centre (PIAC) on the initial PACR, which was published in June 2022. This amended PACR therefore updates the assessment and PACR in-line with the AER dispute determination.

The preferred option identified in this amended PACR remains unchanged from the initial PACR.

Transgrid’s latest forecasts indicate that electricity demand is expected to increase substantially in the North West Slopes area going forward due to a number of substantial industrial loads that are anticipated to connect, as well as underlying general load growth in Narrabri and Gunnedah. 

Schedule 5.1.4 of the National Electricity Rules (NER) requires Transgrid to plan and design equipment for voltage control to maintain voltage levels within 10 per cent of normal voltage.  The NER also requires the power system to be operated in a satisfactory operating state, which requires voltages to be maintained within these levels, both in normal operation and following any credible contingency event.

Transgrid has undertaken planning studies that show that the current North West Slopes network will not be capable of supplying the combined increases in load in the area without breaching the NER requirements. Transgrid’s planning studies also show that the increased demand will also lead to thermal constraints going forward, particularly during times of low renewable generation dispatch in the region.

If the longer-term constraints associated with the load growth are unresolved, it could result in the interruption of a significant amount of electricity supply under both normal and contingency conditions due to the voltage and thermal limitations in the area. 

The assessment outcome in this amended PACR remains unchanged from the initial PACR and finds that a non-network solution provided through a Battery Energy Storage System (BESS) at the Gunnedah 132 kV substation and the installation of a third transformer at Narrabri 132 kV substation in the near-term, along with upgrades to existing transmission lines in the longer term, is the preferred option for meeting the identified need.

In accordance with the requirements of the Rules, a summary of the amended Project Assessment Conclusions Report is made available on the AEMO website. A copy of the amended PACR can be obtained from Transgrid’s website or by emailing

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