TransGrid PSCR: Maintaining reliable supply to North West Slopes area

Market Network Service Provider
StageProject Specification Consultation Report
ConvenorAEMO NSP
Accepting submissions?No
Submissions close15/07/2021

TransGrid has recently published a Project Specification Consultation Report (PSCR) for maintaining reliable supply to the North West Slopes area of northern NSW.

The latest demand forecasts for the North West Slopes indicate that electricity demand is expected to increase substantially in the area going forward. This is driven by a number of substantial industrial loads anticipated to connect, as well as underlying general load growth in Narrabri and Gunnedah. 

TransGrid’s power system studies forecast that the expected load growth will reach voltage stability and thermal limits on the 132 kV supply network in the North West Slopes area if action is not taken by 2024. 

Schedule 5.1.4 of the 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 undertook 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 and that voltage-limited constraints will have to be applied in the 132 kV supply network if action is not taken. 

Moreover, in addition to the voltage constraints identified, TransGrid’s planning studies show that the increased demand will also lead to thermal constraints going forward, particularly during times of low renewable generation dispatch in the region.

This RIT-T therefore examines various network and non-network options for relieving these constraints going forward to ensure compliance with the requirements of the NER and provide the greatest net benefit to the market. 

TransGrid considers there are four broad types of credible network options that have the potential to meet the identified need from a technical, commercial, and project delivery perspective. Each of the credible network options outlined in this PSCR requires the installation of a third 60 MVA 132/66 kV transformer at Narrabri due to the firm supply capacity of the existing transformers at this location being exceeded under all scenarios. 

Aside from the new 132/66 kV transformer at Narrabri, the credible network options differ in the near-term by where, how and when new capacity is added to the North West Slopes region. In particular, TransGrid currently considers there to be four broad types of credible options, which cover:

  1. uprating the existing line 969 from Tamworth to Gunnedah;
  2. installing new single or double circuit transmission lines between Tamworth and Gunnedah;
  3. rebuilding the existing line 969 from Tamworth to Gunnedah to be a double circuit line; and
  4. connecting to a potential new private transmission project in the Gunnedah area called the New England Transmission Infrastructure (NETI). 

TransGrid considers that non-network solutions may be able to form credible options for this RIT-T, either as standalone options or in combination with network options (or components of these options). Together with this PSCR, TransGrid has released an Expression of Interest (EOI) to provide additional detail on the technical requirements for non-network options and seek submissions from proponents of these options. Details for access to the EOI are available via TransGrid’s website.  

TransGrid welcomes written submissions on materials contained in the PSCR. Submissions are particularly sought on the credible options presented and from potential proponents of non-network options that could meet the technical requirements set out in the PSCR. Submissions are due on 15 July 2021. 

In accordance with the requirements of the Rules, a summary of the PSCR is made available on the AEMO website. A copy of the PSCR can be obtained from TransGrid’s website or by emailing

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