Transgrid has recently published a Project Specification Consultation Report (PSCR) for improving voltage control in Southern New South Wales.
AEMO’s Electricity Statement of Opportunities (ESOO) 2024 report shows that Minimum Demand in NSW will continue to decline over the next couple of years. This value is expected to be less than 1000 MW (Summer and Shoulder) in the FY 2029/30 under the 50% Probability of Exceedance (POE) Central Scenario. The reduction in minimum demand is already causing high voltage issues, especially at some switchyards where the maximum voltage rating is lower than 1.1 p.u.
The NSW southwest subsystem is also experiencing high voltage issues at times of low demand due to a reduction in Wagga area load. This can be primarily attributed to the Norske Skog paper mill ceasing operations (about a 100 MW load decrease). Accordingly, there are over-voltage issues at Balranald substations at times of overnight light load conditions, in particular in the event of the contingent trips in that region.
The identified need for this RIT-T is to maintain voltage levels in southern NSW by managing the risk of excess voltage levels due to declining minimum demand. There is an increasing likelihood of non-compliance with NER and NSW reliability standards without investments to address this need. We are required to maintain compliance with Schedule 5.1.4 of the NER and the NSW Electricity Reliability and Performance Standards 2017. Consequently, we consider this a ‘reliability corrective action’ under the RIT-T.
In the PSCR Transgrid presented two credible network options that would meet the identified need from a technical, commercial, and project delivery perspective. The optimal commercially and technically feasible option presented in this PSCR – Option 1 (Install 1 x 50
MVAr Shunt Reactor at Kangaroo Valley 330 kV switching station and Install 1 x 20 MVAr Shunt Reactor at Balranald 220 kV station) – is the preferred option to meet the identified need.
The estimated capital cost of this option is approximately $13.4 million +/- 25 per cent. Transgrid is the proponent of the proposed network project.
Transgrid welcomes written submissions on materials contained in this PSCR. Submissions are particularly sought on the credible options presented and from potential proponents of non-network options in the Kangaroo Valley and Balranald areas that could meet the technical requirements set out in this PSCR. Submissions are due on 20 February 2025.
In accordance with the requirements of the National Electricity 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 regulatory.consultation@transgrid.com.au