Transgrid has recently published a Project Specification Consultation Report (PSCR) for maintaining reliable supply to the Deniliquin, Coleambally and Finley area.
The Australian Energy Market Operator (AEMO) forecasts that minimum demand in NSW will rapidly decline over the next 10 years due to ongoing growth in distributed solar (PV) generation. In south west NSW, growth in small to large scale embedded generation connecting to the Essential Energy network is forecast to continue, driving declining minimum demand in this region.
The south west NSW region is supplied by four 132 kV transmission lines which form a link between Wagga Wagga and Darlington Point, via Deniliquin, Coleambally, and Finley. Our power system studies show that the declining minimum demand in these areas mean that the electricity transmission system in these areas is at risk of exceeding allowable voltage levels during times of low demand and in particular when nearby solar farms are unable to provide reactive power support.
In addition to the excessive voltage issues identified by Transgrid, AEMO have declared an immediate Network Support and Control Ancillary Services (NSCAS) gap of 2 MVAr absorbing reactive power in the Coleambally region for overnight when nearby solar farms are not available.
We are required to manage the risk of system voltages exceeding their allowable limits as set out in the National Electricity Rules (NER) and procure services to meet the NSCAS gap declared by AEMO. Consequently, it is considered 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 2 (Install two 11 MVAr 66 kV reactors at Deniliquin) – is the preferred option to meet the identified need.
The estimated capital cost of this option is approximately $8.1 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 that could meet the technical requirements set out in this PSCR. Submissions are due on 31 August 2022.
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