Transgrid has published the Project Assessment Conclusions Report (PACR) for Maintaining reliable supply to the Deniliquin, Coleambally and Finley area in south west NSW. The PACR has been prepared as the final step in the Regulatory Investment Test for Transmission (RIT-T) process and follows the Project Specification Consultation Report (PSCR) published in June 2022.
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. Transgrid’s 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 Reliability and Security Ancillary Services (RSAS) 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 Schedule 5.1.4 of the National Electricity Rules (NER) and procure services to meet the RSAS gap declared by AEMO.
The assessment in this PACR finds that the installation of two 11 MVAr 66kV reactors at Deniliquin substation is the preferred solution to meet the identified need.
In accordance with the requirements of the Rules, a summary of the Project Assessment Conclusions Report is made available on the AEMO website. A copy of the PACR can be obtained from Transgrid’s website or by emailing firstname.lastname@example.org.