TransGrid has recently published a Project Specification Consultation Report for maintaining reliable supply to Broken Hill.
Part of TransGrid’s south western transmission network, Broken Hill is currently supplied by a single 220 kV transmission line, ‘Line X2’, from Buronga.
When Line X2 is out of service due to a planned or unplanned outage, electricity supply to Broken Hill is supported by two gas turbines owned by Essential Energy to avoid involuntary load shedding (these turbines each have a nameplate rating of 25 MW). TransGrid relies on these gas turbines to meet the NSW Electricity Transmission Reliability and Performance Standards 2017 set by the NSW Energy Minister and regulated by the NSW Independent Pricing and Regulatory Tribunal. In accordance with these standards, Essential Energy’s gas turbines allow TransGrid to operate its network so as not to expect more than 10 minutes of unserved energy (EUE) per year at average demand.
Essential Energy has notified TransGrid of its decision to divest the gas turbines located at Broken Hill. If no action is taken by TransGrid, this will result in the required reliability of supply to Broken Hill not being maintained, and involuntary load shedding when Line X2 is on planned or unplanned outage.
TransGrid considers this a ‘reliability corrective action’ under the RIT-T as the identified need is to ensure that the externally-imposed reliability standards for Broken Hill continue to be met.
In order to efficiently avoid involuntary load shedding and meet the reliability standards TransGrid has adopted a two-step approach.
- Step 1 – Establish a short-term non-network support solution, via an Expression of Interest (EOI) process. The EOI was issued in October 2019 with responses due in November 2019. This short-term non-network support solution will be required to be available:
- immediately, and
- until the long-term solution, which will be identified under this the RIT-T process is operational. This could be up to three years.
- Step 2 – Establish a long-term solution via the RIT-T. This document is the first step in the RIT-T process, which will consider all credible long-term options including traditional network, innovative, and non-network solutions. It may take up to three years for the long-term solution identified under the RIT-T process to be operational.
TransGrid’s revenue determination for the 2018-2023 regulatory control period includes a contingent project for the reliability of supply to Broken Hill. This contingent project is to provide additional capacity to supply Broken Hill in an event that the total 220 kV and 22 kV load at Broken Hill exceeds the capacity of the back-up gas turbines owned by Essential Energy and EUE exceeds the allowance.
TransGrid has put forward five credible options for consideration in this Project Consultation Specification Report:
- Option 1: Network support service
- Option 2: Acquire existing gas turbines from Essential Energy
- Option 3: New gas turbines at Broken Hill
- Option 4: Establish a second single circuit 220 kV transmission line from Buronga to Broken Hill
- Option 5: Local storage and grid stability devices that provide inertia and system strength at Broken Hill
Alongside the PSCR, TransGrid has released an EOI to provide additional detail on the technical requirements for network and non-network options.
TransGrid welcomes written submissions on materials contained in the PSCR and the accompanying EOI. 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 31 January 2020.
In accordance with the requirements of the Rules, a summary of the Project Specification Consultation Report is made available on the AEMO website.
A copy of the Project Specification Consultation Report can be obtained from TransGrid's website or by emailing regulatory.consultation@transgrid.com.au
Submissions in response to this Project Specification Consultation Report are required by the closing date of 31 January 2020.