Overview

Transgrid, as the System Strength Service Provider (SSSP) for NSW, is responsible for ensuring sufficient system strength is available to maintain power system stability in NSW.

In a network without adequate system strength there are inherent stability issues. Generators may be unable to remain connected during disturbances on the power system, control of the system voltage becomes more difficult, and protection systems that ensure safe operation of the network may not operate correctly.

The retirement of NSW’s coal generators and the growth in inverter-based resources in the coming decade is driving an urgent need to add new sources of system strength to the power system.

We have therefore commenced assessment of options to ensure we meet the NER requirements and continue to ensure a safe, secure and reliable power system. We consider that this will enable us to identify the optimal portfolio of solutions to meet both the short-term and long-term needs.

The System Strength Rule Change has established new requirements for connecting parties to meet. A summary of these new requirements can be found on the System strength for network connections page.

RIT-T status

Transgrid is developing a portfolio of system strength solutions to meet our regulatory obligations and to maximise net market benefits. The net benefits delivered by the project are assessed via the Regulatory Investment Test for Transmission (RIT-T) administered by the Australian Energy Regulator (AER). The RIT-T is a formal consultation process designed to:

  • Inform stakeholders of the investment need and proposed options to address it
  • Test the market for alternative and more efficient solutions
  • Explain to stakeholders the basis on which the preferred option has been selected.

The RIT-T consultation process has three stages:

Further details on each stage of the RIT-T are provided further below.

Non-network system strength solutions

Our modelling shows that non-network solutions will play a core role in providing system strength into the future and will be brought into the portfolio of solutions via network support contracts. Transgrid has developed documents to provide further information to non-network proponents to help them better understand their opportunity to provide system strength services.

Assessment of non-network option feasibility

As part of the RIT-T assessment, Transgrid must assess and confirm the technical and commercial feasibility of each candidate before including it as a credible option for assessment in the Project Assessment Conclusions Report (PACR) market modelling. Responses to the technical component of the EOI are now closed.

To complete the final stage in this process, we requested non-network proponents to provide confidential submissions in response to Transgrid’s EOI. This questionnaire invites non-network proponents to submit updated information for system strength services and allows Transgrid to evaluate the feasibility of non-network options.

Responses to both the technical component and the commercial component of the EOI are now closed.

Key documents and Information for non-network proponents

The below documents were published by in parallel with the PADR to provide further insights into the RIT-T, procurement and contracting process and technical specifications.

Document

Description

Information for system strength non-network option proponents

An explanation of the RIT-T, procurement and contracting process, areas of interest for new EOIs and high-level technical guidance for system strength services

Information for system strength non-network option proponents - EOI commercial addendum

An explanation of the purpose and structure of the request for non-network proponents to update the commercial component of their EOI

EOI response questionnaire (commercial component)

An Excel workbook that gives proponents the opportunity to update or submit new EOIs (commercial component)

EOI response questionnaire (technical and economic cost information)

An Excel workbook that gives proponents the opportunity to update or submit new EOIs (on technical and economic cost information)

Technical performance and power system modelling requirements for synchronous machines

Detailed technical performance and power system modelling requirements for synchronous machines (for consultation)

Technical performance and power system modelling requirements for grid-forming BESS

Detailed technical performance and power system modelling requirements for grid-forming inverters (for consultation)

Effectiveness Factors

An Excel workbook that indicates the effectiveness of different locations for system strength provision

Industry briefing - Guidance for Non-Network Proponents: Slide Pack

In June, Transgrid hosted an industry briefing containing guidance for non-network proponents.

Industry briefing – Guidance for Non-Network Proponents (EOI commercial addendum): Slide Pack 

In August, Transgrid hosted an industry briefing to provide an overview and answer questions specifically on the commercial component of the EOI.

Transgrid System Strength Non-Network Proponent EOI FAQ update

In addition to the Frequently Asked Questions in Appendix A of 'Information for system strength non-network option proponents - EOI commercial addendum' document, this document sets out some further Frequently Asked Questions.

For any questions, please contact the system strength project team at systemstrength@transgrid.com.au. 

RIT-T Reports

Supplementary Project Assessment Draft Report

The Supplementary Report to the Project Assessment Draft Report (PADR), published in October 2024, offers an opportunity to assesses the potential impacts of recent developments on the preferred option identified in the PADR and allows the industry to consult on these developments ahead of the development of the final stage of the RIT-T, the Project Assessment Conclusions Report (PACR). This report has modelled three key sensitivities:

  • Sensitivity 1: Revised retirement date of Eraring Power station;
  • Sensitivity 2: Inverter-based resource forecasts within AEMO’s Final 2024 ISP, including revised timing for the New England REZ;
  • Sensitivity 3: Increasing the robustness of the portfolio of system strength solution by bringing forward the commission on synchronous condensers.

Submissions on the materials contained in the Supplementary Report are now closed and will be addressed in the PACR.

Project Assessment Draft Report

The Project Assessment Draft Report (PADR), published in June 2024, provides transparency into the planning considerations for investment options to maintain adequate levels of system strength in the NSW power system, and the associated market benefits. A key purpose of this PADR, and the RIT-T more broadly, is to provide interested stakeholders the opportunity to review the analysis and assumptions, provide input to the process, and have certainty and confidence that the preferred option (or portfolio of solutions in this case) has been robustly identified as optimal.

Submissions and Expressions of Interest received in response to the PSCR were considered when preparing the PADR.  The PADR includes a full quantitative analysis of the proposed options and expected net market benefit across a range of system strength portfolio options and sensitivities. We have published the PADR and associated supporting documents: 

 Supporting Documentation

Project Specification Consultation Report

In December 2022 we published a Project Specification Consultation Report (PSCR), the first step in the RIT-T process. The PSCR details the need to meet system strength requirements in NSW and describes credible options to meet the need, including technical characteristics that would be required of a non-network option.

RIT-T consultation responses

Transgrid have engaged in a consultation process following publication of the PSCR and PADR to provide industry and stakeholders with the opportunity to provide feedback on the credible options presented, issues addressed, proposed methodology and preferred option outcomes.

  • In response to the PADR, we received submissions from two parties throughout the six-week consultation period: EnergyCo and Tesla.
  • In response to the PSCR, we received submissions from five parties throughout the twelve-week consultation period, one of which is confidential: Energy Australia, Origin Energy, Smart Wires, Tesla.

Submissions to the PADR and Supplementary PADR will be addressed in the PACR, planned to be published mid-2025.