Improving stability in south-west NSW

South-western NSW has seen significant growth in renewable generation connections to the transmission network. This trend, which is forecast to continue, is having an impact on how this part of the power system operates as more power from new renewable generation flows into the transmission network. These changes in power flows are expected to lead to an increasing risk of power system instability going forward.

Transgrid has identified the opportunity to strengthen the transmission network and provide wider market benefits to the National Electricity Market (NEM). To test the economic viability of different solutions, we are applying the Regulatory Investment Test for Transmission (RIT-T) to options for improving stability in the south-western New South Wales power system.  

To be given final investment approval, Transgrid must show that the preferred option for improving stability in south-western NSW will deliver the greatest net benefits to energy consumers. The net benefits delivered by the project are assessed using the Regulatory Investment Test for Transmission (RIT-T) administered by the Australian Energy Regulator (AER).

The RIT-T assesses network and non-network solution options from a technical and economic perspective by:

• Informing stakeholders of the investment need and proposed options to address this need
• Testing the market for alternative and more efficient solutions
• Explaining to stakeholders the basis on which the preferred option has been selected.

We have now completed the final stage of the RIT-T and after assessing multiple options, identified that a new Darlington Point to Dinawan 330 kV transmission line coupled with an interim 3-year network support contract with a battery energy storage system (BESS) solution is the preferred solution.

Project Specification Consultation Report

In July 2020, the Project Specification Consultation Report (PSCR) was published. The PSCR detailed the need to improve stability on the south-western NSW power system and describes credible options to meet the need, including technical characteristics that would be required of a non-network option.

We received submissions from seven parties in response to the PSCR. The following submissions are approved for publication: 

Comments from the submissions received in response to the PSCR were considered when preparing the Project Assessment Draft Report (PADR), published in September 2021.  The PADR includes a full quantitative analysis of the proposed options and expected net market benefit across a range of scenarios and sensitivities. We have published the following supporting documents:

PADR supporting documents

We invited written submissions on the material contained in the PADR. We received submissions from six parties in response to the PADR, one of which is confidential. Submissions approved for publication are from: 

• Darlington Point Solar Farm
• Iberdrola Australia 
• Public Interest Advocacy Centre 
• Reach Solar Energy 
• RWE Renewables 

We engaged further with parties to confirm the status and technical feasibility of the options, which involved the provision of further information from these parties.

Thank you to those who made a submission throughout the RIT-T process.

In June 2022, we have published the Project Assessment Conclusions Report (PACR) for Improving Stability in South Western NSW.

The PACR has been prepared as the final step in the Regulatory Investment Test for Transmission (RIT-T) process and follows the Project Assessment Draft Report (PADR) published in September 2021.

The assessment in this PACR finds that a new Darlington Point to Dinawan 330 kV transmission line coupled with an interim 3-year network support contract with a battery energy storage system (BESS) solution (‘Option 4’) is the preferred option for meeting the identified need across all scenarios and sensitivities assessed.

PACR Supporting Documents

• EY Market Modelling Report
• NPV Model Outcomes

If you have any questions about the project, please contact network.solutions@transgrid.com.au or phone 1800 222 537.

The preferred option presented within the Project Assessment Conclusion Report involved a temporary battery solution and then the implementation of a new transmission line. This option has been superseded by a non-network standalone battery option that leverages already existing assets. The Notice of Change to Non-Network Option outlines the change.