TransGrid has recently published a Project Assessment Conclusions Report for maintaining compliance with performance standards applicable to Tuggerah substation secondary systems.
TransGrid has identified that the secondary systems at Tuggerah substation have reached a condition that reflects the end of serviceable life. As it is superseded by new technology at the manufacturer level and the existing technology becomes obsolete, spare parts become scarce and the ability of any primary asset connected to the substation to reliably operate will be at risk.
Tuggerah substation will continue to play a central role in the safe and reliable operation of the power system throughout and after the transition to a low-carbon electricity future. It forms part of the Newcastle and Central Coast network which supports the flow of energy between generation on the Central Coast and the northern suburbs of Sydney. Tuggerah substation is a customer connection point supplying the Ausgrid 132 kV network in the area inclusive of Gosford, Ourimbah, Berkeley Vale and Wyong.
Provision of redundant protection schemes to ensure the transmission system is adequately protected is a Network Performance Requirement under Schedule 5.1 of the National Electricity Rules (NER), therefore the condition issues affecting the secondary systems at Tuggerah substation must be addressed. If the failure to provide functional secondary systems due to technology obsolescence is not addressed by a technically and commercially feasible credible option in sufficient time (by 2022/23), the likelihood of not recovering from secondary systems faults and not maintaining compliance with NER performance requirements will increase.
Continued deterioration of the secondary systems at Tuggerah substation will accelerate the depletion of spares which will lead to a situation where TransGrid is unable to operate the secondary systems in accordance with clause 4.6.1 of the NER. The proposed investment will enable TransGrid to continue to meet the standards for secondary systems availability set out in the NER, and to avoid the impacts of taking primary assets out of service. Consequently, it is considered a reliability corrective action under the RIT-T.
TransGrid published a Project Assessment Conclusions Report (PACR) for maintaining compliance with performance standards applicable to Tuggerah substation secondary systems in June 2020. No submissions were received in response to the PSCR during the consultation period which closed in August 2020.
TransGrid considered three credible options that would meet the identified need from a technological and project delivery perspective.
Since the PSCR, TransGrid has updated the discount rates and inflation escalation (including capex). Neither of these elements has made a material impact on the outcome. Option 2 — complete in-situ replacement of protection and control systems at Tuggerah substation — remains the preferred option. This option is estimated to have a capital cost of $5.9 million +/- 25% and is expected to be completed by 2022/23. TransGrid is the proponent of the proposed network project.
In accordance with the requirements of the National Electricity Rules, a summary of the PACR is made available on the AEMO website. A copy of the PACR can be obtained from TransGrid’s website on the Regulatory Investment Tests page or by emailing RIT-TConsultations@TransGrid.com.au