Oakey Power Station

Client: Confidential
Location: Queensland
Date: 2024–25 

Providing power systems expertise for modernising protection systems, supporting ongoing reliable electricity generation

Background 

Oakey Power Station, 150 km west of Brisbane on Queensland’s Darling Downs, began commercial operations in 1999. The station has two open-cycle gas turbines with a combined output of 332 MW. The station plays an important role in the transition to renewables by providing fast-ramping support for intermittent generation, such as solar and wind. To minimise environmental impact, it runs only during times of peak energy demand, supplying electricity to the National Electricity Market via the nearby Oakey Substation. 

The existing generator protection and synchroniser systems at Oakey had been in service for more than two decades and support for these systems had become limited. To ensure ongoing and reliable operation of the facility, and to mitigate the risk of unrecoverable failures, our client sought to replace these existing systems while also upgrading from a complementary protection scheme to a fully redundant protection scheme.  

Solution 

Entura was engaged with a broad scope covering the design, implementation and commissioning of these systems. This included protection and synchroniser design, purchase and supply of the new protection equipment, entering all the calculated settings into the purchased equipment, and installation, testing and commissioning of the new protection equipment.  

While most of the existing protection settings were easily translated from the old systems and implemented in the new protection, translation of the loss of field protection was more difficult and loss of synchronism protection needed to be turned on. Entura’s specialist personnel solved these challenges, developing appropriate, fit-for-purpose settings for these more complex elements.  

Our team also analysed the pole slip and loss of field protection. The protection was tested against impedance loci for real faults as determined in the PSSe software, and was initially analysed in Excel. Subsequently, PSSe models were created of the pole slip and loss of field protections. 

The next stage of our involvement was to complete a reduced version of a connection study, which is usual when the protection for a power station is replaced. The outcome of this process is known as a 5.3.9 process. Entura’s highly experienced power systems team undertook this work, including model development, inclusion of voltage and impedance protections into the model, and detailed power system studies in PSSE-PSCAD to demonstrate compliance with AEMO’s Generator Performance Standards (GPS) requirements. 

Outcome 

Our extensive experience and expertise in power systems and grid connection enabled our client to obtain 5.3.9 alteration approval and to successfully satisfy all the requirements of Powerlink and the Australian Energy Market Operator (AEMO). 

Our client can now have greater confidence in the ongoing and reliable operation of the power station, as the facility continues to support dependable, adequate electricity supply during peak demand.