System security and the network operability of the power system underpin the reliability of the transmission network and the balance of supply (generation) and demand (load) required to meet customer needs. Power system security needs are technically complex, at times may be challenging to address, and are critical to the ongoing stability of the transmission network, particularly as the mix of generation changes during the energy transition.
The Australian Energy Market Operator (AEMO) and Powerlink are responsible for the planning and delivery of power system security services in Queensland.
AEMO’s annual Transition Plan for System Security considers the need for services across all regions of the National Electricity Market (NEM), and evaluates requirements for system strength, inertia and Network Support and Control Ancillary Services (NSCAS). Powerlink makes system security services available to AEMO, using network or non-network solutions, or a combination of both.
To ensure we deliver cost-effective system security solutions, Powerlink consults with NEM participants and other interested parties as part of the procurement process. If the solution is needed within 18 months of being identified by AEMO, Powerlink may issue an Expression of Interest (EOI) for non-network solutions. Where the service is needed greater than 18 months away, Powerlink will undertake a Regulatory Investment for Transmission (RIT-T) to assess the feasibility of network and non-network solutions.
System Strength RIT-T
In June 2025, Powerlink completed a RIT-T to address system strength requirements in Queensland from December 2025. The Project Assessment Conclusions Report (PACR) for the System Strength RIT-T is available below, and further information and reports are available on the RIT-T Consultations page.
Project Assessment Conclusions Report
Further information
System strength is a measure of the stability of a power system under all reasonably possible operating conditions. It describes a system’s overall performance and its ability to recover quickly from sudden events.
Synchronous generators – like coal, gas and hydro power stations – provide system strength when they generate. System strength can also be provided by machines called synchronous condensers.
Asynchronous generators – like wind and solar – do not provide system strength and require system strength from another source.
While a system strength shortfall is very unlikely to impact the ongoing supply of electricity to customers in Queensland, it may limit an asynchronous generator's capability to export power to the grid. Queensland has a broad mix of generation types located across various regions in the state which can be accessed through our transmission network in the unlikely event that supply is impacted.
Inertia is the ability of the system to resist sudden frequency deviations and slow the rate of change of frequency. The energy required to counter significant frequency deviations caused by an imbalance in power supply and demand during a contingency event can come from either the kinetic energy stored in the momentum of synchronous machines or from an instantaneous, rapid and automatic injection of energy from another source (such as synthetic inertia from a battery). Similar to system strength, inertia has traditionally been provided by synchronous generators, and additional remediation is now needed to ensure the power system has sufficient inertia to remain secure.
AEMO describes NSCAS as non-market ancillary services that may be delivered to maintain power system security and reliability, or to maintain or increase the power transfer capability of the transmission network. For example, these may include services which can be provided by plant with reactive power absorption capability such as synchronous generators or battery energy storage systems.
Previous Power System Security EOIs
Fault Level Shortfall at Gin Gin
System Strength Services at Ross
NSCAS gap in southern Queensland
Related information
Powerlink's System Strength Study
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