A large-scale blackout of the power system is called a system black event. These events are extremely rare.

System black events can occur when a sudden, unexpected loss of a major source of supply causes very rapid changes in system frequency which undermines the security of the electrical system. Generators and networks automatically disconnect or ‘trip’ when there is a very rapid change in frequency in order to protect equipment and personnel from harm.

Following a large-scale blackout, AEMO, who coordinate the restart and restoration process, follow emergency procedures set out in a system restart plan.

The AEMC has released a consultation paper on a proposed rule change to clarify how AEMO shares information about system restart plans with generators, networks and other key parties involved in restoring the electricity system after a widespread blackout. Further information regarding the consultation process is available here.

Under the National Electricity Rules, a system restart plan is classified as confidential information. AEMO proposes amending the rules to give it express authority to share and discuss system restart plans with relevant parties including generators contracted to provide system restart services, network businesses and jurisdictional system security coordinators.

AGL broadly supports the rule change as a mechanism to increase industry awareness and the operational efficiency of system restoration activities. We agree that increased coordination and industry readiness will better position AEMO to manage these unique events; however, we consider that further clarity is required on some issues raised within the proposal.

AGL’s submission to the rule change proposal is available here.