Frequently asked questions

Yes. The trial cutover helped identify defects in a controlled pre-production environment, allowing AEMO to coordinate remediation and validation before implementation in the production environment.

Yes. Participants can continue to monitor and test in pre-production. Some reports or outcomes may not fully reflect the intended PEC-MI design until identified defects are resolved. Participants should raise any observations or issues through established support channels.

The current implementation plan continues to target commencement of physical loop operations from 1 October 2026 and settlement arrangements from 1 November 2026. AEMO will advise participants of any changes or contingency arrangements if required.

AEMO will assess readiness in line with the published NEM Reform Program readiness approach, including testing outcomes, defect status, operational readiness activities and participant feedback. AEMO will communicate any changes or contingency arrangements if required.

Participants should review published implementation information, complete any required system or process changes, participate in relevant testing, and ensure operational teams are familiar with cutover arrangements.

Participants should test impacts relevant to their organisation and confirm their systems and processes operate as expected under the PEC-MI market configuration.

AEMO may consider deferring implementation dates if unresolved issues create unacceptable market, operational or implementation risk.

Participants should monitor AEMO communications, follow published cutover instructions and have appropriate operational support available if required.

AEMO is managing risks related to readiness, defect remediation, testing outcomes, cutover execution and operation of market systems in production.

AEMO will validate the PEC-MI configuration through testing before go-live to support accurate representation of the new network configuration in market systems.

PEC-MI enables market systems to reflect new network capability. Actual outcomes for prices, congestion and power flows will depend on conditions at the time, including demand, bids, generation availability and network constraints.

AEMO will provide implementation communications, operational support arrangements and post-go-live monitoring during the stabilisation period.

Participants should raise issues as early as possible through established support channels so they can be assessed, prioritised and resolved efficiently.

The identified defects were found in pre-production. AEMO will deploy and validate planned fixes in the pre-production environment before progressing any relevant changes to production.

Automated negative residue management (NRM) changes are now planned for mid to late- September 2026 following further remediation of identified defects.

The planned commencement dates for physical loop operations and settlement go-live remains unchanged.

Yes. The NRM loop flow flag is expected to show a value in pre-production, including when the interconnector is not active. AEMO is reviewing this behaviour and will provide further information if required.

AEMO is confirming IRSR reporting requirements, including the availability of relevant information in NEMWeb pre-production for participant testing. Further details will be provided when available.

Yes. NRM can only be activated when the relevant loop flag is set.

Registration is planned for August, with the interconnector effective from October. Full energisation and testing are expected to start in November.

Loop flow equations help AEMO reflect how electricity will physically move through the network once PEC creates a new loop. This supports dispatch outcomes that better align with actual network flows.

A freeze on system normal constraint changes starts in late September, focusing on PEC-related updates, and lifts after the October changeover. 

PEC mainly impacts constraints near its location; regions like Tasmania and Queensland are largely unaffected. 

AEMO will continue to set interconnector limits using the most relevant binding constraint. Loop flow equations will inform dispatch but will not be used as the limit setters for interconnectors.

AEMO will update its public equipment ratings file to include PEC lines. 

Yes, market notices will be issued for major constraint changes and equipment commissioning. 

Resources like the congestion information resource and equipment ratings will be updated; AEMO is considering additional information packs. 

The microslice approach would make the new network loop less visible to the market and harder to reflect transparently in constraints and settlements. AEMO is using loop flow equations to provide clearer visibility of how PEC affects dispatch.

The AEMC Rule requires the PEC loop to be reflected in dispatch. Loop flow equations provide a practical way to represent that loop in the current dispatch systems.

AEMO developed the loop flow constraints using historical and simulated data. Local generator terms were placed on the right-hand side of the equation to avoid technical orientation issues across regions, while preserving the intended relationship between network flows and dispatch.

AEMO tested whether local load materially affects the loop flow equations. The analysis did not show a meaningful additional impact, but AEMO will continue to monitor this after PEC Stage 2 is commissioned.

The equations are designed to represent the relationship between network flows and dispatch, rather than forecast exact real-time flows. AEMO will monitor actual performance after implementation and adjust future constraint versions if needed.

Rebuilding NEMDE or adding a full network model would take several years. Loop flow equations provide a practical near-term approach that can be implemented in existing systems, tested, monitored and refined over time.

Transgrid will manage phase-shifting transformer tap changes and advise AEMO. AEMO will use operational experience to determine whether any changes to this approach are needed.

In pre-dispatch, AEMO will reflect Transgrid’s approach where possible and refine settings as operational experience is gained.

For PASA, AEMO will consider tap settings when assessing reserves and will review settings if Lack of Reserve conditions occur. Taps are not expected to be material before the 350 MW hold point, but AEMO will monitor outcomes and may advise the Network Service Provider if changes are needed.

AEMO has tested the approach with consultants, system updates, dispatch training simulations and pre-production processes. AEMO expects the constraints to be ready for 1 October and will monitor performance after go-live.

AEMO will manage negative settlement residues in line with existing settlement processes and will provide further information to industry if any PEC-specific arrangements are required.

No. Although participants may observe PST tap position changes in Pre Prod, these movements are currently made manually and are not driven by the automated PST control scheme. Transgrid has confirmed that the PST control scheme is not yet in service. Also note, the PST control scheme is intended for PEC2 only and was not introduced as part of the current PEC1 arrangements.

AEMO is aware of this observation and is assessing the application of the current minimum LHS coefficient threshold to loop flow equations. Given loop flow equations are a new constraint formulation introduced for PEC, they remain subject to ongoing testing and validation. AEMO has not yet reached a final position on whether any changes to the equation formulation approach or the Constraint Implementation Guidelines are required and will communicate any updates through normal industry channels.

The reclassification requirements for PEC was discussed at the Power System Security working group in 2025. It was agreed that no changes were going to be made to the framework. The new transmission lines for PEC would be assessed according to the current framework much like the addition of any other new transmission lines in the NEM.