Australia’s energy market rule maker has introduced new technical standards for large inverter-based loads connecting to the National Electricity Market (NEM), including data centres, in a move intended to reduce the risk of large-scale disconnections during power system disturbances.
The Australian Energy Market Commission (AEMC) published its final determination and rule on 12 November, establishing a 30MW threshold for classifying a large inverter-based load (IBL). The definition is based on a combined nameplate rating of 30MW or more and applies to connections across both transmission and distribution networks.
The AEMC said the new framework responds to the growing number of large loads using power electronics, which can react rapidly to changes in electricity system conditions and interact dynamically with the grid. In some circumstances, these interactions can contribute to cascading disconnections, potentially resulting in significant load loss and wider supply disruptions.
The commission cited forecasts from the Australian Energy Market Operator (AEMO) projecting that data centre electricity consumption will increase around sevenfold over the next decade, from approximately 5TWh currently to 34TWh, lifting its share of operational demand from around 3 percent to 13 percent.
Under the final rule, large IBLs will be subject to new disturbance ride-through access standards requiring them to remain connected during specified voltage and frequency disturbances and meet performance requirements following those events. The standards include requirements for voltage ride-through and active power recovery, frequency ride-through, and limits on how protection systems operate following phase-angle shifts or successive faults.
The requirements are intended to reduce the risk of large loads disconnecting unnecessarily when the electricity system is under stress. The AEMC noted that data centres commonly use uninterruptible power supply (UPS) systems, which can allow them to switch to backup power during a disturbance without interrupting services to end users. However, the resulting disconnection from the grid can affect the balance of supply and demand and contribute to instability.
Instability-monitoring
The rule also introduces a new instability-monitoring access standard requiring large IBLs to detect and respond to specified forms of instability. Network service providers will be required to consider the potential combined impact of electrically proximate loads where their connection arrangements and intended operation indicate they should be assessed together.
AEMO will also be required to develop and maintain modelling guidelines for loads connecting under Schedule 5.3 of the National Electricity Rules, with requirements intended to be proportionate to the potential system impact of each connection.
The final rule clarifies that UPS systems commonly used by data centres are assessed under Schedule 5.3, rather than being inappropriately classified as bidirectional units under Schedule 5.2. It also harmonises the classification framework for inverter-based loads connecting to transmission and distribution networks.
The rule commenced on 12 November. A six-month grace period applies to certain connection applications that had progressed to an advanced stage before commencement, including those where technical requirements had been accepted and the network service provider was preparing an offer to connect. If an offer is not made before the grace period expires, the new standards will apply.
The determination is part of a broader AEMC data centre reform programme covering data centre contracting obligations, network augmentation costs, operational visibility and the connections process. Alongside the final rule, the commission has released a consultation paper on the operational integration and visibility of large inverter-based loads, seeking feedback on proposed measures including registration, real-time communications and monitoring requirements.