Waratah battery tests full grid-protection capability

Akaysha Energy has moved the Waratah Super Battery closer to full grid-protection service in New South Wales after the 850MW/1,680MWh installation returned to its rated power output and subsequently discharged at a level consistent with testing its complete System Integrity Protection Scheme obligation.

Five-minute dispatch data recorded the battery at 850MW on 7 September, the first time it had reached its full power rating since a high-voltage transformer failure constrained operation last year. Two days later, the project discharged at 701MW, closely matching the 700MW continuous active-power level specified for its contracted SIPS service.

The events are commissioning milestones rather than confirmation that every contractual test has been completed. Akaysha had previously said full 700MW SIPS service would follow the return of High Voltage Transformer 3 and restoration of Waratah’s complete 850MW/1,680MWh capability, making the September output tests an important indication that the required electrical capacity is again available.

Waratah spent much of the past year below its intended power rating following failure of HVT3 in October 2025. The fault caused extensive winding damage and an overpressure event, while a second transformer was also taken out of service temporarily as a precaution.

Akaysha restored High Voltage Transformer 2 during the first half of 2026, allowing the battery to return to 700MW of power and its full 1,680MWh energy capacity in June. At that stage, however, only 350MW remained committed to the SIPS service, with the additional 350MW available for participation in the National Electricity Market while HVT3 replacement work continued.

The recovery illustrates how the operating capability of a large battery project depends on considerably more than its cells and inverter fleet. Waratah uses high-voltage transformers, switchgear, protection, controls, communications, auxiliary equipment, and transmission interfaces to convert stored energy into a dependable grid service.

A battery can retain its installed megawatt-hour capacity while losing much of its usable export capability if the high-voltage equipment connecting it to the network is unavailable. Transformer lead times make that vulnerability particularly significant because specialist replacement units cannot always be sourced on the same timetable as modular battery equipment.

Waratah’s main system role also differs from conventional battery arbitrage. The project was developed as part of a System Integrity Protection Scheme intended to increase the secure transfer capability of existing transmission infrastructure serving Sydney, Newcastle, and Wollongong.

Transgrid’s SIPS control system monitors 36 transmission lines in real time. When defined network conditions occur, the scheme can instruct Waratah to inject stored energy while paired generators reduce output, changing power flows quickly enough to prevent a contingency from developing into a wider transmission constraint.

The wider programme incorporates control equipment across 19 locations, upgrades at 22 substations, and work on four existing transmission lines. Its purpose is to allow more power to move through the network securely while longer-term transmission reinforcement is developed.

That makes Waratah a protection and control asset as much as an energy-storage plant. The useful output is not simply 850MW available for merchant dispatch, but a predefined response delivered at the speed and reliability required by a transmission security scheme.

EnergyCo specifies a guaranteed SIPS service of at least 700MW of continuous active power and 1,400MWh of usable energy. The installed battery is larger, at 850MW/1,680MWh, leaving capacity above the contracted protection requirement available for other market activity when operating conditions permit.

The oversized design gives Akaysha a commercial resource around the network-security obligation, but it also places considerable importance on state-of-charge management. A battery reserved for emergency injection has to retain enough stored energy to fulfil that service even when other wholesale or ancillary markets offer attractive dispatch opportunities.

Controls therefore have to coordinate commercial operation with the protected network requirement. State of charge, inverter availability, transformer status, transmission conditions, reserve requirements, and market dispatch all affect how much of the physical plant can be committed elsewhere without compromising the SIPS service.

The project occupies the former Munmorah coal-fired power station site, using established energy-industry land and transmission geography after the original thermal plant closed. Battery construction began in 2023, and the first 350MW/700MWh entered interim SIPS operation in August 2025.

Transformer failure subsequently stretched what had already been a technically complex commissioning programme. The experience is relevant to an international storage market increasingly focused on gigawatt-hour battery orders while high-voltage plant, network studies, protection integration, and specialist commissioning resources remain capable of setting the real delivery pace.

Reaching 850MW again demonstrates that Waratah can recover its full rated power following the failure, while the 701MW discharge provides evidence consistent with testing the complete contracted protection level. Neither observation removes the need for formal commissioning and service acceptance.

The next material milestone is therefore operational confirmation that the full 700MW SIPS obligation is continuously available under its contracted conditions. At that point, Waratah’s significance will lie less in holding another battery output record than in proving that a very large inverter-based storage plant can be integrated directly into the protection strategy of a transmission network.