The rapid integration of variable renewable generation is transforming Australia’s energy network, and grid-forming inverters have an essential role to play in maintaining the stability of our power system.
Grid-forming inverter technology, also known as virtual synchronous machine (VSM) technology, has become well-established in the National Electricity Market (NEM). Specifications such as the Australian Energy Market Operator (AEMO) Voluntary Specification for grid-forming inverters – in combination with the technology’s capabilities and the recent reduction of its cost – have enabled the pathway for adoption. Many countries overseas are now looking to how Australia is adopting grid-forming inverter technology.
As the energy transformation gathers pace, more decentralised, or edge-of-grid, renewable energy plants need to connect to the grid and, at the same time large, centralised fossil fuel power plants are retiring – resulting in inherent instability in the power grid.
VVSMs emulate the behaviour of traditional synchronous generators, providing inertia and stability to the grid. In contrast to grid–following inverters – which are often used in combination with synchronous condensers – grid-forming inverters help prevent blackouts and ensure reliable power supply during disturbances or faults
As renewable energy sources such as solar and wind proliferate, VSMs enable seamless integration. They allow renewable inverters to operate in grid-forming mode, reducing reliance on fossil fuel-based synchronous generators.
Hitachi Energy’s VSM technology acts as a spinning reserve, ready to supply power during sudden demand spikes. In contingency events, VSMs can be the sole grid-forming reference, ensuring grid stability. By leveraging advanced power electronics, Hitachi Energy’s grid-forming energy storage systems offer inertia and system strength.
Collaboration for grid innovation
Hitachi Energy is working with utilities and industry to demonstrate the technical feasibility of grid-forming inverter technology in Australia and has constructed smaller grid-forming battery systems as financially viable references through additional value stacking.
Australia’s energy regulator investigated how grid-forming inverter technology could replace traditional synchronous condensers. The consultation process led by AEMO demonstrated how the industry can come together and agree on specifications and capabilities when introducing new technologies, cumulating in the publication of the AEMO Voluntary Specification for Grid-forming Inverters1.
These specifications provide guidance to stakeholders as the regulatory environment around grid-forming technology develops. This, combined with the technology’s capabilities and its cost coming down, have enabled the pathway for adoption in Australia and around the world.
Today, success is evident in the large number of grid-forming batteries being connected to the NEM in order to allow self-remediation and avoid high system strength charges. Additionally, grid-forming inverters with virtual synchronous machine capabilities have also led to a number of microgrid projects at the distribution level.
Dalrymple proves viability of grid-forming inverters
A breakthrough came in 2018 with the Dalrymple ESCRI-SA battery project, demonstrating how energy storage can strengthen the grid and improve reliability for the lower Yorke Peninsula. The ElectraNet project, part-funded by the Australian Renewable Energy Agency (ARENA), was the first transmission grid-connected battery in the NEM that provides both regulated and competitive market services.
ElectraNet delivered an extensive knowledge-sharing program to provide unprecedented transparency for a grid-scale BESS. At that time, the battery was the first and only large-scale grid-forming energy storage system in Australia’s grid and the largest such system in the world. 2
Innovation for a sustainable energy future
Through advanced power electronics, grid-forming energy storage systems can provide inertia and system strength, and they are quickly replacing grid-following solar and battery energy storage inverters. As Australia is pushing to meet its net zero commitments and renewable energy targets, these systems can further unlock revenue streams to support the economic viability of a project and address the technical challenges.
References
1. AEMO Voluntary Specification for Grid-forming Inverters, May 2023 gfm-voluntary-spec.pdf
2. ESCRI-SA Battery Energy Storage Final Report – Australian Renewable Energy Agency (ARENA)
