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GMA Garnet Microgrid

At Port Gregory in the Mid West, Advanced Energy Resources (AER) built a $11.2 million microgrid to supply GMA Garnet's nearby mine. It aims to provide up to 70 per cent of the mine's power needs.

Balance was to design, supply and install a 4.4MVA / 586kWh BESS and microgrid controller which enables the system to electrically be decoupled from Western Power, thus only use renewable energy for operations.

GMA Garnet Mine Site. Port Gregory WA
AER GMA Garnet Microgrid
2.5MW wind farm, 1MW solar farm and a 2MW/0.5MWh battery.
Under Construction
GMA Garnet Microgrid

This form of microgrid has not previously been utilised in Australia and specific similar examples cannot be found internationally.



Balance developed an innovative microgrid controller for the GMA Garnet mine site to enable both on-grid and off- grid functionality via a back-to-back inverter topology. The approach electrically isolates the grid from the mine power supply and allows additional renewable generation to be connected and not assessed by network utility for interconnection compliance.

The topology involves the use of two inverters in a back-to-back configuration coupled across a battery. The grid side inverter is controlled in a grid following mode, which will ensure network transients are maintained for all import and export requirements.

Arena chief executive Darren Miller said "customers at the fringe of power grids often suffered network outages, so microgrids with batteries could improve reliability"

"This grid connection design overcomes challenges associated with connections to weak grids, providing backup power, and facilitating high penetrations of customer-side renewable generation.

"Effectively, this approach allows the solar and wind to operate in a microgrid with the battery and inverters, which avoided the need to upgrade the network."

This novel solution allows the expansion of renewable generation on the fringe of utility networks near load centers. It also has the ability to support transmission and distribution feeders by improving local power quality and reducing peak demand. This will substantially improve grid robustness and undoubtedly be of benefit to all electricity users.



The back to back topology provides the following advantages to the utility;

  • Facilitates more renewable generation to be connected at the fringes of the network
  • Significantly stabalises the voltage profile on the remote feeders
  • Allows controlled and smoothed renewable generation into the network
  • Provides electrical isolation from the network, simplifying technical compliance issues

Advantages for the mine

  • Provides a short term UPS functionality for the client
  • UPS time is extended as possible by renewables
  • Increase power quality (Voltage)
  • Provide immunity from localised network issues