Victoria’s AusNet Services owns and operates approximately $11 billion of electricity and gas distribution assets that connect into more than 1.3 million Victorian homes and businesses. But like many operators is keen to explore the ability to manage peak demand with the potential to defer investment in network upgrades.
Back in 2013 AusNet began investigating GESS, and chose to trial the technology. Following a competitive tender process, they awarded the contract to design, construct and deliver a GESS to a consortium led by ABB Australia and Samsung SDI, with ABB in Australia providing the integration technology and design and Samsung SDI taking the role of battery supplier.
Situated in the northern suburbs of Melbourne at an end-of-line distribution feeder in an industrial estate, the GESS is installed in a number of transportable shipping containers and transportable skids.
It consists of a 1 MWh 1C lithium battery system which interfaces to the microgrid through ‘the heart of the GESS’, a 1 MVA PowerStoreTM (an inverter-coupled energy storage system system which interfaces the Samsung lithium battery energy storage system to the grid), a 1 MVA diesel generator, a 3 MVA three-winding transformer and a SF6 gas-circuit breaker-based ring main unit with associated power protection systems.
Lithium-ion based batteries were used because of their high energy density and power ratings. The 1 MWh 1C batteries are capable of symmetric charge and discharge ratings of +/- 1 MW, and can transition from charge to discharge very quickly, allowing for robust system operation. They have a wide depth of discharge range of 3 percent to 100 percent and a known and predictable degradation of the state of health that allows for the total capacity of the GESS at end-of-life to be guaranteed. The batteries are installed in modular trays allowing for replacement of any single tray of cells without the need for extensive servicing.
Through the installation and commissioning process a full set of site acceptance tests were conducted to demonstrate GESS capabilities with respect to power system supply and stability, islanding and reconnection to the larger grid and management of the various system components ie passive and proportional load sharing between the PowerStore, battery management and charging.
Commissioned in December 2014, the system is nearing the end of a two-year trial to explore the benefits to peak demand management, power system quality and network investment deferral that large-scale, grid-connected energy systems can provide.
Signs are promising: the capabilities of the system demonstrated to date show promise for future microgrid applications.