With more people than ever hooked up to solar, and batteries set to grow, a microgrid could make perfect sense for a regional city like Cairns in Queensland’s Far North, especially as a back-up after a cyclone.

The threat of cyclone impact is always a looming one each summer in the northern half of coastal Australia, so network resilience is thinking ahead that’s bound to interest many resident North and Far North Queenslanders.

University of Queensland Masters student Nick Beere undertook exclusive research for Ergon Energy about microgrids using the tropical northern tourist mecca of Cairns as the basis for the six-month study. 

Microgrids are already prevalent throughout the world, but are most commonly used for small, critical loads such as hospitals, university campuses or even military bases. But talk is increasing about using microgrids for new housing and commercial estates, or even small country towns.

Nick looked at what would happen in a hypothetical situation of the transmission network south of Cairns being lost and only local feeder level generation was included. For the purposes of his study he assumed everything from the sub-transmission system upwards had lost supply or was unavailable due to failure, natural disaster or other impact.

He then simulated them for different times of the year to characterise different load and weather events as they would result in different operating conditions for the local network.

In the case study, he found there was a large drop in fault current, which meant one of the existing protection devices would not operate, and so Ergon would need dynamic protection settings that could change based on the operating condition they were in.

Protection systems and their finely-tuned settings are critical in safely running electricity networks. Faults or malfunctions with network equipment can mean more than just an annoying power interruption – they can cause hugely expensive damage or risk to human life if protection systems don’t operate correctly.

“In terms of costs, the study found the case doesn’t stack up for Ergon presently, but in the case of restoration response, such as after a cyclone, there is a positive social value and broader benefits to the community,” Network Strategy and Policy Engineer Don McPhail said.

This work was born out of Ergon’s Microgrid Strategy, produced in 2014.

“Going forward we are looking to continue to work on the recommendations in the strategy document, as well as a number of the recommendations that Nick has made in his thesis,” Don said. “His methodology and the insights from its application have been valuable in starting us down this journey, and initiating a number of conversations or covering off some concerns, like regulatory, legal and protection system related factors.”