How to be fire-ready in an unpredictable world (Part 2)
Extended impacts of bushfires for the energy system
This is the second in a two-part series on bushfires in Australia. In the first instalment, we looked at the history of bushfire in Australia and management strategies used to control the spread and limit the damage caused by bushfires. We looked at advances in bushfire forecasting, and the impacts of forecasts on emergency-response management. In this instalment, we will look at the impacts of bushfires beyond the immediate destructive burning, with a particular focus on energy – its generation, transmission, and distribution – and efforts to build energy systems that cause fewer bushfires and suffer less from bushfires that do occur.
With extreme weather events becoming more common, what are the broader impacts and side effects of bushfires on our built environment and on our ability to provide power for communities? We spoke with Dr Rohan Clarke about imagery technologies and their role in building a robust distribution network. We also spoke with Dr Tony Marxsen, Dr Simon Dunstall, Dr Reza Razzaghi and Prof. Jacek Jasieniak about powerlines as a bushfire ignition source, about locating the highest risk networks in Victoria and about energy access in times of bushfire.
Dr Tony Marxsen, Chairman of the Monash Grid Innovation Hub “the concept of sustainability is providing a liveable community, having our environment and people in their everyday lives and quality of life supported. And part of that is public safety”. About 90% of the fire deaths during the Black Saturday Bushfires (2009) were caused by fires resulting from ignition sources related to powerlines. For him, the Government investment in powerline bushfire safety since Black Saturday is evidence based and economically efficient. “Any day of strong wind in Victoria usually has not less than twenty and often more than a hundred powerline faults across the State. There will always be powerline faults, the trick is to prevent them starting fires – and the new technology is making serious inroads in this.”
Victoria’ electricity network owners are legally obliged to manage powerlines and adjacent vegetation to reduce bushfire risks. Powerline settings are changed before the fire season around November-December to reduce powerline bushfire risks and there is some cost to supply reliability in doing this. With climate change, it’s harder to provide both fire safety and supply reliability, as the duration of fire seasons extend with each passing year. When a fault happens on a powerline, what technology best prevents fires from starting? To be able to answer this, we need to consider the different types of powerlines between your home and the electricity generators, and the voltages at which they operate. Tony outlines this for us. Victoria has two powerline types known to cause serious fires: Single Wire Earth Return (SWER; 12700 volts; 30,000 km of lines in rural Victoria) and Polyphase (two-wire or three-wire configurations, 22,000 volts, 50,000 kilometres of lines in rural Victoria). Rural SWER lines and polyphase lines have fundamentally different structures, so fire-safety solutions for one line-type don’t necessarily work for the other.
The cheap and reliable SWER powerlines supply farmhouses, pumping stations, shearing sheds out in the bush. Current goes to the customer on a single wire and returns to the source substation through the earth. Ten to twenty per cent of the bushfires ignited by powerlines in Victoria are from faults on SWER lines, largely when broken lines fall and arc current directly into the ground or vegetation they fall across. Technology options for SWER lines include smart Automatic Circuit Reclosers (ACRs) and Early Fault Detection (EFD), or conventional undergrounding or insulation and the costs and benefits of each vary widely. Tony explained that research is also underway both here and in California into new methods of detecting falling SWER powerlines in time to disconnect them before they hit the ground.
In contrast to SWER lines, polyphase powerlines supply areas with large numbers of customers, largely in urban and suburban areas. One option for polyphase lines is ‘REFCLs’ – automated systems that reduce the voltage carried by a faulty line, with a response time of about a twentieth of a second. REFCLs can protect two and three-wire polyphase powerlines. Victoria is three years into a seven-year roll-out of REFCLs across its 45 highest risk networks. Results to date confirm the research findings: REFCLs are effective in prevention of the most common types of fire-starting powerline faults on polyphase powerlines, even in Code Red conditions as occurred on the 21st of November 2019.
Dr Simon Dunstall, Research Director of the Decision Sciences Program (Data61, CSIRO), mentions “Determining where the highest risk networks were in Victoria was a mathematical modelling and data analytics challenge that was funded by the Victorian Government and led by CSIRO Data61. With invaluable assistance from industry experts including Dr Tony Marxsen, the CSIRO team set out to quantify how well REFCL might perform in bushfire risk reduction across the range of weather and vegetation conditions in Victoria, and to combine this with fire simulation modelling to identify the areas of highest risk, and of highest risk reduction potential through REFCL. The result was targeted infrastructure changes including REFCL in the 45 highest risk networks. These changes are expected to reduce Victoria’s total powerline bushfire risk by 60% by April 2023, and require capital funding that is around 2% of what would be ultimately required if Victoria followed the Bushfires Royal Commission (2011) Recommendation 27 that all bare wire overhead powerlines with bushfire risk in the state should be progressively replaced by underground cables or covered conductors".
Dr Reza Razzaghi, Lecturer with the Department of Electrical and Computer Systems Engineering, adds “Victoria’s traditional network grounding method is via a resistor and powerline faults can produce a thousand amps of current into the ground. The REFCL system uses resonant grounding which reduces this to less than five amps. To reduce it even further, to less than half an amp which is the limit for fires to start, they displace the neutral voltage to collapse the voltage on the fallen wire, leading to a very low current from the powerline into the local environment. At the same time, the displacement of the neutral voltage increases the voltage on the two un-faulted phases. Despite all the benefits of REFCLs in minimising fire risks, introducing REFCLs to power distribution networks can add additional complexity to fault location procedures as low fault currents due to REFCLs do not produce physical evidence, not do they trigger existing fault location devices such as Fault Passage Indicators (FPIs). Without information from FPIs, the fault location process requires a visual inspection along the entire length of the feeder to locate the fault and sometimes even then, the fault cannot be found. This is very time-consuming, leading to longer power outages during high fire-risk weather. New fault location techniques are required to complement REFCLs.
In other parts of the world, the powerlines mix is different. Tony mentions the example of California, where it is not legal to construct SWER powerlines, so all powerlines are polyphase, with four-wire high voltage powerlines being the most common type. REFCLs cannot do anything to cut fire-risk from faults on high-voltage four-wire powerlines. The fourth wire is a neutral that is directly connected to earth at hundreds of locations across the network. So, the neutral voltage cannot be manipulated to control the fault current and stop fires. These networks can have currents into the ground of twenty thousand amps or more.
Providing power to communities in the bush is an essential service that comes with the risk of having potential ignition sources in bushfire prone areas. In Victoria alone, there are about 80,000 kilometres of rural power lines, so being able to inspect networks to ensure safe and reliable supply of electricity to consumers is a must. Could drones with high resolution imagery, thermal cameras and Light Detection and Ranging (LiDAR) technology be used as part of maintenance programs, or for damage and recovery actions after fire or floods? Could they help to assess powerlines structures and detect points of failure? Victoria’s network owners are already investing heavily in LiDAR technology to confirm wire-to-vegetation and wire-to-wire clearances comply with standards. For Dr Rohan Clarke, Ecologist and Conservation Biologist at Monash and director of the Drone Discovery Platform for researchers, unmanned aerial vehicles (UAVs) can bridge the gap between ground and satellite observations, whilst minimising risks to workers. Rohan was sent early this year on a threatened fauna rescue mission ahead of an active fire, and for him, “there is real potential for drones to inform emergency response actions, undertake damage assessments and inform recovery actions (for communities and the environment). However, development of tools and protocols to facilitate the safe use of drones on fire grounds (while manned aircraft are being used to fight the fires) is an element that requires innovative solutions”.
During bushfires, electricity connections can be regionally disrupted. Traditionally, this disruption has been caused by wood pole powerlines being burned to the ground. However, new issues are emerging. Since October last year, cities in south-eastern Australia and in New Zealand have been intermittently covered with smoke, reducing visibility and a solar farm near Canberra was damaged. Could smoke haze impact solar energy production if it became more common in Australia? Prof. Jacek Jasieniak mentions that “solar efficiency will drop under smoke or haze, so what we need is a distributed form of production where the impact of very regional changes in solar efficiency is averaged across the electrical grid. The deposition of ash or dust on solar panels will also reduce the amount of light impinging on the panel, reducing power production. Further complementing solar cells with appropriately spaced wind farms can reduce regional impact. Local towns need back-up systems to provide electricity, which are typically in the form of expensive diesel generators. As energy storage technology becomes cheaper, such conventional backup systems will likely be displaced by batteries or other forms of energy storage. The recent fires also threw a new challenge into sharp relief – preservation of vital communications to help communities survive fire threats when hundreds of mobile phone towers run out of their limited battery power. Use of defense forces to drop satellite phones into isolated communities is a partial solution at best and new approaches are currently being sought to alleviate this problem.
Dr Rohan Clarke is the Director of Science for the Monash University Drone Discovery Platform, and an Ecologist and Conservation Biologist in the School of Biological Sciences. His research focuses on the ecology of Australian birds, especially threatened species, and the field-application of cutting-edge technology to improve conservation management.
Dr Simon Dunstall is the Victorian Lab Leader for CSIRO Data61 and co-director of the Analytics and Decision Sciences program. Simon is currently working with Monash Grid Innovation Hub researcher from the Faculty of IT’s Data Science and AI researchers A/Prof Ariel Liebman, Dr Edward Lam, and Prof Peter Stuckey on large scale power system investment planning and optimisation for a renewable future. He is also co-director of the Analytics and Decision Sciences program. Simon has been the principal investigator in numerous research project teams looking at supply chain and logistics, service delivery systems, electricity infrastructure and natural hazards (mainly bushfires) during an R&D career spanning two decades. He is the current National President of the Australian Society for Operations Research, and co-supervises PhD students at Monash and Melbourne Universities on energy and optimisation topics. Simon is part of the group that has been developing the Spark bushfire simulation toolkit (https://research.csiro.au/spark/), as well as Swift (https://research.csiro.au/swift/) for the dynamic modelling of coastal inundation and flash flooding.
Prof. Jacek Jasieniak, Materials Science & Engineering, Director of the Monash Energy Institute. Jacek is interested in developing nanoscale materials and applying these to energy technologies that can be commercialized at a lower cost and greater supply renewable energy across the world. He has technical expertise in a solar cell, energy storage and light emitting device development.
Dr Tony Marxsen has an electrical engineering degree and PhD from Monash University. During his career in the Victorian electricity industry, he worked in all aspects of electricity transmission and distribution engineering and business management. Tony was lead researcher in Victoria’s R&D program to cut bushfire risk associated with rural powerlines and remains involved in oversight of the roll-out of Rapid Earth Fault Current Limiters to the State’s highest risk networks and modern ACRs to all of Victoria’s SWER networks. Tony is Chairman of IND Technology Pty Ltd and plays an active role in the development of Early Fault Detection technology which is now installed in Australia, China and the US.
Dr Reza Razzaghi is a Lecturer with the Department of Electrical and Computer Systems Engineering. His research expertise is in power system protection and electromagnetic transients in power networks. Reza has been the recipient of multiple prestigious awards including the 2019 Best Paper Award of the IEEE Transactions on EMC and the 2013 Basil Papadias Award from the IEEE Power and Energy Society.
For further information:
- Bushfires in general
- Powerline Bushfire Safety Short Course. Monash University and Electric Energy Society of Australia (EESA) offered a 4-day professional development short course (24-28 June 2019) for all Network Engineers and university researchers/students to gain essential knowledge and practical skill-sets to ensure Powerline Bushfire Safety. The course was developed in response to participants need of such a course at the National Bushfire Mitigation Forum (Sydney, 1 November 2018). The course, sponsored by Dr Tony Marxsen, involved information delivery by industry engineers in Victoria’s powerline bushfire safety program and leaders of Ignition research projects, interactive discussion sessions, open Q&A forums, and hands-on use of simulation tools to explore varying simulations of network faults likely to cause fires. There was also an option to attend a two-hour workshop on network earthing options. Dr Tony Marxsen who presented Victoria’s ground-breaking ignition research to the course, mentioned that it was great to see other Australian States (NSW and Queensland) participating as well as Southern California Edison. “There is an informal national group of engineers involved in fire safety. The Powerline Bushfire safety course was proposed and seen as a very good idea. Our 2019 course received fifteen participants (from network businesses, manufacturers, consultants) who had the opportunity to enjoy the expertise from presenters from Monash, CSIRO and the Victorian electricity industry.Lots of people were disappointed they didn’t know about the course. We will consider running it again in 2021”.
- Drone Discovery Platform for researchers
- The PBST final report and the 2015 Regulatory Impact Statement (RIS)
PRECISION by NVN (April 3, 2020, 12:25 p.m.): an earlier version of this article had a a simplified statement about the Bushfires Royal Commission (2011) Recommendation 27 that all bare wire overhead powerlines with bushfire risk in the state should be replaced by underground cables. The replacement should be progressive and by underground cables or covered conductors.