Mitigating the risk of fire associated with certain electricity assets is vital in Australia’s bushfire prone climate. However, traditional methods of surveying large electricity networks are costly and time­consuming. Recently, Geomatic Technologies completed works surveying parts of the Powercor and AusNet Services electricity networks in Victoria using an innovative method that greatly reduced the time and expenditure required.

Reducing the risk of fire 

The award­winning Bushfire Safety Clearance Program was undertaken by Geomatic Technologies. The program employed a combination of positioning technology, LiDAR scanning and image processing to measure conductor clearances and identify sections of the networks requiring remedial action to prevent poorly spaced conductors potentially sparking fires.

Following the Black Saturday bushfires in February 2009 and subsequent inquiry, the Victorian Bushfire Royal Commission made 67 recommendations to reduce the likelihood of a similar disaster recurring. These included a recommendation that spreaders be fitted to any electricity lines with a history of clashing or the potential to do so.

Conductor spacing is an important aspect of electricity asset management and bushfire mitigation due to the fire risk posed when lines are too close to each other, or to vegetation, the ground or other objects.

“During windy and hot conditions, conductors may sag and make contact causing ‘arcing’, which significantly increases the risk of a fire ignition,” said Mathew Croft, Business Manager (Power and Telco) at Geomatic Technologies.

“Therefore, maintaining safe conductor clearances on electrical networks is important for bushfire mitigation and, ultimately, public safety.”

Following the adoption of the Royal Commission’s recommendations by the Victorian Government, Victorian electricity utilities were required to assess conductor separation throughout their networks. Recognising the need for a more efficient method of measuring powerline clearances throughout their large networks, AusNet Services and Powercor engaged Geomatic Technologies (GT) to develop a custom solution.

Finding a better way

The Bushfire Safety Clearance Project required the integration of multiple sensors, as well as a custom software application to process and model the conductor infrastructure to meet the Australian distribution conductor modelling standard.

Having undertaken infrastructure clearance studies using LiDAR in the rail industry for over a decade, GT’s team was experienced in developing custom solutions to meet complex compliance requirements of this type.

Accurately and effectively measuring conductor clearances throughout the Powercor and AusNet Services networks and identifying potential clearance issues required various different data types to be collected. These comprised:

  • LiDAR data (a surveying technology using pulsed laser to measure distances, also known as 3D laser scanning)
  • GPS coordinates
  • 3D Panoramic street­level imagery
  • Inertial data (mobile survey only)
  • Weather data – air temperature, wind speed, wind direction.

“The previous method of collecting this data was via a traditional survey team,” said Mr Croft.

“The surveyors would normally use a total station to collect measurements at the pole and several points along the conductor. This method would normally only achieve a handful of points on each conductor and beneath each span. Using LiDAR we can generate a complete point cloud of the entire span with hundreds of measurements along each conductor.

“Due to the number of spans required to be surveyed by the regulator (Energy Safety Victoria), traditional survey methodology was not practical from cost and time perspective.”

Surveying expansive networks efficiently

Throughout the project, GT surveyed large sections of the electricity networks, requiring effective management of the survey teams to ensure the works were completed as efficiently as possible.

For instance, the AusNet Services conductor clearance survey consisted of approximately 15,000 spans, which were progressively completed in successive stages.

“Each stage is broken up into general regions and then split into sites of approximately 100 contiguous spans or less,” said Mr Croft.

To efficiently survey such large spans GT employed its GT AIMS 3D (Asset Inspection Management System), which incorporates 3D panoramic imagery and LiDAR sensors, mounted on a survey vehicle.

“The mobile survey can capture many spans in fast succession – it takes as long as it does to drive along the length of the span,” said Mr Croft.

“If the span is not traversable by vehicle, then the terrestrial survey method is required, where GT surveyors will use a Riegl VZ400 3D laser scanner to generate a point cloud to fill in the gaps that the mobile vehicle cannot traverse.”

GIS technology played a large role in managing the deployment of the survey teams.

“In terms of managing the two teams and the spans required to be surveyed, we heavily utilised GIS to manage the status of every required span. GT used AIMS Karta, its in­house field capture software, to manage the field teams’ progress.

“The mobile field crew would mark off which spans were captured and which spans would require the terrestrial survey team to visit. The terrestrial survey crew would then mark off which spans they had captured. All of this data was sent back to a server, which could be viewed from the office. Each time the field crews would sync the data the office team would get an update on which spans had been captured and which spans remained.”

Precision clearance measurement

As well as this survey method being significantly quicker and cheaper than traditional methods, it also enables very precise clearance measurements, the accuracy of which were verified by AusNet Services through a separate auditing exercise.

Once the collected data was processed, special software, GT AIMS Catenary, was used to manage desktop­based data analysis, feature classification and catenary modelling.

This software integrates 3D imagery with LiDAR, conductor loading information and weather data, and then automatically reports any clearance violations. Additionally, it also allows equipment to be mapped and asset condition to be assessed.

While the inspections were primarily focused on clearances between conductor-­to-­conductor, conductor-­to­ground and conductor-to-­structure, GT also analysed conductor-­to-­vegetation clearances.

As the system does not rely on any existing engineering design packages, it could be tailored to the specific requirements of the application.

Overcoming the challenges of the Victorian landscape 

The Victorian landscape posed an array of different challenges that had to be overcome by the survey teams. These challenges related not only to the variable terrain and requirement for off­road driving, but also extreme hot or cold conditions, landowners, environmental concerns, logistics, livestock and wildlife.

“The mobile field team were almost constantly challenged by terrain,” said Mr Croft.

“The vast majority of high bushfire risk spans are located in rural areas, which are often traversing farm paddocks. Spans cross creeks, rivers and gullies really well – 4WD vehicles don’t. AusNet Services distribution area covers a lot of hilly terrain and a lot of farmland. All field crew members were trained in correct and safe 4WD operation and vehicle recovery.

“During the warmer months the team were faced with dangerous fire conditions and were instructed to avoid driving on private property during days of severe, extreme or catastrophic fire danger days or days of total fire ban.

“Driving from farm paddock to farm paddock added an environmental complexity, where crews had to maintain vehicle cleanliness standards and ensure that mud or seeds were not transported from farm to farm,” said Mr Croft.

“The terrestrial team were often carrying survey equipment across the terrain that the mobile vehicle cannot drive on, and often involved hiking into inaccessible areas.

“Snakes, spiders, wasps, cattle and dogs were all various issues dealt with on a daily basis.”

At one stage the teams also needed to access the Hazelwood mine, requiring them to undergo the relevant site inductions before they could gain access.

Nevertheless, despite these obstacles, the surveys were completed well ahead of schedule.

“GT has been working through the stages since November 2012 with an end goal of completing all HBRA (High Bushfire Rated Area) spans by December 2015,” said Mr Croft.

“GT successfully reached this target in September 2015.”

A new benchmark in conductor separation assessment 

The success of the Bushfire Clearance Safety Program was recognised at the 2015 Victorian Spatial Excellence Awards, winning the Award for Innovation and Commercialisation.

The judges cited the innovative combination of technologies, as well as the efficiency, accuracy and cost­effectiveness of the project as the aspects which made it stand out and which “clearly establish it as an industry benchmark”.

This also puts the project in the running for the Asia Pacific Spatial Excellence Awards (APSEA).The benefits realised through GT’s custom clearance survey solution demonstrate a highly effective and efficient method of assessing condition across large networks. As a result it is likely that there will be a much larger uptake of similar solutions in the future to detect different network defects.

Mr Croft said, “Electrical utilities are faced with a continual challenge of reducing cost while maintaining network safely. GT envisages being able to assist network owners to reduce the cost of inspection and assess the network by enhancing our solution to be able to complete a ‘single pass’ with several sensors to capture data that can be used to determine various network defects, where traditional methods have required several visits via manual inspection ‘on foot’.”

All in all, the Bushfire Safety Clearance Project is a successful example of utilising technological innovation in a way which not only reduces expenditure, but also contributes to better asset management and has the potential to save property and lives.

Jessica Dickers is an experienced journalist, editor and content creator who is currently the Editor of Utility’s sister publication, Infrastructure. With a strong writing background, Jessica has experience in journalism, editing, print production, content marketing, event program creation, PR and editorial management. Her favourite part of her role as editor is collaborating with the sector to put together the best industry-leading content for the audience.

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