Mandatory asset inspection is crucial for utilities. Employees are often challenged with hard-to-access areas, heights or risky terrains. The traditional examination methods such as on-foot patrols, helicopters or industrial climbers are costly and time-consuming. Read more to learn how Axpo tackled these challenges by using the latest P3 Payload sensor technology from Phase One and LINIA’s drone software for automated power line inspection.
Ensuring supply and security
We rely on our nation’s power supply. We like knowing that when we flip a switch or need to charge our phone battery, the power is there to make it work the way that we expect it to. Delivering that power to each house is several thousand kilometers of power lines that make up the backbone of our power supply. With power lines there is a risk of failure. For the power grid to keep supplying consistent power, companies must regularly check the power lines to ensure that there are no damaged areas that could cause failure in the future.
While these inspections were previously done manually by special teams by visual inspection, this meant that employees were required to work at heights and in dangerous circumstances. In addition, manual inspection also not only resulted in huge logistical efforts using cherry pickers and cranes, created work grounding and periods of going off grid, it also posed a great risk of occupational hazards.
Thankfully, one way to make powerline inspections safer and more efficient is the use of drones, high-resolution sensors and software for drone automation.
Axpo – Providing climate-friendly power for Switzerland and beyond
Together with its partners, Axpo operates more than 100 power plants. Their climate-friendly Swiss electricity mix features reduced CO2 emissions and consists of hydropower, biomass, solar, wind and nuclear energy. They are not only the largest producer of hydropower but also the largest producer of renewable energy in Switzerland, supplying their customers with up to 3200 MW of capacity via a 2200-kilometers distribution line (110, 50 and 16 kilovolts).
Axpo has over 5000 employees worldwide, over 100 years of experience and operates in more than 30 countries.
Taking the next step for a faster, safer and more efficient inspection
The Axpo distribution lines of 2,200 kilometers with 7,500 masts, results in a significant effort to regularly inspect all parts of the vast grid to ensure stability. In addition to masts, isolators and rooftops, inspection tasks also include bird protection hoods, wires and screws.
Before purchasing the Phase One P3 Payload with the iXM100 sensor, Axpo used common drones with standard sensors for asset inspection. This provided several down-sites including time needed, unsafe distances to powerlines and masts as well as insufficient data quality.
For a ground sampling distance of 0.5mm/px they sometimes had to fly up to 3m from the systems, which poses a great safety risk. In addition, 6 or more images were needed to be able to fully inspect the concrete poles. For much larger TSO systems, at least twice the number of images was needed for a full inspection while also the increased safety distances required were too large to achieve the needed GSD of 1.0mm/px.
How Phase One’s P3 can help to streamline effort, increase quality and safety
With the Phase One solution, Axpo can easily tackle these challenges, as they only need a maximum of four images to show the mast completely, while also getting a better and more detailed shot due to the high-resolution iXM 100MP camera, even though they can fly at greatly increased and much safer distance. The distance gained without losing the information on the image (even more information is more likely) allows us to use standardized flight patterns and thus increase our productivity and quality.
The P3’s integrated the Laser Range Finder, allows Axpo to always exactly determine distances and adjust if necessary, to ensure that the focus remains the same – even with lattice masts, where the mast has openings due to the lattice structure.
With the iXM 100MP, Axpo can now generate high-resolution and detailed photos, with no loss of information when using the zoom function. These enable off-flight control and can also be viewed again at a later point in time, enabling a full long-term documentation of the condition and development of the grid over time and offering in-depth insights into operational data.
Another benefit is that the service – flight and evaluation – can now be carried out completely in-house, without having to involve a third party, again adding to efficiency and cost savings.
While initially handling large image data posed a challenge, Axpo decided on new approaches for data storage, display and image processing, further streamlining the workflow and efficiency.
Drone application LINIAair enables a fast, structured and reliable data acquisition process
A drone pilot can easily capture data of a single power line tower. The challenge rises, when 1000 or more towers need to be inspected in a short period of time. How do you ensure a consistent, safe and well-structured data acquisition?
LINIA automatically calculates flight routes, based on digital line models (Figure 1). The drone app LINIAair is designed to facilitate the inspection process smoothly (Figure 2). A short instruction for drone pilots is sufficient to simplify the data capture process. On site, pilots select the corresponding flight routes on the drone app and press start. The drone, equipped with Phase One’s P3 is automatically capturing data until the battery is low. Even the lens-focus is automated which guarantees that there are no blurred photos. During the flight, the pilots’ main task is to supervise the drone and the surrounding, in case of emergency. One pilot and one drone are sufficient to do the job. However, for safety reasons, line inspections are often performed with two persons. In this case, to raise productivity and when the topology allows is, the team can dislocate during the flight, with one person supervising the drone and the second one replace the car.
Figure 1: Example of a flight routes (red/white) and a digital tower model (blue). The red pyramids indicate the direction and field of vision of the camera
One advantage of automated drone flights is the speed aspect. Depending on the size of the tower, it takes between 3 – 5 minutes to capture 20-30 images of a single TSO-tower (220/380kV) or 2-3 minutes for a DSO-tower (110kV). Within a single flight of 15-20 minutes airtime, the photos of 3 TSO-towers or 4-6 DSO-towers are acquired.
Lorenzo Arizzoli-Bulato, Founder of LINIA states: “The daily capacity is limited by the time a pilot needs to relocate along the line. Last year, I once inspected 80 132-kV-towers in a single day. That was in very flat and easy terrain, though. In Alpine terrain, the daily output is around 20 TSO towers per day. In flat areas between 25 – 40 towers per day. This are good numbers, considering manual drone inspection takes up to 20 minutes for a single tower. But still, there is much more potential in the future, when drones have longer flight capabilities and the technology supports better BVLOS flights.”
Figure 2: LINIAair Screenshot. The main screen shows the drones FPV-cam. Bottom left: PhaseOne vision. Bottom right: map with flight route. The app allows to toggle between different views.
But speed is not the only advantage of automated line inspection.
Repeatability: The Flight-routes are repeatable in new inspection-cycles. The images can be compared very well, because of the same position and perspective. This enables predictive maintenance.
Structure: There is a standard structure, on how the images are acquired. This structure provides full coverage of the whole tower and makes all imagery look similar, which is helpful for further data analysis.
Linking between photos and objects: The flight routes are based on digital line models. That connection is used to link objects, such as insulators directly with photos. To be more specific: Each photo gets renamed and consists of information about line, tower, crossarm and perspective (Figure 3). This meta-data is used for further processing and enables proper data storage.
Safety: Assessing the distance between the line and the drone is very challenging, from a far position. There is always the possibility of human failure, when flying the drones manually. LINIAair is designed for line men, which means, basic drone knowledge is sufficient to execute safe drone operations. Automated and approved flight routes minimize the risk of mishandling the drone and raise the overall flight safety.
Figure 3: Metainformation included in the photo-name: line/tower-number, crossarm identifier, perspective.
Summarising the benefits
With the P3 and the iXM 100MP sensor, efficiency is at the forefront of Axpo’s activities. They can now take a series of high-quality pictures from different angles detecting technical malfunctions and determine the precise GPS location of the assets enabling them to perform a predictive asset assessment, minimizing maintenance costs and service disruptions.
Faster restoration of power supply
Axpo can now significantly reduce the time to identify the fault and restore power in case of outages compared to traditional methods. Utilities can clearly see the problem via provided imagery data, pinpoint its location using GPS and start working on the resolution.
Significant cost reduction
Minimizing the number of site visits by trained professionals and saving cost preventing repairs of unwanted shut-downs, making inspections significantly faster and much more cost-effective.
Improved assets management
Better observation, detailed and long-term documentation and timely preventive repairs of critical areas are crucial for long-term asset management. By significantly improving the quality of inspections Axpo can ensure they have all the information they need to manage and operate a first-class working energy infrastructure.
Eliminating inspection hazards
Safety first. With the P3, Axpo can now safely inspect assets at dangerous heights, high-voltage areas and hard-to-reach locations without putting employees at risk.
Thanks to Phase One P3 we can increase the efficiency of our pipeline inspections. We need fewer images, but we get more information and higher image quality e.g. position, orientation and objects are saved in the metadata and high resolution enable a detailed zoom function. The integrated feature rangefinder ensures moreover precise and fast focusing on every shot thus enabling a better standardization.
Contact a Phase One Expert
If you would like to learn more about our Payloads for Drones, our experts are eager to help! Contact us.
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