Outperforming helicopter inspections with drones and AI-enhanced inspection platform

ČEPS AS chose Hepta Group to perform aerial powerline inspection using unmanned aerial vehicles during the autumn of 2021. The scope of the project was to determine if it is possible to reach the same level of inspection accuracy using drones as with traditional manned helicopter inspection. Hepta was responsible for on-site data collection and analysis. During the autumn of 2021, Hepta collected RGB, infrared and LiDAR data of a 400kV/220kV common suspension towers, the total length of the project was 14.8 kilometres.

As ČEPS has a very high standard for data collection and inspection, Hepta took the approach of collecting large amounts of very detailed photos of the towers. Hepta’s operations team used the grid photo approach, meaning that the drone’s camera automatically took several zoomed-in photos of one tower angle. The average grid photo consisted of up to 80 smaller photos, giving excellent detail and overview of the state of the tower, meeting all ČEPS AS demands. An average of 820 photos was taken of one single transmission tower using two drones at the same time. The average time consumption for completely photographing one tower was around 30 minutes, depending on the complexity of the tower. Using the grid photo method, an average of 7 towers were photographed per day. In addition to the towers, Hepta also captured data of power lines with a total length of 118km. The total time consumption for the tower photo collection was ten working days. All in all, Hepta’s operations team rose to the challenge and were able to provide ČEPS with the necessary, high-resolution images.

Key figures:

• 820 photos of one single transmission tower
• 30 minutes spent on average on data gathering per tower
• 7 transmission towers and their lines covered by drones per day

• 2951 images captured per one kilometre of high voltage transmission line

As with the operations team, the analysis team was also handed a very complex project with very high requirements. This was mainly due to the number of images and a very detailed defect list (over 800 different defects and over 40 000 images needed to be analysed). Up to then, distribution and transmission line operators had relied on a handful of photos per tower, while ČEPS had over 800 photos of one single transmission tower. Working with such a large number of images and defects seemed to be a gigantic undertaking at first, but after taking the time to work out the techniques and routines, work started flowing. On average, Hepta’s analysis team was able to conduct a full tower inspection in around 3 hours, analysing over 800 photos in the process.

Key figures:

• Over 40 000 images analysed

• Average inspection time per transmission tower with 800+ images – 3 hours

• Very detailed defect list with over 850 defects
• A large increase of inspection speed and efficiency

ČEPS AS provided Hepta with quite a hefty challenge, due to the immense amount of images needed to be gathered and analysed. But thanks to effective drone inspections and analysis work conducted in our software, Hepta was able to meet the challenge and fulfil all of the goals. In the end, we were able to clearly show that gathering transmission power line data with drones and analysing it in our specialised inspection platform uBird, can outperform helicopter-based inspections and provide a cheaper, more effective alternative.