In 2020, Innergex partnered with Aeriosense to perform a detailed inspection of 42 km of its transmission line that connects the East Toba hydroelectric plant in the Toba Valley to the BC Hydro power grid near Saltery Bay. With an annual energy output of 454,000 MWh, it is one of Innergex’s largest projects. Understandably, it is crucial for them to make sure that the transmission line is reliable and in good condition.
Challenges — Difficult Terrain and Vegetation
Much of the line is located in remote areas, on steep slopes with cliffs, creeks and rockfalls frequently intersecting the right of way. The vast majority of supporting structures are not directly accessible by vehicles, and a considerable portion is not easily accessible by foot. Some of the structures sit atop hills or on the side of steep rock faces.
Tall trees and steep slopes also meant that helicopters could not be very close to the lines and they would not be able to dip below the line due to the surrounding vegetation. And the mountainous terrain would necessitate a more powerful helicopter while increasing risk.
While all of the above pose challenges for conventional inspections; the use of UAVs and automated inspections helped alleviate many issues. It made it not only feasible but also economically sound to perform a detailed inspection of this long, hard-to-reach transmission line.
Some of the challenges facing UAV based inspection in this geography included limited take-off locations and line of sight to the structures which makes manual UAV inspection especially tricky.
Solution — Automated UAV Inspection
A UAV inspection was a perfect solution given the situation and challenges that the line presented. The UAV is nimble enough to dip below the conductors to perform close up inspection of the entire support structure. And since UAVs are unmanned, the safety risks would be substantially lower than with helicopters. This option also provides high quality actionable inspection data — close up images from every vantage point that help detect even the smallest of defects.
For this project the inspection automation software was particularly important as it allowed the flight crew to extend the range of inspections between the limited take-off points. It allowed the crew to quickly and confidently perform the inspection within this challenging terrain.
Experience in performing these types of inspections and working in similar types of environments definitely helps in planning how to overcome particular challenges and facilitates the delivery of a high quality, detailed inspection. Transmission line engineers are able to plan their maintenance activities using this inspection data.
Results — Great Return on Investment
In the end, the big reward for the inspection crews hard work was how truly satisfied the clients were with the deliverables and outcome of the project which included a comprehensive report with geolocated data, and a summary of prioritized issues that will improve the reliability of Innergex’s line for years to come.
The detailed and thorough inspection meant that engineers understood precisely the condition of the assets and could plan for future maintenance and capital expenditure. By identifying anomalies and issues early on and building a baseline for future comparison, trends can be established to allow for timely preventive maintenance. Future repairs and outages can be planned to reduce costs and avoid lost generation revenues.
The result is a great ROI for the inspection program.