Inspection tools & technologies |
Drones transform plant inspections
The development of drones has made great strides. In Sweden, a complete hydropower station is being mapped to construct a perfect digital copy. Report By Lars-Magnus Kihlström
JOAKIM SMEDLUND LOOKS INTO the steeply rising, black throat of the power plant tunnel. The buzz of the drone’s electric motors grows fainter as it moves away on its mission, and soon the bluish light from the built- in laser scanner is not visible at all. The control unit Smedlund holds has no longer any function and the drone and its equipment, worth some 150,000 Euro, are engulfed in darkness.
“As time passes and all radio contact with the machine is gone, you can’t help but wonder if we’ve made a mistake and the drone lies crashed somewhere deep in the tunnel. It can take more than half an hour. But then it reappears and you can breathe a sigh of relief”, Joakim Smedlund says.
Black belt in drone flying A lot has happened in the almost 10 years since he
Above: Joakim Smedlund Below: Digital inspections team
started working with drones at Vattenfall, where he is part of the Research & Development department’s digital inspections team. “The first models required a black belt in manoeuvring to fly, but now the technology has developed enormously,” he says. The most advanced drones are not only able to avoid obstacles, they can also independently explore an area, in this case a longhydro power station tunnel, one kilometre into the mountain. The advanced laser scanner fitted on the drone is used both to document the surroundings and to navigate. This way, the drone can be sent on expeditions all by itself for as long as the battery lasts – more than 30 minutes – and then find its way back again.
A geometric twin Together with the rest of the team, Joakim Smedlund
is at the Juktan hydropower plant in northern Sweden. The mission is to measure, scan and build a geometric digital twin of all parts of the power station. The Juktan station is to be rebuilt and with the help of this digital geometry, the project will benefit greatly in the design phase, but also by allowing project participants to digitally visit the plant at any time. Having a digital geometric twin of the entire plant can also benefit throughout the life of the plant as changes over time can be followed up and included. The digital model is made up of a point cloud that can be navigated, much like Google Maps street views, but so precise that every distance can be measured with mm precision. “This is the acid test of digital inspection technology, and we have used all the technical systems, we have found in the last few years to fulfil the needs and wishes of our clients in the hydropower department. The key here is that we combine traditional surveying methods with new methods to achieve the accuracy needed,” says Anders Lindström, who leads the digital inspection team that includes himself, Joakim and around ten more people. Although the technology costs a lot, it is still much cheaper than the alternative of sending people into dangerous environments and having to build stairs and scaffolding to access and inspect, as in this case, a tunnel. The same applies to inspections of other facilities, such as inside the boiler of a district heating plant, or in inaccessible areas of nuclear power plants, as has been done the past few years.
Many areas of use Drones in all forms have become an increasingly
common sight in Vattenfall’s operations. They fly, swim or walk, and their efficiency makes them an important means of accelerating the transition to fossil-free energy production. In addition to inspections in hard-to-reach and
hazardous areas, they are also used to find leaks in district heating networks, to install scarecrows on power lines, and in wind power to inspect or even renovate turbine blades with a repair robot. Ten years ago, the focus was mostly on flying
drones, but today many different types are used, such as underwater drones, ROVs (remotely operated vehicle). In hydropower, they are used to inspect dam ice gratings, hatches, intakes etcetera, in offshore wind power to investigate seabed conditions and much more. At Forsmark nuclear power plant, an ROV examined a wet well, a basin placed at the bottom of the reactor vessel, to verify certain dimensions in connection with the redesign of part of the structure.
26 | December 2024 |
www.waterpowermagazine.com
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