Power line inspections fall into the category of “infrastructure monitoring”. These types of inspections are expensive, time-consuming, have a high repeat rate, and comply with the legislation that mandates them (inspections are generally required every 1 or 2 years, and in detail every 3 or 5 years). considerable line length. In Spain, for example, according to REE, there are 41,590 km of power lines, including high voltage (AT; 220 kV) and very high voltage (MAT; 400 kV). At the regional level, we can quantify, for example, Catalonia, with some 2,500-3,000 km of lines.
Do wixed wings UAS flights over power lines?
So far the most widely used inspection method is the one performed by manned helicopters and in specific areas with inspection by ATVs or on foot. But expensive helicopter operation is noisy and ecologically unsustainable. This is where we ask ourselves if the UAS sector, especially those with wixed wings, can be an alternative and provide new technological solutions that will complement or even replace the use of manned helicopters later. On the other hand, for about 5 years now, there is already an accumulated experience of multicopter UAS flights in the inspection of electrical towers.
Wixed wings UAS are lightweight, easy to transport and handle even in hard-to-reach areas. If they have a manual take-off and assisted landing system (BTOL- Bird Take-Off and Landing), they can land on a narrow ground clearance (5-10 m). But in order to ensure the operation in production today inspection of power lines, the key points are:
- Fixed Wing UAS weighing less than 2 kg.
- Minimum flight autonomy of 1h.
- Payload capacity to ship advanced miniaturized sensors.
- Have a 3G / 4G mobile telephone telecommunications system that allows flight telemetry control and data transmission in long range mode, beyond the limits of local communication links.
With these weight requirements (<2 kg), the Spanish aeronautical authority (AESA) allows companies that have registered as “BVLOS activities (flights beyond the line of sight)”, to carry them out, needing only the additional processing of a NOTAM.
As an added value, the operation with UAS also provides several additional aspects to highlight: a) electric motor (minimal environmental impact); b) low-level unmanned flight over power lines (more security); c) Flight without noise or inconvenience to third parties (less intrusion).
What is the achievable productivity with a lightweight Fixed-Wing UAS like our C2-L plus?
Based on the technical data that characterize our EXO C2-L plus Fixed Wing UAS (2kg weight, speed 60-70 km / h and autonomy of 1.15 h flight) we have carried out various flight operation designs on linear routes . In a standard option (simulated over a relatively remote area of communication routes) we considered: a) make 3 daily flights of 1.15 h duration per flight; b) each flight is carried out from the same take-off and landing point, moving these points along the territory close to the power line, allocating 30 minutes on each flight between the access ferry to the starting point and the return ferry from the end point to the landing zone; c) Estimated productivity per day of flight of 100 km of electric corridor. With these data, the following table has been prepared in which the kilometers of corridor inspected are indicated and the calculation of the number of days necessary to cover them, including as a variable the possibility of using 1, 2 or 3 UAS together.
|km power line||Number of days / 1 UAV||Number of days/ 2 UAV||Number of days/ 3 UAV|
Our current conclusion is that with a light Fixed Wing UAS (<2kg), such as the EXO C2-L plus, UAS flights in BVLOS mode are affordable up to 500 km, maximum 1,000 km on electrical corridors, from an operational point of view, of execution time and economic cost.
What kind of data needs to be taken during inspections?
The most frequent uses in inspections are those related to the management of assets of the infrastructure itself and to the monitoring of the service area around the power line; a) thermal inspections (photography or video) of the catenary (cable network or stay), bollards, insulators and separators with the support of algorithms for the automated extraction of information; b) RGB or multispectral inspections, to detect changes and the state of nearby vegetation (encroachment), especially in areas of difficult access, detecting by photogrammetry the distance between the lines and the vegetation; c) previous and evolutionary cartography in the construction of new lines; d) emergency monitoring; and e) Standard flights to calculate the heights of the infrastructure, stays and vegetation (these flights currently require larger Fixed-Wing UAS, with payload greater than 4 kg).
Waiting for a few more steps … in the regulations
Increasing the range of flight x2, x3 or more, having more capacity in the UAS to transport double or triple sensor, and a regulation favorable to BVLOS flights with UAS of more total weight (4 kg or> 4kg) would greatly expand the range of these flights on electric corridors opening up new possibilities for their systematic use. Exodronics is already working on new models that incorporate all these capabilities and other new features.
Currently in Spain, flights with UAS of more than 2 kg are prohibited and are only possible by companies authorized in “BVLOS standard operational scenario”. The processing of “operational scenarios” is laborious and can take between 6 and 8 months. Instead, it is possible to be optimistic since the next European regulation (July-2020) is expected to clarify and facilitate the regulations on UAS. In this sense, the FAA (USA) is moving forward. In 2019, it already authorized more than 20 companies to operate in BVLOS and, on the other hand, it is advanced in facilitating operations, such as the low altitude authorization and notification capacity (LAANC), an automated process for requesting and approving operations in space. almost instantaneous aerial.
UAS and electrical corridors: Main applications, specific advantages and challenges
The following table summarizes these aspects: