The “flying guardians” of high voltage on a helicopter to monitor the electricity grid

The inspection, monitoring and protection of the over 70 thousand km of the Italian national transmission grid is the mission that Terna fulfils every day to guarantee a continuous and efficient service and maximum reliability of the high voltage electricity transmission infrastructure throughout the Italian territory. It is an essential activity, in which the company that manages the Italian national transmission grid invests around 50 million euros every year and that enables the identification and location of any anomalies in order to intervene promptly to prevent any faults or outages.

One of the main monitoring activities involves inspections carried out with a helicopter fleet which is of primary importance for asset maintenance.

Aerial inspections are checks that Terna professionals carry out using helicopters equipped with advanced technological instruments that enable the identification of anomalies on the power lines across great distances. Terna’s current fleet, which has been inaugurated over the past few weeks, is made up of 7 fully owned helicopters, 4 of which were purchased over the last year.

Gheppio, Assiolo, Cuculo, Ghiandaia, Cicogna, Nibbio and Falco are the names of the aircraft, representing specimens of Italian birdlife that also nest on the high voltage pylons owned by the company: six are single turbine by Airbus Helicopter, while one is twin turbine by Leonardo Helicopters.

«We have expanded our helicopter fleet to increasingly improve the effectiveness of the monitoring» explains engineer Antonio Piccolo, manager of Terna’s Development and Methods Office. Every aircraft is equipped with advanced technology - including four new Gimbal systems gyrostabilised with extremely high-resolution cameras - for the real-time view of data by scanning the power lines.

Thanks to technological innovation, the acquired know-how and the new extended fleet, Terna can now monitor around 175,000 km of power lines a year, i.e. two and a half times the extension of the Italian grid it manages.

«By using the helicopters, we manage to carry out three different types of inspections of overhead lines» explains Antonio Piccolo. «Every helicopter is currently capable of monitoring 240 km of assets a day compared with the approximate average of 15 covered on foot». This leads to considerable ‏efficiency and helps save time and money. Nonetheless, ground inspections remain an essential and complementary tool for the identification of any anomalies that cannot be detected from above.

The objective for 2024: doubling the team of operating specialists. «The activities with helicopters started as an experiment in 2014, then we acquired the first 3 helicopters in 2015 and monitored 35,000 km of overhead power lines. We gradually increased grid control activities year after year, reaching around 149,000 km in 2022. It is a process that is now entirely insourced» continues Piccolo.

The team of professionals is currently made up of 37 specialists with an average age of 38: one for each Terna Plant Unit totalling 33 and another 4 for Asset Management dedicated to LIDAR (Laser Imaging Detection and Ranging) surveys. The objective for 2024 is to double the number of specialists from one to two for each Plant Unit, thus reaching a total of 66 in addition to the colleagues in Asset Management.

All the types of monitoring. Aerial inspections are divided into three kinds: infra-red for the detection of any hot points, those employing LIDAR technology for tree interference and, finally, visual-instrumental inspections.

More specifically, the identification of hot points is particularly significant as it pinpoints localised overheating that represents a relevant and potentially-dangerous aspect, as hot points can represent a criticality for the integrity of our assets.

Infra-red inspections are aimed at detecting localised overheating on joints and connection terminals. These inspections cover 100% of overhead power lines: they employ a highly sensitive thermographic sensor that highlights even the slightest abnormal variation in temperature. They are carried out by helicopter, with a flight profile parallel to the line at a height near that of the power line - approximately 30-40 metres on average - with a speed of around 60 km/h and an inclination of 30 degrees with respect to the perpendicular between helicopter and asset.

Visual inspections are carried out every year on 50% of the power lines (i.e. around 35.000 km) with the objective of identifying anomalies such as damage, degraded components, rust on conductors and insulators, presence of foreign bodies. The remaining half is visually inspected from the ground. Thanks to an annual rotation of the sections to be monitored, Terna alternates helicopter inspections with those on foot. In this way, an entire monitoring cycle is carried out over two years both on foot and by helicopter. High resolution images and videos captured by 64 Mpx cameras, are used for visual inspections to provide a more accurate analysis of the tiniest details from above.

LIDAR inspections, however, are carried out every year on 100% of overhead power lines. In this case, the objective is the identification of potential tree interference, such as plants that could dangerously get near to live conductors.

«Once at a height of 120 metres above the conductors» explains the engineer Guido Spadini, manager of Terna’s Flight Operations «the helicopter moves at a speed of between 80 and 90 km/h to examine the vegetation surrounding the power line». These inspections help «assess the criticalities linked to the growth of the surrounding vegetation and intervene promptly for maintenance» stresses Guido Spadini. The characterisation of laser data and the georeferenced overlapping of the assets determine any possible interference, providing the operating structures of the Plant Units with the precise distances between the vegetation and conductors thanks to the processing of the information collected during the inspections.

In particular, LIDAR provides objective data on the distanced between the conductors and the vegetation avoiding a visual approach. This translates into an increased efficiency and effectiveness of detections, contributing to the identification and resolution of anomalies before they compromise the continuity of the service.

The decision support system. After aerial monitoring is complete, the data and information collected are integrated in a Decision Support System (DSS). This system indicates the time necessary to solve all anomalies in compliance with the established policies. The DSS plays a crucial role in interacting with the advanced Artificial Intelligence algorithms that lead the analyses and recommend the measures to be taken. It is the central storage of all the anomalies and faults registered up until that moment, together with risk models.

Professional training. To operate all the technological equipment, dozens of professionals from Terna Plant Units across Italy undergo a period of training at the company’s training centre located at the Marcigliana office in Rome. Terna in fact has an internal training Academy. The 33 professionals follow a dedicated and specific programme to acquire all the skills necessary to use the equipment. Training includes both theory lessons in the classroom and practical learning experience during which new specialists are supported by asset management colleagues or other experts.

Drones and Artificial Intelligence. Can drones replace the activities carried out by helicopters? «This is not easy to do at the moment, as we need to carry out large-scale monitoring throughout the national territory - explains Antonio Piccolo - since the current regulations make large-scale management rather complex. Drones must be flown by line of sight (VLOS Visual Line of Sight), so they need operators on the ground that move with them. It is therefore not a feasible solution at the moment to cover the entire electricity grid multiple times a year».

Starting from 2024, Terna will boast a fleet of 34 drones, one for each Plants Unit and one for Asset Management, to integrate electricity grid monitoring activities. The objective is in fact to use them to inspect pylons vertically. The aim is to cover a sample of over 4,000 pylons a year nationwide. The approach is considered an integration and represents a new phase in the asset monitoring process.

But innovation does not stop here and, for the future, Terna is also thinking of integrating Artificial Intelligence to support traditional monitoring activities. «We are currently developing the Automatic Failure Detection project to monitor overhead power lines using helicopters in synergy with colleagues from other companies. This system includes a pod with a LIDAR laser and three 150 megapixel high-resolution cameras pointing in different directions. The equipment collects high-quality data while flying above the lines as well as a LIDAR scan. The objective is to use this data to train an Artificial Intelligence algorithm capable of automatically detecting or assisting specialists in the identification of anomalies. The LIDAR pot featuring 3 cameras is a unique device on a European or maybe even global level, made to measure for our specific needs».