The electricity sector is set to witness accelerated technological transformation of a multidimensional character, which will facilitate rapid capital expansion, aid in operational optimisation and enhance the resilience of the grid as a whole. The transmission segment is at the forefront of incorporating technology, as evidenced by its usage of light detection and ranging (LiDAR) technologies and drones to fast-track surveillance and monitoring, and expedite the execution of transmission projects.
Need for aerial monitoring and surveillance
Transmission projects and their construction consist of three fundamental processes: laying tower foundations, erecting transmission towers and stringing the transmission towers with conductors. This seemingly straightforward process becomes complex after factoring in and considering that transmission lines pass through private properties, dense urban habitation, protected forests, railway crossings, waterbodies, and hilly and uneven terrain over diverse soil types.
Therefore, transmission project managers tend to engage in a comprehensive process of planning, holistically considering all of the above factors as well as the budgetary resources at their disposal, before determining a suitable route and design for the proposed transmission lines.
The conventional methods of planning utilised for the installation of transmission lines include walkover surveys and other similar methodologies that have an oversized dependence on human intervention. However, these methods are inaccurate, owing to errors in human assessment and an array of technical challenges that arise in the course of monitoring. Moreover, these erroneous feasibility studies, and assessments based upon them, eventually result in time and cost overruns when technical complexities, environmental obstruction and right-of-way (RoW) issues arise. Hence, transmission projects get delayed even at the first stage of planning, monitoring and land acquisition, and the problem is further exacerbated by delays at later stages. Therefore, transmission companies stand to accrue major benefits, far exceeding their investment by harnessing LiDAR and aerial monitoring techniques for surveillance, given the potential for massive improvement in planning precision and execution speed.
Utilities are adopting advanced technological tools for monitoring transmission systems, to collect data via mobile and automated aerial devices. For instance, LiDAR technology eliminates the need for physical visits to tower sites. The LiDAR data collection method offers a fast turnaround time from collection to delivery, and the ability to accurately map terrain and deliver high resolution images of towers.
Essentially, the data derived through LiDAR surveys is fed into a modelling software, which utilises data analytics as well as machine learning to extrapolate the future growth of construction and prevent any potential RoW issues through prior estimation of vegetation growth by detecting patterns from the data supplied for previous years. A key advantage of a LiDAR survey over conventional surveys is the speed of data capture. In addition, the data collected by a LiDAR survey can be connected directly to PLS-CADD. Models can be created in PLS-CADD using the data to assess the different criteria for selecting the location of transmission lines and towers. Furthermore, LiDAR captures artificial and natural objects under and around transmission lines. This information is extremely useful for understanding tower locations and structural quality, determining model transmission lines, undertaking vegetative critical distance analysis, and performing repair and planning work in a corridor of transmission lines. Thermovision cameras and LiDAR can help detect loose connections, load imbalances and corrosion, all of which lead to temperature changes that can result in device malfunction, power outages and system losses.
India’s largest transmission utility, Power Grid Corporation of India Limited (Powergrid) has deployed helicopters equipped with gimbal-mounted LiDAR, thermovision cameras, corona cameras, and high resolution video and digital cameras to identify defects in its transmission lines. Through aerial patrolling, Powergrid can cover 100-150 route km in a single day. Faults such as infringement of safety clearances by trees/ bushes, adjacent side objects and broken insulators can be easily identified through aerial patrolling. Critical faults such as hotspots can be identified using thermovision techniques.
Private sector major Sterlite Power deployed LiDAR technology for the construction of the Bhopal-Dhule transmission project, executed by its subsidiary Bhopal Dhule Transmission Company Limited to conduct topographical mapping. According to the company, LiDAR beams transmitted from the aircraft helped Sterlite Power in overcast and cloudy conditions, providing high precision at a high speed. With the use of these technologies, the risk of project execution was significantly reduced. Sterlite Power is also utilising LiDAR technology to conduct topographical mapping in the under-construction Udupi-Kasargode transmission project.
Aerial drones and UAVs
Currently in the transmission sector, aerial drones and unmanned aerial vehicles (UAVs) are utilised for aerial surveys and monitoring and charting of land masses in addition to more complicated operations such as delivery of materials and automated stringing. Meanwhile, UAVs are fitted with gimbal-mounted ultra HD video cameras, capable of closely capturing high quality images and videos. For companies, drones are a cost-effective, efficient and safe solution for the inspection of power lines. They also improve safety, increase reliability and reduce transmission system response time. Drones are also used by transmission utilities to assess potential site locations, design site layouts, generate 3D visualisations, and make estimates for RoW. High voltage power lines in remote areas present difficult and dangerous obstacles, either when conducting routine inspections or surveying the damage after a storm. Such challenges could be removed with drones. Drones also give utilities the ability to identify threats to the energy grid quickly and efficiently.
Powergrid uses drones to patrol and survey its transmission line infrastructure. Drone patrolling provides the transco with detailed information about the tower top, such as the condition of the insulator, earth peak and earth wire.
In July 2020, Maharashtra provided complete authorisation to utilise drones for the inspection of power lines and transmission towers. Drones were already being used for aerial surveillance and inspection of extra high voltage lines and towers in remote areas of the state, but with this notification they will be more widely used. These drones are equipped with ultra HD cameras that can take high resolution close-up photographs and videos of the towers and their components. It is expected to reduce maintenance costs and losses from outages, as surveillance through drones is more efficient than manual survey of power lines, with quicker fault detection.
Sterlite Power extensively deployed aerial technology in the NRSS-29 transmission project in 2018 to overcome some of the toughest challenges of the Kashmir valley. Helicranes, used for the first time in Asia, were deployed to deliver over 3,500 tonnes of material to the site safely. In addition, drones and helicopters were used in wire stringing and providing aerial surveillance.
Issues and challenges
The challenges that beset drones and LiDAR applications are fundamentally of a regulatory nature, since the Ministry of Civil Aviation has introduced the Unmanned Aircraft Systems Rules, effective March 15, 2021 onwards, regulating the usage of drones and UAVs. The rules mandate that individuals and institutions that desire to use, manufacture, trade or import drones and UAVs to obtain approval from the Directorate General of Civil Aviation. It obliges UAVs to not fly above 60-120 metres from ground. It also necessitates users to acquire a licence before they can use UAVs. Any contravention in complying with the above rules and regulations could result in penalties ranging from Rs 10,000 to Rs 400,000.
These measures could discourage the use of drones and UAVs, which would have adverse effects on the planning and execution of transmission projects. Indeed, it is possible that several transmission companies would be reluctant to utilise drones, which would subsequently delay their commissioning. Therefore, the onus is on the government to modify the regulations and facilitate their usage for purposes of infrastructure development.
The way forward
In the coming years, it is inevitable that UAVs and LiDAR-based technologies will become more ubiquitous, as regulations are expected to be streamlined. Undoubtedly, they offer unparalleled accuracy, speed and reliability in monitoring, planning and maintenance of transmission lines. Using them helps in trimming the costs uncured by transmission companies with respect to grid surveillance and maintenance, as well as reduce the time taken to determine a route.