Wind turbine inspection by drones

Unmanned aerial vehicles (UAVs), commonly known as drones, are aircraft without human pilots on board. They may be operated either through remote control or autonomously by onboard computerised systems. Given the steady increase in its usage in different industrial applications, drone technology is being rapidly commercialised. One of its emerging applications is wind turbine and blade inspection. Traditionally, these inspections are done by people who climb to a height of about 100 metres to reach the hub of the wind energy generator. In manual inspections, the rope access method is used. The inspectors take pictures of turbine rotors and blades with a small digital camera to be analysed later for faults. However, this method is slow (one or two turbines are covered per day) and unsafe. With the use of drone technology, the inspection process can be made faster and safer.

The drone technology solution developed by Martek Marine uses optimised hardware and data collection processes. According to Jamie Allan, UAV strategist, Martek Marine Solutions, the technology can conduct a minimum of 10 turbine inspections per day and operate even in extreme weather conditions. The solution comprises a cloud-based asset management portal, which allows operators or inspectors to view the images and defect analysis conducted by the blade tech team on an intuitive map-based system from any location and use the data as required. Consistency and repeatability of these inspection systems enable the collection of accurate historical inspection data and monitoring of blade degradation. This, in turn, enhances their predictive maintenance capabilities, which can lead to reduced downtime and greater revenues.

Although drone technology is being increasingly used for the inspection of wind turbines and blades across the world, it has not yet entered the Indian market. Since UAVs will have to fly to heights of 80-100 metres to inspect blades and rotors, they would have to comply with the rules and regulations of the Directorate General of Civil Aviation (DGCA). The DGCA had banned UAVs in 2014, and then released draft regulations for UAV operations in April 2016. The final regulations have not yet been released and thus, UAVs continue to be banned in India.

The draft regulations impose several restrictions on the operation of UAVs for wind turbine inspections. For instance, the height restriction of operating drones only with a 500 metre visual line of sight during the entire period of the flight makes these drones unviable for large onshore and offshore wind farms. Further, operating drones under VFR (visual flight rules) restricts their application, particularly in areas where inspections may be needed at night time or during rain and storms. The use of IFR (instrument flight rules) modified for UAVs is not permitted under the DGCA draft regulations.

UAVs are currently being adopted for wind turbine inspections in countries where the civil aviation authority allows the use of drones for commercial operations. For this purpose, the UAV operator has to provide documentation, which includes the operations manual, and risk assessment and method statement. Further, the absence of common international or regional standards is a key challenge in the creation of a global market for UAV solutions providers. Nevertheless, the future looks promising. According to Allan, the finalisation of standards at the global and local levels is expected to happen soon, owing to the increasing use of drone technology across multiple industries. As most of the global wind energy original equipment manufacturers and operators are using or strategising drone technology for their business needs, the use of UAVs for inspection purposes is set to grow in the near future.

In India, the final regulations on UAVs, as and when they are released by the DGCA, would pave the way for commercialisation of drone-based solutions for wind energy turbine rotor and blade inspection. Given the growth of wind energy installations in India and the commitment to install 60 GW of wind energy capacity by 2022, drone-based turbine inspection solutions are expected to witness significant uptake provided the final DGCA regulations are favourable.



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