The transmission segment has introduced and incorporated several new technologies to accelerate the construction and development of transmission lines. As of March 2021, India had 441,821 ckm of transmission lines, up by nearly 4 per cent from March 2020, despite the imposition of lockdowns for controlling the spread of Covid-19.
Every year, transmission lines are being built across the country. With the growing integration of renewables into the grid, many of these lines are coming up in remote, less dense and geographically challenging terrain. Further, as the completion period of renewable energy projects is shorter (12-18 months) vis-à-vis that of transmission projects (24-36 months), developers need to use advanced technologies to speed up transmission line stringing and tower installation. Utilities are taking cognisance of these issues and deploying new technologies. A case in point is Sterlite Power Grid Ventures Limited, which was awarded the Northern Region System Strengthening project in mid-2014 and was completed two months ahead of schedule in October 2018. The transco deployed innovative engineering and construction methods such as helicrane construction, micro-pile foundations and special tower designs to commission the project rapidly.
Helicopter stringing
Several transmission companies are using helicopters for stringing lines over long distances, thereby reducing their dependence on manpower. Stringing wires also presents a workplace hazard for employees and helicopter stringing helps in minimising these risks. Moreover, helicopter stringing enables faster execution of conductor installation, which is otherwise a tedious and time-consuming process. Helicopter stringing is also more precise and does not lead to long periods of shutdown of transmission lines.
Maharashtra approved the utilisation of helicopter stringing for the construction of 765 kV single-circuit transmission lines for Bhopal-Dhule Transmission Company Limited. This had twofold benefits for the company. One, fewer land acquisition issues cropped up; and two, the commissioning of the project was faster and at a lower cost. According to studies, drone/helicopter-based stringing optimises the conductor stringing process by 30 per cent while minimising its adverse impact on the environment. Furthermore, many times transmission lines face outages and other maintenance issues requiring the operator to replace the transmission wires. At present, transcos use manual labour to replace the wires, which makes it a lengthy process. However, in the coming years, transcos are expected to deploy helicopter stringing and reduce the downtime and repair and maintenance costs.
Notably, private helicopter companies in Uttarakhand, Himachal Pradesh and Jammu & Kashmir that ferry people in hilly terrain have started to diversify their businesses to cater to the demands of transmission companies.
Helicopter cranes
Currently, the huge equipment used in transmission projects, such as transmission towers and substation components, is carried by trucks and other heavy transportation vehicles in many pieces and then assembled on site. However, in hilly terrain, the task of assembling heavy machinery is cumbersome because construction companies have to depend on mules and porters to carry equipment to the job site. This results in greater transportation cost, higher risk of breakage in transportation, and longer time overruns. The introduction of helicopter cranes has changed the dynamics and transformed the whole process. Heavy-lift helicopter cranes such as S-64 aircranes are capable of installing towers at high altitudes.
Sterlite Power deployed an aircrane to set up a power transmission line in the mountainous terrain of Jammu & Kashmir. The company partnered with US-based Erickson Incorporated to install transmission towers in the Pir Panjal ranges using Erickson’s S64 Aircrane, a heavy-lift helicopter. The company invested Rs 30 billion in order to construct transmission towers in this high-altitude section (9,000-12,000 feet).
Challenges and the way forward
Currently, several transmission projects are facing right-of-way (RoW) problems and land acquisition issues, which delay stringing and commissioning. These problems can be addressed by better planning and prediction technologies to forecast RoW problems as well as vegetation growth. Advanced prediction technologies will help in determining potential obstructions and troubles and reduce the possibility of unexpected RoW issues.
From a strategic long-term perspective, the transmission network is expected to grow organically at 4-5 per cent annually for several years, in line with the growth in previous years. Furthermore, this process will be favourably complemented by the growth of renewable energy installations. These installations will entail the construction of transmission lines. Therefore, the transmission network will become increasingly dense and transmit higher voltages.
Consequently, developers will come to increasingly rely on innovative technological methods such as LiDAR and unmanned aerial vehicles for surveillance, and helicopters for installing towers and laying transmission lines.