Innovative Ways

Technology advances in transmission line stringing and construction

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.




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