Energetica India Magazine: september 2020

48 energetica INDIA- September_2020 Abstract: India’s power grid has been in a state of rapid evolution due to increased load demand. The past decade has seen sub- stantial changes in the Indian power eco- system. Going forward, the future, which is dominated by urban evolution, evolving demographics, and expanding renew- able will need to adopt innovative means of solving energy delivery challenges. High rate of growth requires increas- ing transmission infrastructure at a rap- id pace, which in turn needs more and more space on the ground for right of way (ROW) for transmission lines and substations. Moreover, the faster pace of addition in Grid of Renewable Gener- ation (RE) has put additional pressure on reducing timelines for enhancing trans- mission infrastructure. The solution, lies in maximizing power carrying capacities of existing transmis- sion corridors. This will help to not only meet the growing demand faster and more economically but also have a posi- tive impact on the environment overall, as existing infrastructure use is maximized before deploying additional resources. Hence, transmission system owners, op- erators and planners need to consider sufficiently wide range of solutions that can exploit additional capacity of the existing system without compromising safety margins. The possible means to achieve this is with help of Uprate and Upgrade of the existing infrastructure of Transmission. Full paper: Solutions for Uprate, help to increase and/or unlock the latent potential capac- ity of existing Transmission lines, in the same Right of Way (RoW) by means of reconductoring, use of Dynamic Line rat- ing (DLR), use of Power Flow Controller and by simultaneously enhancing the life POWER SECTOR Technical Paper: Enhancement of Existing Transmission Line / Corridor Capacity - The Necessity & Methods Biswajit Mukherjee, Smruti Mohapatra, DK Ashok, Amitabh Singhal, Manish Agarwal Sterlite Power Transmission Limited of existing infrastructure with tower coat- ing solution. Solutions for Upgrade help to transform the complete transmission backbone of the system with help of voltage upgra- dation of existing transmission lines with Insulated Cross Arms and or other solu- tions, with reduced additional Right of Way (RoW) in existing corridors. These technologies, which are enablers of power unlock, can help Indian Utility & planners to build a robust & resilient Grid. The details of these technologies are explained here with their specific ad - vantages and differentiation. Dynamic Line Rating: Transmission lines should ensure safe, reliable and assured power delivery. In India, renewable energy sources are being added rapidly while transmission lines traditionally had longer lead times to be built to evacuate the power. It may also happen that load on a transmission line has increased while alternate infra- structure to share higher load is still un- der development. In such situations, it would be great to have a solution which temporarily allows higher power to be safely carried on existing transmission lines. Dynamic line rating (DLR) is an over- head transmission line real time moni- toring system. DLR sensors are becom- ing popular globally with the utilities for enhancing effective line capacity. DLR once installed on the line conductor, provides real-time situational awareness of conductor temperature, sag, current, and weather conditions. Additionally, it provides predictive load model to effec- tively enhance the line ampacity, under favourable weather conditions. Depending upon the weather, transmis- sion line capacity can be enhanced, and reliability can be increased by using DLR devices across the lines. The ampacity of conductor is usually calculated at follow- ing ambient conditions. • Ambient temperature: 45 o C • Solar radiations : 1045 W/m2 • Wind Speed : 0.56 m/s In reality, weather conditions are never simultaneously equal to above values, which provides opportunity to take ben- efit of favourable weather condition to allow higher current on the line, without violating the operating temperature and sag limits. The DLR is a simple device which along with a weather station (see figure-1) is easy & quick to install, voltage agnostic and is relocatable. Figure-3 shows the changing weather conditions for a dayat one of the pilot installations of DLR in India. Figure-2 shows the actual line current (blue curve) against the allowable line current (orange curve). The static design limit of line am- pacity was about 200 A. It is clear from these curves that for all periods of ob- servation, the allowable line loading was much higher than the static limit. Experi- ence from various installations indicates that on average 15-20% additional power can be unlocked. Understanding the transmission line with Figure 1 DLR & Weather Station in- stalled on a Transmission Line