The natural resources for electricity generation in India are unevenly dispersed and concentrated in a few pockets. Transmission, an important element in the power delivery value chain, facilitates evacuation of power from generating stations and its delivery to the load centres. For efficient dispersal of power to deficit regions, strengthening the transmission system network, enhancing the Inter-State power transmission system and augmentation the National Grid and enhancement of the transmission system network are required. An extensive network of transmission lines has been developed over the years for evacuating power produced by different electricity generating stations and distributing the same to the consumers. The nominal Extra High Voltage lines in vogue are ± 800 kV HVDC & 765 kV, 400 kV, 230/220 kV, 110 kV and 66 kV AC lines.
The transmission lines are operated in accordance with Regulations/ standards of Central Electricity Authority (CEA) / Central Electricity Regulatory Commission (CERC) / State Electricity Regulatory Commissions (SERCs), keeping in view the voltage stability, angular stability, loop flows, load flow pattern and grid security.
Power Grid Corporation of India Limited (POWERGRID) is a CPSU looking after transmission sector. It was incorporated on October 23, 1989 with an authorized share capital of Rs. 5,000 Crore (Enhanced to Rs. 10,000 Crore in FY 2007-08) as a public limited company, wholly owned by the Government of India. POWERGRID started functioning on management basis with effect from August, 1991 and it took over transmission assets from NTPC, NHPC, NEEPCO and other Central/ Joint Sector Organizations during 1992-93 in a phased manner. According to its mandate, the Corporation, apart from providing transmission system for evacuation of central sector power, is also responsible for Establishment and Operation of Regional and National Power Grids to facilitate transfer of power within and across the regions with Reliability, Security and Economy on sound commercial principles.