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Overview

Under the Power for All mission, India has set a target of 200,000 MW of installed capacity by the end of 2012. The transmission segment has a major role in achieving this mission as an efficient transmission capacity and network will prove essential to transfer power from generating stations to distribution networks.

In the past, transmission planning was done with respect to generation and was focused on setting up transmission systems that could evacuate power safely; however, with the changing scenario, the transmission sector started to move towards integrated system planning because generation capacities are distributed unevenly in different regions. While thermal capacity is in the eastern region, hydro capacity is concentrated in the Northern and North-Eastern regions. The capacity is used to evacuate power according to the demand in other regions like the Western region; thus, the integrated system planning has turned out to be a good option.

In the central sector, the central transmission utility (CTU), known as the Power Grid Corporation of India Ltd (PGCIL), is responsible for national and regional transmission planning while the state sectors have separate State Transmission Utilities (STU). Private sector participation is negligible in transmission and there is only one public-private partnership project, the Tala Transmission Project. Four private companies have been granted licences for developing transmission projects. While three companies have entered joint ventures with PGCIL, one company is a private company that has been awarded independently.

Transmission network includes transmission lines and transmission substations through which electricity is evacuated from a generator to a distributor. India has over 126,999 circuit per km (ckt km) of 220 KV of transmission lines upto Jan 2010 and its substations are of 188,155 Mega Volt Ampere (MVA) capacity for 220 KV upto Jan 2010.

Growth in Transmission Network over the Plan Period

The development in the transmission system was carried out in coordination with the growth in generation capacity. New and advanced technologies were introduced in the transmission system for bulk power transmission. 220 KV of transmission power was introduced in 1960, and another 400 KV was introduced in 1977. HVDC and HVDC bi-pole transmission was set up back-to-back in 1989 and in 1990 respectively.

The transmission line expanded from 52,034 ckm during the sixth plan to 221,549 ckm during the eleventh plan (upto Jan 2010) while the transmission substation size increased from 46,621 MVA to 303,637 MVA from the Sixth 5-year Plan to as on the period under review (Jan 2010).

Inter-Regional Transmission

During the fifties, electricity was supplied by generating stations to load centres; however, with the increase in capacity, a state grid was built for ensuring reliability in power supply. Even though demand from different regions was rising, the resources were confined to some regions like the eastern and north eastern regions. One way to cater to the demand was to set up plants near the load centre but that was an expensive option. Another option, which was taken during the seventies, was to form regional grids. A regional grid interconnects regions and transfers energy, which further keeps pace with formation of public sector utilities like NHPC and NTPC.

The existing inter-regional power transfer capacity is around 18,700 MW, and is targeted to be raised to 37,150 MW by the end of the Eleventh Plan period. Power Grid Corporation has plans to enhance its capacity to 37,000 MW. Around 20,700 MW of new inter-regional links have been planned for the Eleventh 5-year Plan. India is now looking at linking the transmission system with its neighbouring countries Bhutan, Nepal and Sri Lanka. There are also plans to develop an undersea HVDC transmission link between Sri Lanka and India. Moreover, investments of Rs 550 bn have been planned at the interstate and intrastate levels to increase the inter-regional transmission capacity for the Eleventh 5-year Plan period.

The inter-regional transmission capacity was developed over the plan periods to promote the inter-regional power exchange business among players in different regions. The surplus and deficit regions are the main drivers of growth in inter-regional energy transfer. During FY08, 43,000 MUs of inter-regional energy transfer was facilitated, which was 13% higher than the previous year (about 38,000 MU).

The eastern and Northern region systems have a major share in the inter-regional transmission capacity. While the eastern region is abundant in coal, the Northern region is endowed with hydro resources; as a result these regions generate the most power and also meet maximum demand. Evidently, these regions have a major share in inter-regional transmission capacity also.

Formation of the National Grid

Due to India’s uneven distribution of resources regional grids were created in the early sixties for power planning and for operation of the electric power system. During the seventies, regional grids were in place and inter-connected operations were obtained. The development of regional grids was further accelerated by the central generating companies (NHPC, NTPC) that introduced regional power stations and constructed EHV (Extra High Voltage) transmission lines.

In the current 5-year plan, a transmission plan has been evolved for strengthening the regional grids to establish and to operate both the regional and the national power grid to facilitate transfer of power across different regions and to support the generation capacity addition programme of around 80 GW.

Power Grid is now working on the planned set up of a national power grid to facilitate transfer of power within the different regions in India by the end of the Eleventh 5-year Plan. This grid will support the inter-regional energy transfer and will exploit the country’s unevenly distributed energy resources. The national grid will also help the power-deficit regions to fulfill their demand from the regions that have excess power.

The Power Grid has achieved several milestones towards the development of National Grid such as the implementation of Asia’s longest Talcher-Kolar High Voltage Double Circuit (HVDC) bipole link including its upgradation and the commissioning of Muzaffarpur-Gorakhpur high capacity 400 KV D/C that interconnects all four regional grids (Northern, Western, Eastern and North-Eastern) and is operating as a synchronous grid.

The difficulty encountered during the construction of the transmission lines was the Right of Way (ROW), especially in the hilly terrains of the Northern and North-Eastern regions, which are endowed with hydro resources. Transmission Super Highways are the solution for the ROWs so that they do not cause bottlenecks in harnessing generating resources. Interconnection of these highways from different parts of the country will ultimately lead to formation of a high-capacity national power grid.

The objectives underlying the formation of National Grid are:

Many inter-regional schemes have been planned for the phased development of the National Grid. The brief status of inter-regional links under operation is provided in the table below.