The transmission of electricity is defined as bulk transfer of power over a long
distance at high voltage. In India, bulk transmission infrastructure has increased
from 3708 ckm in 1950 to more than 300,000 ckm. up till now. The country has been divided
in to five regions for transmission of electricity. The planning of transmission system in
the country, had traditionally been linked to generation projects as part of an evacuation
system. Ability of the power system to safely withstand a contingency without generation
rescheduling or load-shedding was the main criteria for planning the transmission system.
However, due to various reasons such as spatial development of load in the network,
non-commissioning of load center generating units originally planned and deficit in reactive
compensation, certain pockets in the power system could not safely operate even under normal
conditions. This had necessitated backing down of generation and operating at a lower load
generation balance in the past. Transmission planning has therefore moved away from the earlier
generation evacuation system planning to integrated system planning. While the predominant
technology for electricity transmission and distribution has been Alternating Current (AC)
technology, High Voltage Direct Current (HVDC) technology has also been used for interconnection
of all regional grids across the country and for bulk transmission of power over long distances.
Status of transmission sector up to Jan 2005 is given in Table 5.
Table 5 - STATUS OF TRANSMISSION SECTOR UP TO JANUARY 2005
| Transmission Lines (Ckm.) | |||
| Central Sector | State Sector | Total | |
| 800 kV | 902 | 409 | 1311 |
| 400 kV | 38325 | 22181 | 60416 |
| 220 kV | 9191 | 97080 | 1,06,271 |
| +/- 500 kV HVDC Lines (Ckm) | 4372 | 1504 | 5876 |
| Converter Terminal(MW) | 7000 | 2000 | 9000 |
| Substations (MVA) | |||
| 400 kV | 30,375 | 42,800 | 73,175 |
| 220 kV | 3,566 | 1,34,746 | 1,38,312 |
| HVDC Back to Back | 2500 | 0 | 2500 |
Source:www.cea.nic.in
Perspective Programme
The country’s transmission perspective programme for 10th and 11th plan focuses on the creation of a National Grid in a phased manner by adding over 60,000 ckm of Transmission Network by 2012. Such an integrated grid shall evacuate additional 1, 00,000 MW by the year 2012 and carry 60% of the power generated in the country. The existing inter-regional power transfer capacity is 9,000 MW, which is to be further enhanced to 30,000 MW by 2012 through creation of “Transmission Super Highways”.
The Phase wise details of the programme are as under:
INVESTMENT PLAN
Phase-I: Considering wide variation of electrical parameters in various regional grids, mostly HVDC interconnections were established between the regions. This phase was completed in the year 2002, thereby achieving inter-regional transfer capacity of 5,000 MW
Phase-II: During this phase, inter-regional connectivity is planned to be strengthened with hybrid system consisting of high capacity AC (765 kV & 400 kV) and HVDC lines. Such a National Grid is envisaged to disperse power not only from Mega generation projects but also to enable transfer of bulk power from one part of the country to another in different operational scenarios. The inter-regional transfer capacity has been enhanced to 8,000 MW. This phase is likely to be completed by the end of the year 2007, and the cumulative inter regional capacity would be enhanced to about 23,000 MW, depending upon commissioning of planned generation projects.
Phase-III: Further strengthening of National Grid is envisaged through 765 kV AC lines HVDC lines to Southern region and linking North Eastern Region with rest of the National Grid through high capacity transmission system. This phase is planned to be implemented by 2012 i.e. at the end of XI plan and would enhance cumulative inter-regional power transfer capacity to about 30,000 MW.
Funding
Out of the Rs. 8,00,000 crores required for doubling the power capacity to 2,00,000 MW by the year 2012, about Rs. 2,00,000 crores would be required for the associated transmission system including creation of a National Grid. Out of this, an investment of about Rs. 71,000 crores would be required in Central Sector Transmission Systems alone. POWERGRID is expected to mobilize an investment of Rs.50,000 crores from its own resources. The balance requirement of Rs. 21,000 Crores is proposed to be mobilized through private investments. Considering the scale of investment and the volume of expansion required, attracting large private investment in transmission is essential. The Government of India amended Indian Electricity Act and Electricity Supply Act in 1998, to enable private sector participation in transmission sector. In January 2000, the Ministry of Power issued detailed guidelines for private sector participation in transmission. The Guidelines envisage two routes for inviting private sector participation. One route is through Joint Venture of POWERGRID and private investor. The other route called IPTC (Independent Power Transmission Corporation) shall facilitate private investor including investors coming through FDI to invest 100% by themselves.