A number of schemes have been planned for phased development of National Power Grid. Under first phase, keeping in view the wide variation in operational parameters of the regional grids, High Voltage Direct Current (HVDC) interconnections to interconnect Northern, Western, Southern and Eastern regions (Eastern and North Eastern regions are interconnected with AC lines) have already been achieved.
The interconnections between North and West (500 MW HVDC back-to-back at Vindhyachal), West and South (100 MW) HVDC back-to-back at Chandrapur) and East and South (500 MW HVDC back-to-back at Gazuwaka) and East and North (500 MW HVDC back-to-back at Sasaram) are under operation with cumulative inter-regional power transfer capacity of 5,000 MW under this Phase.
The transmission capacity addition under the second phase has already commenced with the commissioning of 1,400 km-long Talcher- Kolar bipolar 2,000 MW HVDC link, the largest in Asia and 1,000 MW Raipur-Rourkela 400 KV double double circuit AC link, enhancing the inter-regional links (State-owned), which are presently being utilised to exchange power between the regions in radical mode.
Currently, North-Eastern, Eastern and Western regional grids have been interconnected synchronously achieving a combined capacity addition of 50,000 MW stretching from Arunachal Pradesh in North-Eastern region to Goa in Western region a spread of 2,400 kms.
The National Power Grid is being strengthened through hybrid system consisting of high capacity HVDC and Extra High Voltage Alternating Current (EHVAC) lines. The inter-regional power exchange capacity has been planned to enhance to the level of 30,000 MW by 2012 through establishment of various interregional AC and HVDC links creating transmission highways.