Wednesday 17 October 2012

Islanding Scheme for Delhi during Grid Disturbance

To safeguard Delhi and its surrounding areas from electricity supply disruption during grid failure, The Minister for Power Sh. Veerappa Moily and Chief Minister of Delhi Smt. Sheila Dixit announced the ‘Islanding Scheme for Delhi. At the joint press conference, Sh.Veerappa Moily said that Delhi is the first state to formulate such a scheme to overcome grid disturbance problem. The main objective of the initiative is to isolate our generating stations so that supply of power does not get affected even if the Northern grid collapses.

The proposed Islanding Scheme for Delhi has been developed with following objectives in mind: 

i. to isolate Delhi’s power system from the regional grid when grid disturbance is imminent 

ii. after isolation to continue to meet at least emergency loads or essential services like VVIP load, Delhi Metro Rail, Water treatment load, Indian Railways load and hospitals. The present quantum of essential load spread across various distribution companies of Delhi is about 930 MW. 

iii. To extend start up supply to generating stations in adjoining areas to facilitate early restoration. 

The Islanding Scheme envisages that fall of frequency to 47.9 Hz will be taken as indication that grid disturbance is imminent and islanding will be initiated. Ideally one island is preferred but due to peculiar network considerations of Delhi and limitation imposed by Rithala CCGT, there is no option but to create four islands, capable of meeting about 3400 MW of load during peak conditions, as listed below: 

(i) Dadri – Jajjhar-Pragati (part) Island (Peak load 2315 MW) 
(ii) Bawana CCGT Island (Peak load 600 MW) 
(iii) BTPS-Pragati (part) Island (Peak load 500 MW) 
(iv) Rithala CCGT Island (Peak load 20MW) 

Keeping in view the complexity of the Delhi Power network, creation and survival of the Islands, some additional features like development of intelligent system for centralized decision making, augmentation of generation within Delhi, maintaining dual source of supply to essential loads, training of system operators, etc. are proposed to be taken up under this scheme. 

The scheme which is expected to cost almost Rs. 25 Crore will be operational from January 2013. Initially, Delhi’s critical requirement of 930 MW will be Islanded. Further, the Islanding will then be extended to 3400 MW. 

The other states who have approached the Ministry of Power for similar arrangement are Punjab, Haryana, Utter Pradesh and Jammu & Kashmir. 

The Islanding Scheme is a consequence of two major grid disturbances during July 2012. At a subsequent meeting taken by Union Minister of Power with the Chief Ministers/Power Ministers of North Indian States on 6th August 2012, it was agreed that States would prepare their islanding schemes in consultation with CEA, NRPC and PGCIL within next three months and ensure their implementation within next six months. The Enquiry Committee constituted by Ministry of Power, to look into the detailed causes of these disturbances, has also recommended that efforts should be made for formation of electrical islands in case of imminent grid disturbance. The Study Group, constituted by CEA, for this purpose, deliberated on finer aspects of islanding and also interacted with experts from Tata Power, Mumbai and CESC, Kolkata, to share their experiences of islanding scheme in respective areas. Based on these deliberations, DTL submitted its report on Delhi islanding scheme to CEA. 

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