A year after grid collapse, power systems remain vulnerable
On July 30 last year, India woke up to its hour of shame, and darkness. An early morning grid collapse led to the worst global power failure, demolishing the myth of India’s superiority in operating power grid systems. A year later, while the government has corrected some of the issues responsible for the mishap, most of the work is yet to be done.
The grid failure last year had plunged 20 states into darkness; it was followed by a bigger grid collapse the following day. The collapse was caused by a combination of factors, including multiple outages that made the system weak, overdrawal by northern states, absence of power islands to insulate essential services and regions from the impact, backfiring of protection systems and the absence of regional inter-connecting links. In a hurried press conference on July 30, then power minister M Veerappa Moily had promised wide-ranging reforms, including tightening of the grid frequency band, ensuring states didn’t overdraw, auditing protection systems to improve grid health and setting up power islands.
An analysis of the key parameters of grid security through the past year shows the northern grid’s daily power frequency remained in the red zone (outside the permissible range of 49.5-50.2 Hertz) for most of the period. And, outages of transmission elements are as prevalent as they were a year ago. According to Northern Region Load Dispatch Centre (NRLDC) data, as many as 45 elements were under forced and planned outages on June 18 this year. On August 18, 2012, 45 elements were out; the number of lines under outage rose to 110 on January 18.
Also, northern states continue to overdraw, though the quantum of overdrawal has declined. Uttar Pradesh overdrew 90 Mw in April and 102 Mw in May, according to Central Electricity Regulatory Commission (CERC) data. Haryana overdrew 81 Mw and 69 Mw in April and May, respectively. Immediately before last year’s grid collapse, Uttar Pradesh was overdrawing 723 Mw, while Haryana drew 557 Mw more than the scheduled power.
Experts say complete grid security isn’t possible without functioning power islands. “Proposals of islanding schemes have been received from Uttar Pradesh, Punjab, Haryana and Jammu & Kashmir. Other states are being followed up,” the power ministry said in an e-mail response to a detailed questionnaire by Business Standard. The scheme works by cutting a region’s connection with the national grid in the event of a fault and subsequently, supporting its demand from generators within the island. No new power islands have come up since July last year.
“The problem is installing systems that are part of an islanding scheme requires investment by distribution companies. Given their ill health, it is a problem,” said a source close to the development. The power ministry said it had submitted a project report for a “country-wide secure grid scheme” at a cost of about Rs 5,500 crore for funding secure grid operations through the Power System Development Fund. The ministry claims it has sensitised states and audited protection systems.
The nerve centre of last year’s grid disturbance was a 400-Kv double-circuit transmission line between Agra and Gwalior, one of the half dozen AC links connecting the northern and western regions. A part of the line was under planned outage; the other half tripped, as demand from northern states shot up due to the failure of the southwest monsoon and surplus in the western region. Outage of this line led to cascade tripping the other links, disrupting the entire AC link and completely separating the northern region from the North-East-West grid.
A senior NRLDC official said the Agra-Gwalior line had been strengthened and upgraded to 765 Kv in May. “Further inter-connection link (765 Kv Satna-Gwalior and Gwalior-Jaipur) is under construction,” the ministry said. This is expected to further strengthen the transmission system connecting the two regions. The ministry also said it had filed a petition with CERC for tightening the frequency band to 49.9-50.1 Hertz. This would deter states from taking fault alarms casually. Also, the unscheduled interchange norms are being reviewed by the regulator.
However, a major problem, that of insulating state utilities from political interference, remains. During a hearing on the grid failure in CERC earlier this month, Avneesh Awasthi, who was the Managing Director of UP Power Transmission Corp when the collapse occurred, told a CERC panel he had to exempt certain areas in the state in July 2012 from emergency rostering (series of scheduled load-shedding to save the grid and manage high demand), owing to the election schedule. The state’s election commission had notified the election schedule of the Municipal Corporation, Nagar Palika and Nagar panchayat from May 25 to July 7.