A committee headed by Central Electricity Authority (CEA) Chairman A S Bakshi, which probed the massive grid failures on July 30 and 31, has recommended the unscheduled interchange (UI) mechanism and protection systems to avoid grid disturbances be revisited. The UI mechanism, introduced in July 2002 in the western region, is a penalty structure for state utilities that default in drawing power, endangering grid security.
A Velayutham, member of the Bakshi committee, told Business Standard, “Under the UI mechanism, a frequency band of 49.5-50.2 Hz has been fixed. During low frequency, penalties imposed on states are high, while these are lower during higher frequency. During normal frequency, state utilities tend to deviate from the schedule, using the UI mechanism to their advantage. The time has come to phase out the UI mechanism, as both under-drawing and over-drawing by state utilities pose a threat to grid security.”
He added instead of the UI mechanism, the committee had suggested frequency control through generation reserves and ancillary services. “The UI mechanism is causing over loading of the lines, making the protective system pick up relay without a system fault and causing disturbances in the grid. In case of overloading of lines, voltage at the receiving end declines, causing the relay to rise and lead to undesired tripping. Therefore, frequency control needs to be adopted,” he said.
The committee also sought a review of the penal provisions of Electricity Act, 2003, to ensure compliance with directions issued by load dispatch centres and state electricity regulatory commissions. The committee also sought more autonomy to load dispatch centres in grid operation, along with improvement in planning and investment in the intra-state transmission system. There was a need to review transmission planning due to the growing complexity of the system, it said.