The Northern Grid, which collapsed twice in the summer of 2012 due to power overdrawal (more than the scheduled load), was hit by underdrawal by northern states on the intervening night of Monday and Tuesday.
About 31 main transmission lines tripped due to the grid’s high voltage, triggered by sharp reduction in the power demand in view of widespread rain and high-velocity winds.
The grid frequency reached 50.67 Hz at 3 am on Tuesday as the demand dipped from 29,000 MW to 18,000 MW. Usually, the frequency is in the range of 49.7 to 50.5 HZ. Emergency lines were opened to control the high voltage.
Punjab, Haryana, Delhi, Himachal Pradesh, Jammu and Kashmir, Rajasthan, Uttar Pradesh and Uttarakhand draw power from the grid. Of these states, only Uttarakhand did not underdraw power on Monday night.
Last year, the grid had collapsed due to low frequency on July 30, 2012. Another failure four days later had led to a cascading effect and the collapse of three more grids, plunging as many as 21 states into darkness.
“Due to bad weather in the northern region, the electricity demand dropped by about 10,000 MW at 11 pm on Monday. It led to high-frequency and high-voltage conditions in the grid,” read the communiqué of RK Sharma, an official of the Northern Regional Load Despatch Centre (NRLDC), which controls the grid operations. The communique was flashed to all states to adhere to the grid rules.
Ironically, states such as UP, Rajasthan, Punjab and Haryana, which were largely responsible for overdrawal last summer, were again to be blamed for the high voltage on Monday night. Rajasthan underdrew 3,850 MW, UP 2,300 MW, Haryana 1,750 MW and Punjab 1,450 MW.
Nearly 22 power stations of the grid, having a capacity of 5,686 MW, were already off when the high voltage was recorded.
“It was a sudden reduction (in power demand). We had also closed our three power productions units, but still the demand was much less due to eth rain, which has ended agricultural consumption. No major transmission line was damaged in Punjab, but 25 grid stations were out of operation due to heavy rain and high-velocity winds,” said Arun Kumar Verma, director, distribution, Punjab State Power Corporation Limited (PSPCL).
Meanwhile, the NRLDC has advised the states to take prompt action in case of another load crash, as it is fearing a demand reduction of 7,000 MW on the intervening night of Tuesday and Wednesday.