Tense 9 minutes for TNEB as state went dark at 9pm

Sivakumar.B@timesgroup.com

Chennai:07.04.2020

Senior officials of TNEB and state power minister P Thangamani spent tense moments at the discom headquarters as people of the state switched off lights to light lamps between 9pm and 9.09pm on Sunday, responding to a call given by Prime Minister Narendra Modi.

The power managers were taken aback when the power demand dropped by about 2,200 MW, as against their earlier assessment of 1,000-1,2000MW. However, the grid was saved from highvoltage problems like collapse of sub-stations, transformers, feeder lines and a possible blackout by shutting generation units to the tune of 2,200MW.

In 2012, the entire northern grid broke down, plunging several parts of north India into darkness for several hours. “In case of a blackout, generation facilities would take a hit and it may take about 10 hours to restart generation,” said a senior TNEB official. After breakdown, it may take days and weeks to get back to normalcy in distribution, he said.

As per Tangedco’s estimates, the peak lighting demand is only 2,000MW, and this includes streetlights. Officials feel that apart from lights, people could have switched off other electrical equipment too, throwing to the wind all advisories issued to the contrary in the last few days. The drop in demand in Chennai was about 350MW and the rest of it was in districts.

The total demand at 8.45 pm on Sunday stood at 10,091MW. At 9pm, it was down to 9,012MW and at 9.10pm the demand stood at 7,908MW, said the official.

“At 9pm we put our thermal, hydro and gas units on standby mode to prevent surge in voltage in the grid. After 10 minutes, when the demand started increasing, we restarted gas and hydro units. Thermal units were restarted at slow pace. The power frequency in the grid touched a maximum of 50.25hz and we successfully managed to keep the voltage at normal level,” said the official.

Across the country, demand fell by 31,000MW on Sunday night. “The drop in southern region was 6000MW,” said the official.

Some areas in Chennai complained about voltage fluctuations on Sunday night and Monday morning. “Some transformers may have given trouble. But we have restored normalcy,” said the official.