It was too big for control system
A system that prevents widespread electricity blackout in case a major power source trips failed to function as it was supposed to on Saturday.The tripping of Bheramara interconnector station, through which 450 megawatts of power was being imported, was too much for the “under frequency relay” system to prevent the blackout, experts told The Daily Star.According to sources in the Power Grid Company of Bangladesh (PGCB) and Power Development Board (PDB), when there is a sudden failure of a power generation source, the under frequency relay is supposed to shut off equal amount of electricity supply to localities.This prevents other power plants from shutting down in a domino effect due to the abrupt supply shortfall.
In Saturday's case, when there was a circuit failure in the Bheramara interconnector station, it created a shortfall that affected some private power plants before the relay system could kick in. The power grid was restored yesterday.“This caused a chain reaction among the power plants connected to the national grid,” said a PDB official. There are more than a hundred small, medium and large power plants connected to the grid.
The official added that Bheramara station was handling around 440MW of power import at the time of the disaster, when the country's power demand was 4400MW.“This shortfall was just 10 percent of the demand. Although the under frequency relay is supposed to handle up to 10 percent sudden shortfall, it could not handle this shortfall in the way it was expected to and consequently the country's power plants faced shutdowns,” the official noted.In recent months, the Meghnaghat 450MW power plant tripped once, but it did not trigger nationwide blackout because the system had worked then. The plant was contributing less than 10 percent of the supply at that time.According to a PGCB high official, the developed nations prevent blackouts by managing the power supply side by keeping excess power online.“But we are chasing demands …. We manage the situation by managing the demand side. Honestly, managing the demand side is not an efficient way to prevent a blackout when a major power source goes out,” the official said.The official added that the country's transmission and distribution system has been handling similar situations under this management for decades.But as power generation has doubled in the last seven years, the transmission and distribution system needs to be upgraded.
“We also intend to manage the transmission system from the supply side from 2021-22, when we expect to have a lot of surplus power,” the official said.The government forecasts that power demand in 2020 would go up to 17,600MW. It will jump to 24,956MW in 2025 and 33,000MW in 2030. This year's peak supply and demand stood at 7,403MW in mid-July.According to a power system expert, the country should have an independent system operator that would focus on operating power generation, transmission and distribution without any interference from any authority.As we are building several large power plants, like the 1,000MW nuclear power plant in Rooppur, the 1,320MW coal plant in Rampal, and the 1,200MW coal plant in Matarbari, upgrading the distribution and transmission line becomes even more important.Besides, the government is also working on importing another 500MW power from India through the Bheramara station.Because if any of these plants trip, when they are operational, it would create a greater power shortfall and the consequences would be similar or worse than what had happened on Saturday.
Meanwhile, the power secretary met Finance Minister AMA Muhith to discuss how to improve the country's transmission and distribution system in the near future.After the meeting, Muhith told the press that Saturday's blackout had stemmed from Bangladesh's power transmission system, not due to any problem in India. The transmission system needs improvement, he added.
