The reason for Tuesday's power grid failure has not been announced officially yet, but energy experts said not developing and modernising the power transmission system along with the growth in generation capacity might have been causing such failures repeatedly.
Consumers in Dhaka, Chattogram, Sylhet and Mymensingh suffered from frequent power outages for several hours on Wednesday too after power was restored following Tuesday's blackout.
The investigation committee of the state-owned Power Grid Company of Bangladesh (PGCB) visited several power generation units Wednesday to find out the reasons behind the national power grid failure.
The committee members did not make any comment regarding the outage, but some officials of the Power Division and the PGCB said a grid line in Ashuganj became overloaded while others speculated that "cascade tripping" at a unit of the Ghorashal power hub caused the blackout.
Cascade tripping occurs due to frequency or other unbalanced conditions. When demand is more than the power generated, the frequency of generators goes down. When the frequency drops below a certain limit, the grid will trip. This will result in sudden loss of power. If demand is less than generation, it will also cause such situations, which are also called blackout or grid failure.
Earlier, on 6 September, the north and north-western parts of the country suffered from a similar power outage for around three hours.
Mohammad Hossain, director general of the Power Cell – the policy formation unit of the Power Division, told The Business Standard that there are some isolated areas where transmission systems need to be upgraded.
"Apart from that, the transmission system has enough capacity to supply electricity across the country."
He further said, "Until now, our targets were to increase the power production capacity and provide hundred percent electrification. But currently we are working on strengthening the transmission and distribution sector."
Md Jamal Ullah Jamal, former managing director of PGCB, said, "Grid failure may occur for different reasons – like trips at power stations, malfunction at the grid sub-station and technical glitches at any point of the distribution system.
"Modernisation of the system and regular upgradation will help to control such incidents."
Sources at the PGCB said the power generation has registered massive growth in the last 13 years, but the transmission sector has not received the required attention.
The country now aims to shift to a smart country by 2041 after making remarkable progress in digitisation, but the transmission sector has not been digitalised yet.
How PGCB operates transmission system
The PGCB supplies electricity at 50MHz frequency, which is essential for the grid stability.
The grid collapses if the frequency goes below 48MHz or above 52MHz and it fluctuates with the synchronisation between electricity production and demand.
National grid line's frequency goes up when consumption is lower than the production and goes down when the trend reverses, said officials.
A modern system shuts power generation units automatically when frequency goes up and brings units in production when grid frequency falls.
But the PGCB still depends on telephone calls to bring power plants in operation and shut them down to synchronise with the demand, said Dr Mohammad Tamim, professor at Bangladesh University of Engineering and Technology.
Is smart grid costly and cumbersome?
In the last 14 years, around $30 billion has been invested in the power sector that increased the country's power generation capacity from 4,942MW to 22,512MW since 2009.
But automation, smart grid and the Supervisory Control and Data Acquisition (SCADA) system have not been implemented despite repeated urge from internal and external experts.
Dr Mohammad Tamim said there are no barriers to make the system modern and digital other than lack of interest in the Power Division which is only focused on generation capacity build up.
NKSoft Corporation, which helps clients design and instantiate modern grid control, is currently working with two power distribution companies.
NKSoft Corporation Co-founder and Managing Director John Sakhawat Chowdhury said, "Setting up a smart grid is not a big deal. It could be done in a maximum of two years and it may cost around $200 million."
Mohammad Hossain, director general of Power Cell, said a plan to set up a smart grid is being prepared.
"We have already appointed a consultant to find out the best ways to make the transmission grid smart and modern," he said.