Last year’s November 1 power grid collapse that caused a countrywide blackout was initiated by simultaneous trips of the Bheramara HVDC sub-station and one or more generation units, which resulted in their total loss of around 734MW generation.
The findings were revealed by Buet professor S Shahnawaz Ahmed, who came up with the results after analysing the reports of two government committees and gathering necessary data from the National Load Despatch Centre and the HVDC substation.
Presenting his findings at the Bidyut Bhaban in the capital yesterday, he said 444MW power generation was lost because of a software problem at the HVDC sub-station and 290 MW more at one or more generation units. However, he could not identify whether one or more generation units was involved.
Phasor Measurement Units (PMU) or Digital Fault and Disturbance Recorders (DFDR), having time-synchronisation with the same GPS system, need to be installed at all large power plants and grid substations so that in the event of any fault triggering a blackout, the sequence of trips of generation units or lines can be identified, the findings claimed.
To prevent a repeat of such a blackout, the Bangladesh University of Engineering and Technology teacher recommended that synchronous (HVAC interconnection) or asynchronous (HVDC interconnection) channels are used to import power from neighbouring countries, or that a nuclear power plant with massive capacity is built in Bangladesh.
He also pointed out that while making a decision for the future, authorities concerned should consider the issue of spinning reserve, which is the extra generating capacity that is available by increasing the power output of generators that are already connected to the power system.
For this, a good option would be to import hydropower – which is cheaper, has a higher ramp rate and less start-up time for the plants – through separate express feeders (dedicated and direct interconnection) between Bangladesh and India, Nepal, Bhutan and Myanmar, Shahnawaz said.
He added that hydropower units – if partially loaded – can provide a fast spinning reserve whenever needed as well as ensuring a regular export volume.
However, besides spinning reserve and load shedding from the supply end, the emerging “smart grid” concept can partly be implemented in the local context of Bangladesh because of its weak communication infrastructure and its consumers’ poor affordability.
Power Division Secretary Monowar Islam and Power Cell Director General Mohammad Hossain were present at the presentation yesterday.