ECONOMYNEXT – Sri Lanka’s Ceylon Electricity Board could lose the ability to provide a stable 50 cycle frequency as two large hydro plants are running dry, which can lead to outages or damage to customer equipment, industry analysts warn.
The CEB has asked for sustained power cuts to conserve water for the dry season in February and March after a coal plant outage could not be filled with other thermal plants due to forex shortages.
A power grid supplying alternative current operates on a cycles where the current switches from negative to positive.
Sri Lanka’s power grid operates on a 50 cycles per second (Hz).
When demand rises from customers the CEB has to ramp up generation to avoid the frequency falling below 50Hz and reduce generation when demand falls to stop the frequency going above 50 Hz.
If it is not done, power supply will become unstable and customer equipment will be damaged. Sections of the grid can also fail.
This is why the CEB has to shed loads despite political or regulatory orders making power cuts ‘illegal’.
In most countries that changing demand and supply or frequency response is managed by a key power station.
In Sri Lanka frequency response is provided by Kotmale and Victoria power stations. Unlike thermal stations which run at maximum efficiency within narrow ranges, large hydros can vary their output widely.
The CEB uses either Kotmale or Victoria for the purpose.
However with the failure of a coal plant and the inability to get foreign exchange due to money printing, the CEB has been forced to run down Victoria and Kotmale to avoid power cuts.
CEB has sought to cut power for one hour cuts to conserve water. Earlier the PUCSL gave permission to cut power but the focus was on the short term consideration of available capacity.
“This is not a problem of day-to-day capacity availability,” an industry official said. “There are other implications which have knock on effects. That is why the load shedding was sought.”
Kotmale generation is expected to be halted to conserve water for irrigation after the Maha season ends.
Only Victoria is expected to be available for frequency control from mid March.
The CEB is rapidly running down its water storage which is already down to below 50 percent industry officials said.
Long power cuts of 3 to 4 hours may be forced on the only by late March unless loads are shed industry officials have warned.
Energy Minister Udaya Gammanpila has made similar warnings.
The rapid fall in storage is identical to 2019, which was a power cut year according to industry watchers.
The CEB runs its generators giving priority to drinking water, irrigation and then for its own use.
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Sri Lanka could face long power cuts, water shortages, grid failures from March
In Kelani River Castlereigh and Moussakelle, which are used to provide water to Colombo during the March – April dry season are expected to fall below operating level by February and March, depriving Colombo of water.
In another complication, Samanalawewa which is crucial to providing power to the Southern grid is also running down. The Southern grid which is in a 132kV section of the grid has limited generators.
Unless water is conserved large sections of the grid may face outages, industry watchers say. (Colombo/Feb14/2022)