Jan Vermeulen23 February 2023
Eskom spokesperson Sikonathi Mantshantsha has confirmed that the System Operator implemented stage 7 load-shedding during evening peak demand periods on Tuesday and Wednesday.
The System Operator, headed by general manager Isabel Fick, determines the level of load-shedding and issues the order for customers to reduce demand.
Those customers include municipalities and Eskom itself, which then cut power to homes and businesses according to their load-shedding schedules.
Since joining Eskom as head spin doctor in 2020, Mantshantsha has consistently posted Eskom’s evening peak statistics.
For the past two nights, Mantshantsha’s posts showed that the System Operator had implemented load-shedding of over 7,000 megawatts (MW).
By the Eskom System Operator’s own definitions, that is stage 8 load-shedding. Each stage represents an additional 1,000MW of demand removed from the grid.
Stage 1 load-shedding is up to 1,000MW, stage 2 up to 2,000MW, stage 6 up to 6,000MW and so forth.
Therefore, stage 8 is when between 7,000MW and 8,000MW of demand is shed from the grid.
On Tuesday, the System Operator was load-shedding 7,045MW at the evening peak, which occurred at 19:15.
Yesterday, it shed 7,092MW from the grid, with the peak occurring at 19:14.
“The System Operator’s job is to protect the stability and integrity of the power system,” Mantshantsha told MyBroadband.
“As you know, I publish the statistics after the evening peak to give the actual data at a particular point in the evening — the highest demand period,” he said.
He explained that the load-shedding stage Eskom announces upfront is an estimate of the amount of generating capacity in deficit for the time covered.
“However, the system is managed continuously, in real-time, to ensure there’s sufficient supply to meet demand all the time,” said Mantshantsha.
“This is being done by reducing the demand to match available supply at all times while maintaining a buffer reserve.”
Mantshantsha said that, at times, the demand could exceed the previously announced load-shedding estimate.
“As you will see in the figures, it is accurate to say at that particular time last night, load-shedding was stage 7,” he said.
“Eskom is currently load-shedding at stage 6, as previously announced.”
When looking at the System Operator’s public data, it shows there is a sharp rise in power demand going into the evening peak, which is currently around 19:00 every night.
However, demand rapidly drops off after that.
Therefore, the System Operator only needs to increase load-shedding during a brief window, sometime between 19:00 and 20:00.
Mantshantsha said he doesn’t know exactly how long stage 7 load-shedding was implemented, but it was for less than an hour.
“Demand usually picks up substantially starting from 18:00, so the 7,000MW [threshold] would have been [exceeded] just before the 19:15 peak,” he said.