Eskom cut 6,369 MW from the grid on Wednesday evening, which, according to the power utility’s load-shedding definition, equates to stage 7 load-shedding.
Eskom’s evening peak data revealed that it had 25,001 MW of generation capacity available while total demand was 31,660 MW.
Eskom used twelve open-cycle gas turbines – power stations that use diesel as their primary resource – to increase generation capacity.
It also added 1,416 MW of renewable energy to the grid, which included 973 MW of wind power, 103 MW of solar power, and 340 MW of concentrated solar power.
Eskom’s current load-shedding definition states that one stage of load-shedding equates to 1,000 MW of the national load to be shed.
That means stage 1 allows for up to 1,000 MW to be shed, stage 2 for up to 2,000 MW, stage 3 for up to 3,000 MW, and so forth.
That means that Eskom hit stage 7 load-shedding on Wednesday evening. However, it did not officially announce stage 7 load-shedding.
Energy expert Adil Nchabeleng previously said Eskom has decided not to inform the public when it exceeds stage 6 load-shedding.
“They are giving us the impression that everything is oscillating around stage 6, which is a lie. It is beyond stage 6 when considering the frequency of power cuts,” he said.
Energy analyst Chris Yelland said Eskom’s systems operator receives many complaints from people about load-shedding hours longer than what is specified for stage 6.
“I know for a fact there are certain municipalities are load-shedding certain areas differently to others – you may say in a discriminatory fashion,” Yelland said.
“So, it is happening where some areas experience higher load-shedding stages than what is public knowledge,” he said.
The table below shows the load-shedding data from Eskom over the last week. Eskom did not share its load-shedding information on 1 September.
|Date||Load-shedding (MW)||Announced Stage||Actual Stage|
|Sat, 2 September||3,664||Stage 4||Stage 4|
|Sun, 3 September||4,544||Stage 5||Stage 5|
|Mon, 4 September||5,067||Stage 5||Stage 6|
|Tue, 5 September||5,991||Stage 6||Stage 6|
|Wed, 6 September||6,369||Stage 6||Stage 7|
Eskom not following its own load-shedding definition
National Rationalised Specifications (NRS) Association of South Africa chairman Vally Padayachee revealed that Eskom never used its own guidelines and definitions of load-shedding stages.
Padayachee said that when load-shedding was first introduced, Eskom indicated it was 1,000 MW per stage.
He said one stage of load-shedding could vary from 800 MW to 1,200 MW cut from the grid, which is behind the confusion around load-shedding stages.
Although Eskom has never announced load-shedding above stage 6, it has, on some days, cut more than 7,000 MW from the grid. That equates to stage 8 load-shedding.
More recently, the megawatts cut from the grid have often exceeded the official load-shedding stage that Eskom announced.
The discrepancy, Padayachee explained, is because Eskom is not using the “1,000 MW per load-shedding stage” guideline it is promoting.
The new load-shedding rules – contained in the third edition of the NRS 048-9 Electricity Supply – Quality of Supply: Code of Practice – should resolve the confusion.
The consultation document details a revised load-shedding approach allowing up to Stage 16 power cuts.
Padayachee explained that they devised an innovative, simple, and less confusing way to govern load-shedding.
The new regime means that 5% of electricity demand is reduced for each stage of load-shedding. Stage 1 reduces 5% of demand, Stage 2 reduces 10%, Stage 3 cuts 15%, and so forth.
The electricity demand is forecasted for every hour of the day using a formula described below, with sample values in brackets.
- Demand (25,000 MW) = Forecasted hourly demand (30,000 MW) + Reserve margin (2,500 MW) – Curtailment load (7,500 MW)
They will then divide the demand with supply, which will show a surplus, where no load-shedding is needed, or a shortfall, which requires load-shedding.
If the shortfall is between 0% and 5%, Stage 1 load-shedding will be introduced. If it is between 5% and 10%, Stage 2 will be implemented.
The new document accommodates up to Stage 16 load-shedding, which means demand exceeds supply by up to 80%.