Eskom proposes Stage 16 load-shedding schedules

Eskom has confirmed that a new national standards document proposes providing load-shedding schedules up to Stage 16.

The power utility told MyBroadband this is to ensure that should load-shedding beyond Stage 8 become necessary, it is done in an orderly fashion.

“The NRS048-9 Revision 2 describes load-shedding stages up to Stage 8 and obligates all network operators (distributors and municipalities) to develop, publish and implement these schedules when instructed to do so by the System Operator,” it said.

The Eskom System Operator is responsible for ensuring the stability of South Africa’s power grid and sets the level of load-shedding needed to do so.

“Beyond Stage 8, the System Operator will instruct each province to reduce by a fixed [megawatt] amount. This will be split between the Eskom Distribution network owner and the municipal network owners in each province,” stated Eskom.

“While this is effective in maintaining system stability, there are no predefined schedules of how this additional reduction should be rotated,” Eskom added.

“It is for this reason that NRS048-9 Revision 3 proposes load-shedding schedules up to Stage 16 in order to make load-shedding systematic and orderly,” the power utility said.

Until now, there was no official indication of how high the revised load-shedding schedules would go.

Eskom said the revised document also proposes more stages of load curtailment, although there are some practical limitations on industrial plants.

Earlier in May, National Rationalized Specifications (NRS) Association chair Vally Padayachee revealed that they had updated the Code of Practice for load-shedding with stakeholders to go beyond Stage 8.

The revised code was to be submitted to the National Energy Regulator of South Africa “within the next few days” for adoption.

Padayachee’s statement came several months after Eskom former acting head of generation Thomas Conradie told media that a workgroup comprising Eskom, its System Operator, and industry stakeholders was revising the Code of Practice.

Vally Padayachee, NRS Association chair

“There has been a lot of consultation, but we need to now put a stop date on it for the sake of the grid,” Padayachee said.

“We cannot guarantee that in winter, we will not go beyond Stage 8.”

The load-shedding Code of Practice is crucial for implementing rotational power cuts.

Without instruction for what to do beyond Stage 8, municipal electricity distributors would have to use their own operating procedures to protect the national grid.

“In that environment, the propensity for human error is possible,” said Padayachee.

The Code of Practice for load-shedding stipulates an amount of megawatts that must be shed to ensure the power utility can meet peak demand and protect the integrity of the national power grid.

Failure to follow the code, or the absence of the code, could result in the grid frequency fluctuating too much above or below 50Hz — the frequency that keeps the grid alive.

This could result in a total grid collapse, plunging South Africa into darkness for an extended period. Restarting the grid is difficult and time-consuming, and South Africa could be without power for one to two weeks.

South Africa on the brink of higher load-shedding stages

Eskom’s explanation of the proposed new load-shedding Code of Practice comes after MyBroadband enquired whether South Africa was on the verge of Stage 7 load-shedding.

This was after Eskom’s evening peak statistics showed that it was relying extensively on emergency power generation and was at the maximum stage of load curtailment.

Eskom uses load-curtailment to reduce demand on the grid from energy-intensive users in the country, such as miners and smelters.

These customers get compensated financially for their participation and can be exempted from Stage 1 and Stage 2 load-shedding.

We asked the power utility what would happen if further losses in generation capacity were to occur, seeing as though it was already running 19 open-cycle gas turbines (OCGTs) in addition to Stage 6 load-shedding and Stage 4 load-curtailment.

Stage 4 is the highest level of load-curtailment at the power utility’s disposal, and further breakdowns would likely mean that Eskom has no option but to increase load-shedding or risk a grid collapse.

Eskom explained that the System Operator ensures there are reserves available at all times to respond immediately to unforeseen events such as a generator trip.

“In the event that a sudden trip of multiple generators occurs, beyond the reserve capability, there are automatic protection schemes in place to automatically reduce demand and normalise the power system. This happens in less than 1 second,” Eskom assured.

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Eskom proposes Stage 16 load-shedding schedules