Eskom explains sudden load shedding changes – and why suspensions don’t always last

 ·2 Feb 2024

Power utility Eskom says that load shedding suspensions aren’t coming as a result of political or any other pressure, but rather as a response to the fluctuations and shifts in supply and demand at any given time.

And the reason these suspensions don’t always last – or shift back to load shedding very suddenly, as was the case last week – is that things can change very quickly, and the National Control Centre needs to take the necessary action to protect the grid.

South Africans have become accustomed to frequent changes in load shedding over the past few years, but in recent weeks, shifts in stages have been quite dramatic, swinging from no load shedding to permanent stage 2 or stage 3 outages at short notice.

Other times, Eskom has suspended load shedding overnight without even announcing it, only to return to outages again in the morning.

This has been happening when user demand on the grid has hit record lows, and Eskom’s maintenance regime has hit unprecedented highs – raising eyebrows among some analysts.

However, Eskom has cleared the air around these haphazard changes, saying that it is simply doing what it must to stabilise the grid and protect it from collapse.

Responding to queries this week, the power utility said that, given the inconvenience and hardship that load shedding causes individuals and the damage it does to the economy, it does face pressure – internally and externally – to keep load shedding to a minimum.

But load shedding is not used as a “selective response”, it said, but as a response to protect the grid from collapse.

“Eskom’s number one priority is to prevent a total system blackout, and load shedding is a last resort lever to do so. At the same time, Eskom endeavours to minimise the level and frequency of load shedding but will not do so at the expense of an unacceptable risk to the system.

“Thus, any changes to either the expected demand or availability of the generation fleet could necessitate a change (either up or down) in the required level of load shedding to ensure the stability of the system,” it said.

Eskom said it also endeavours to notify the public well in advance, but this is not always possible.

Load shedding suspended – then not

Referring specifically to the recent spate of load shedding suspensions (and haphazard changes to the schedule), Eskom said that it has been able to suspend outages at short notice during some periods of low demand and the return of units that were out of service.

This happens mostly overnight, and during the mid-afternoon on weekends, it said.

“The demand for electricity varies constantly, with high demand during weekdays, particularly in the morning and the evening and it is also influenced by the sudden changes in the weather patterns, which impacts the availability of solar PV generation.

“The National Control Centre monitors the demand for electricity as well as the available supply to balance this demand. This is done every minute of every day and adjusted as needed,” it said.

However, there are certain conditions where the grid might lose “flexibility”, and sudden reversals have to be made.

“For example, the lack of flexibility during the planned outage of Ingula Power Station removed 1,330MW of generating capacity and 1,480MW of pumping capacity from the power system.

“The Ingula pumped storage scheme provides the System Operator with fast start, fast ramp, and fast shutdown capability that is used to manage the continuous fluctuation in demand. In other words, 2,810MW of very flexible generation capacity was not available to manage the demand fluctuations.

“Without this flexibility, load shedding stage changes were required to maintain the stability of the power system, particularly during low demand periods,” the group said.

Improving performance

Addressing concerns about the performance of the grid in 2024 versus 2023 – when the situation was dire – Eskom said that it has more wiggle room in 2024, with lower levels of breakdowns as well as more generating units giving power to the grid.

The utility said that since January 2023, unplanned losses have improved by about 5%, and various initiatives have helped with its Generation Operational Recovery Plan.

These include:

  • Kusile Units 1, 2, and 3 were brought online earlier than planned, bringing 2400MW into the grid.
  • Kusile Unit 5 was synchronised for the first time into the Grid, bringing 800MW into the grid.
  • Implementation of load limiting and the first-ever town load curtailment.
  • Launch of the largest Battery Energy Storage System, first of its kind in South Africa and the African continent.
  • Installation of 20 clean energy Microgrids.
  • Demand Side Management Initiatives.

Eskom said that this wiggle room has enabled the group to do more planned maintenance, which it says is essential for sustainable performance improvement.

“Eskom has also committed to keep load shedding below or at Stage 4 in the summer months as a result of the realisation of some of its actions as per the plans stated above,” it said.

Read: Eskom expands load limiting in Gauteng

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