Eskom put hopes on return of units to reduce pressure on the system.
By Lehlohonolo Lehana.
Eskom notes that the national electricity grid remains constrained, with an elevated risk of load shedding over the winter period, particularly during the morning and evening peaks.
During the next few weeks, however, the power utility said that it will return to service two units at Kusile Power Station, and Koeberg Unit 2 is expected to return by the end of June 2022. These three large generation units will add approximately 2,500MW to the power system, it said in a presentation on (11 May).
"Unit 2 of the Koeberg Nuclear Power Station, together with the two-generation units expected to return to service following the modification and correction of the design defects on one unit and repairs to the Flue Gas Desulphurisation technology on the other unit at the Kusile Power Station, will significantly ease the pressure in time for the high winter demand."
"These Kusile units will add a combined 1,600MW to the power system, while Koeberg 2 will add another 920MW when it returns to service by the end of June."
Since January, Eskom said it has had to operate with only a single unit – or half the capacity – of Koeberg, while the other unit has been undergoing routine refuelling and other Long-Term Operation activities.
Added to Koeberg's capacity being offline for this period, Eskom said it has also had to cope without the 794MW normally contributed by the damaged Unit 4 of Medupi Power Station. Together, these two units are responsible for the implementation of almost two stages of load shedding.
"As Eskom grapples with load shedding and other operational challenges, we remain committed to the principles of openness and transparency about our operations.
"As such, the State of the System update, the Eskom Data Portal and the regular media briefings give us an opportunity to provide insights about the state of the power system and keep South Africans and all stakeholders informed and enable them to plan ahead, are consistent with this commitment accountability, "said Eskom Group chief executive, André de Ruyter.
Due to low plant availability, Eskom has increasingly relied on the usage of diesel-powered open cycle gas turbines (OCGTs) to limit the implementation of load shedding. From 1 January to 10 May this year, load shedding has been implemented for 32 days. This is six days more than the 26 days of load shedding during the same period last year.
The increase in the implementation of load shedding came on the back of higher levels of unplanned plant breakdowns, which averaged 26% of the fleet in the period ended March 2022. During this period, the energy availability factor (EAF) averaged 62%, the state firm said.
"Planned maintenance is Eskom's only weapon to try bring reliability and predictability to a neglected plant," said Eskom chief operating officer, Jan Oberholzer.
"To create space to effectively execute on the Reliability Maintenance Recovery programme while fully powering a growing economy, South Africa desperately needs additional generation capacity of between 4,000MW and 6,000MW.
"With power stations reaching the end of their operational life, the gap will only increase. Bringing on new capacity onto the grid as soon as possible is therefore critical and requires an SA Inc. approach, "he said.
Long-term solutions were implemented on coal handling to effectively address coal-stock challenges which have long been a contributing factor to poor plant performance. Coal stock levels are healthy with an average of 38 days' worth, excluding Medupi and Kusile. Coal stocks jump to an average of 77 days’ worth of stock when those two are included.
Significant progress is also being made in the completion of the new build Kusile Power Station, the group said. Unit 4 achieved full load of 800MW on 11 January 2022 and successfully accomplished the 30-day reliability run on 27 April as commissioning tests continue towards commercial operation.
The unit was first synchronized to the national grid on 23 December 2021 and is on course for commercial operation by July 2022.
Modification and correction of the major design defects on the boiler plant at Medupi have been completed, Eskom said. “This has significantly improved the performance of the power station, helping to limit the implementation of load shedding,” it said.
Medupi's energy availability factor (EAF) rose to 67% by the end of April 2022, up from 46% in April 2020, before the modifications.
"Each of the six generation units had to be switched off for 75 days to perform this work. This will indeed prove to be a worthy sacrifice for the people of South Africa, who have had to endure long hours of load shedding in order for Eskom to correct these poor designs," said Oberholzer.
"This consistently higher EAF is the clearest testament to the correctness and accuracy of the agreed technical solutions and the corrective work of what had hobbled the performance of the power station."
Medupi and Kusile
Eskom said it expects both Medupi and Kusile to form the backbone of an evolving and greener power system that will be able to take South Africa into a more sustainable and dynamic energy industry.
Similar technical corrections to the design defects of the first two units of Kusile Power Station have also been successfully concluded, the last one (Unit 2) having been completed during May. Corrections to the design defects on Unit 3 are currently underway, it said.
The Koeberg Nuclear Power Station continues to operate efficiently and within the required safety parameters, the state company added. Unit 1 has been operating without interruption for 196 days since its last refuelling and maintenance outage.
"Apart from the postponement of the Steam Generator Replacement (SGR) on Unit 2 due to the significant risk to the grid posed by delays in carrying out the SGR installation according to the outage plan, other maintenance and refuelling outage activities, including the replacement of the reactor vessel head, are progressing as planned.
"The unit, which produced electricity for 454 days without interruption ahead of the January 2022 refuelling and maintenance shutdown, is expected to return to service by end June 2022, which will add a great boost to Eskom's efforts to reduce load shedding and meet the high winter demand. The SGR on this unit has been postponed for the outage next year."
Eskom said that the Koeberg Long-Term Operation (LTO) activities to enable Koeberg to operate for another 20 years beyond 2024/25 are underway. Eskom will by June 2022 submit the required supporting documentation to the National Nuclear Regulator (NNR) for evaluation.
Eskom's group executive for Transmission, Segomoco Scheppers, highlighted that the outlook shows an elevated risk of load shedding remains. "One thing counting in favour of the country is the world-class and effective management by the transmission system operator, whose main task is to maintain the balance between supply and demand," said Scheepers.
In executing its duties, the System Operator will, unfortunately, continue to rely on the usage of the Open Cycle Gas Turbines, which burn expensive diesel to mitigate the impact of load shedding. The distribution system continues to provide good and sustainable performance, it said.
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Video Courtesy of ENCA.