Delay using your inverter – Eskom

Eskom is asking consumers to delay starting up inverter and battery systems when electricity returns after load shedding to avoid a demand peak after every planned blackout.

Such peaks can destabilise the system and result in trips.

Inverter and battery systems, installed in many households to supplement the limited power supply from Eskom, assist consumers by keeping on limited lights and appliances during load shedding.

During Stage 6, which in recent weeks was a regular occurrence, consumers endure up to 10 hours a day without electricity.

Winter power

At these high levels of load shedding, it is already becoming a challenge to get batteries charged during limited hours of electricity supply, but Eskom lists delaying the start-up of these systems as something consumers can do to protect the country’s electricity supply and reduce the stages of load shedding necessary to get through winter.

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Less capacity than last winter

During its State of the System briefing on Thursday (18 May) Eskom made it clear that the coming winter is going to be extremely difficult, with Stage 7 or 8 or load shedding daily unless it succeeds in limiting unplanned outages of its generation fleet.

Three units at its youngest power station, the 4 800MW Kusile Power Station near eMalahleni in Mpumalanga, are out of service following a chimney collapse. They are only expected to be back online by year-end, and even then, will not be running at full capacity.

In addition, the steam generator replacement to extend the life of Koeberg Unit 1 has been delayed. It is only expected to return to service in September.

This means Eskom is approaching winter when electricity demand is at its highest with about 3 000MW less generation capacity than last year.

The utility shared three different winter scenarios.

The most optimistic will be if it can contain unplanned outages to 15 000MW, but even then, Eskom expects up to Stage 5 load shedding almost every day in May, July and August and up to Stage 3 for 18 days in June.

However, in recent weeks unplanned outages exceeded 19 000MW on more than one occasion and on Sunday (21 May) was still 16 486MW, according to Eskom.

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Unprecedented levels of power cuts

Eskom notes that unplanned outages often vary by up to 4 000MW.

The utility expects daily Stage 6 load shedding during May, June, July and August if breakdowns increase to 16 500MW.

But if the loss of generation capacity increases to 18 000MW, consumers are expected to experience up to Stage 7 load shedding daily during May/June and Stage 8 in June/July.

Eskom has never intensified load shedding beyond Stage 6.

Even these forecasts seem optimistic though, since they are based on electricity demand of up to 32 572MW, compared to the peak demand last year of 34 000MW and Eskom’s own statement that the coming winter is expected to be exceptionally cold.

Eskom expects that it will only be able to supply about 26 500MW, despite the fact its installed capacity is almost 48 000MW.

To reduce the gap of about 7 500MW between demand and supply with as little as possible load shedding the utility will, as it usually does during winter, reduce planned maintenance to between 1 300MW and 3 000MW. The open-cycle gas turbines will run at a 20% load factor, compared to 1% before the electricity crisis.

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Incentives to reduce demand

The only other available mechanism is to manage the demand.

Eskom already has programmes that incentivise industrial users to reduce demand during winter, and these will be extended.

It gains about 270MW when the power alert is flighted on television to ask for demand reduction, and it plans an aggressive media campaign to convince consumers to “only use what you need”.

It is against this backdrop that Eskom is now asking that consumers delay switching on their inverter systems after load shedding.

Experts in the alternative energy space told Moneyweb that large sun and wind farms switch automatically when they detect abnormalities or instability on the network.

Eskom’s call would therefore be aimed at household installations.

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Alternative solutions 

Jan-Hendrik Kruger, director at Nuvo Energy, which provides alternative electricity systems, agrees. He says in theory Eskom is correct, but the same goes for geysers and other appliances that add to the load when supply returns after load shedding.

Geysers in fact use more electricity that the average household inverter system, he says.

It would therefore be more effective to encourage consumers with tax breaks or other incentives to install controllers on their geysers to delay switching it on by 10 or 15 minutes, he says.

Another option, says Kruger, would be to stagger the switch-on at substations to avoid switching on the whole area it services at all once and thereby avoid a post-load shedding peak.

This article originally appeared on Moneyweb and was republished with permission.
Read the original article here.