Gauteng at the heart of SA power

2013-07-28 20:19
 (File, Duncan Alfreds, News24)

(File, Duncan Alfreds, News24)

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Johannesburg -  A one-degree Celsius drop in temperature in Gauteng alone can add an extra 400MW or more onto the country’s electricity demand.

This emerged from a tour of Eskom’s National Control Centre in Germiston, organised by the parastatal for the media.

The control centre is classified as a national key point, therefore, security is tight.

No cellphones or cameras are allowed in.

A small group of journalists toured the centre, entering at 16:00, an hour before the peak in demand begins.

System operator general manager Robbie van Heerden was the main host.

"Whatever Gauteng does, affects demand in the whole country. If you can get Gauteng managed we'd be fine," he said.

"It can be freezing cold in the Western Cape [but] it won’t affect us that much.

"When demand is unusually high, 90% of the additional load comes from Gauteng," he said.

Koeberg power station supplies 50% of the power in the Western Cape.

Eskom generates 95% of electricity in South Africa. This is equivalent to 45% of the power used in the African continent.

It also sells to and buys electricity from countries in the Southern African Development Community.

However, most of the neighbouring countries' demand is quite low when compared to South Africa, some as low as 100MW.

Van Heerden said the toughest job was to ensure a continuous balance between supply and demand.

The most difficult time begins at 17:00 when everybody comes home from work and starts cooking, turning on their geysers, lights, and heaters.

This changes at 18:00, when industry responds to peak tariffs and reduces their production for a few hours. This gives some relief of up to 800MW.

Inside the control room it’s a different environment.

A huge screen the size of a movie theatre's is on display, with figures changing every minute.

The screen has a list of all the power stations on the grid. Each unit in each power station that is working and supplying power is displayed by a red dot. Units which are off-line are displayed in green.

Adjacent to that display is the amount of load the station is delivering and next to it the station's capacity.

At the bottom of the screen is a display of the total amount of the load and the capacity available.

On the right side of the giant screen is a map showing the country's transmission system.

A small digital screen is posted on the top right corner displaying the time and the frequency.

The engineers have to keep the frequency at 50 Hertz (Hz), as it represents the balance between the demand and supply.

Van Heerden said if the number was maintained at 50Hz the balance between demand and supply was optimal.

"We don't want to go below 49.8Hz," he said.


But winter is not the most difficult time for Van Heerden and his team of engineers. Summer is.

The reason is that the difference between what is needed and what is available is small, which leaves less room for the engineers to manoeuvre.

The actual control room has six engineers together with technicians who work a 12-hour shift.

The team is tested both physically and mentally before starting their career in the control room. It is made up of young engineers and seasoned ones with experience of over 20 years.

To ensure that the appropriate people work in the heart of South Africa's national power control centre, the team is also tested on their aptitude.

They are assessed on how they can handle stress.

"It is not a place for soft people. You have to remain calm and handle all situations properly," he said.

Despite the increase in demand, as it is winter, Van Heerden insisted everything was being done to prevent organised power cuts.

However, he took some time to explain the process.

When the grid is under pressure, municipalities who distribute power to homes are notified that the situation is bad.

Municipalities are then informed of how much electricity they will need to reduce.

They then design a schedule for themselves which is communicated to the residents of the area which will experience the power cuts.

A sudden power cut in some suburb should not be interpreted as Eskom going back to staggered power cuts.

"It could be maintenance in that particular area and has nothing to do with Eskom load shedding."

Another option used by Eskom is to get aluminium smelters to reduce demand. This process is within the contract that Eskom has.

Read more on:    eskom  |  energy

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