Inside Eskom's national control centre

The control centre is classified as a national key point, so security is tight and no cellphones or cameras were allowed into the building when a small group of journalists entered it to tour the facility last week. They met at 4pm, about an hour before the peak demand from the grid begins.

System operator general manager Robbie van Heerden was the host to show the group around and explain how the control centre monitors electricity and tries to keep the power supplies stable.

"Whatever Gauteng does, affects demand across the whole country. If you can keep Gauteng's power managed the rest of the country is fine," he said. "It can be freezing in the Western Cape [but] conditions there won't affect us that much. When demand is unusually high, 90% of that load comes from Gauteng," he said.

Eskom generates 95% of electricity in South Africa an amount that is equivalent to 45% of all the power used on the African continent. Eskom sells its power to, and buys electricity from, several countries in the Southern African Development Community, but in most of the neighbouring countries' demand is really quite low.

Maintaining a balance

Van Heerden said the toughest job for the engineers and technicians in the centre was to ensure a continuous balance between supply and demand. For them the difficulty begins at about 5pm when people start streaming home from work, switch on heaters, lights, geysers and stoves.

Each of these events increases the demand on the national grid but then, at about 6pm, the industrial consumers respond to the peak tariffs that are charged during the hours of six and nine at night. So they reduce their consumption for a few hours, allowing network to stabilise.

Inside the control room where the electricity balance is monitored and maintained, a huge screen the size of those used in a movie theatre, lists rows and rows of figures that constantly change as supply and demand data is updated dynamically. The data on the screen lists the working power stations, the amount of power being generated and the amount of power being used.

On the right side of the giant screen, a map depicts the country's transmission system where the frequency of the supply across the country is displayed as engineers try to keep the optimal balance between supply and demand at about 50Hz.

To show how dynamically and rapidly the electricity demand is, Van Heerden points out that when the group started monitoring demand at 5.20 that afternoon, folk around the country were getting home switching on their appliance at preparing supper. At that point the load was 31,666MW and then, just 12 minutes later, as electrical current was drawn from the plug sockets, the load reached 32,356MW.

It would keep climbing until the industrial consumers reduced their consumption because of peak tariffs from 6pm and as they did so, the national grid would stabilise once again.

The control room has six engineers together with technicians who each work a 12-hour shift. Before a team member is appointed, a special evaluation is done on the individual's ability to handle stress because working in the control centre is stressful and needs constantly cool heads.

Asked about load shedding and power cuts, Van Heerden insisted that Eskom was doing all it could to prevent these and so far it had managed to do so. He says that some consumers blame any sudden power cut on load shedding when it is not the case and the fault has most often been caused by a problem at a sub-station, a fault in the distribution network or even by thieves stealing electrical cables in another part of town.

"Most of the time, power failures have little or nothing to do with Eskom, or the crew in this control room," Van Heerden said.

Source: Sapa via I-Net Bridge