File photo: Siphiwe Sibeko
File photo: Siphiwe Sibeko

Good news in a very dark week

By Craig Dodds Time of article published Apr 18, 2015

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Cape Town - A whole week of load shedding, twice climbing to the dreaded stage 3, incredibly has a silver lining: Eskom is getting lots of practice in crisis-managing the grid.

That’s the view of energy expert Chris Yelland, who agreed with Public Enterprises Minister Lynne Brown’s assessment that the country was nowhere near a total blackout.

Brown gave an update on the grid in Parliament on Wednesday and, in a detailed written reply to a parliamentary question from the DA’s Nosimo Balindlela, spelled out the protection measures in place to avert a devastating collapse of the grid that could take as long as two weeks to fix.

Brown said in the reply that emergency drills for a “major incident on the national power grid” were done every year at provincial level, involving simulation exercises at specific locations.

There were also national simulation exercises annually, testing Eskom’s response to a national blackout.

It had two “black start” facilities which each had to be tested for their ability to start a unit and restore power to a section of the grid every six years.

Yelland explained that these black start facilities were needed because power stations, before they could begin producing power themselves, needed electricity for functions like fans, conveyors and pumps.

Once one generator was back in operation, it could supply electricity to start the next one, and they could progressively be brought back online.

Brown’s reply showed that “at an operational level, at this emergency level, Eskom is pretty well prepared”.

Yelland said grid failure happened when supply and demand were thrown out of balance by a sudden event.

“You have generators of electricity and users of electricity, and because electricity cannot be easily stored, supply and demand have to be in balance at all times. So if demand increases you have to increase supply,” Yelland said.

In a constrained system like ours, if nothing was done to reduce demand – by load shedding for example, and it exceeded supply for too long, generators would become overloaded and eventually one would trip.

That would increase the gap between supply and demand even further, tripping more generators in a “cascading effect” until the whole country had lost power.

Fortunately, Brown’s reply showed there were multiple layers of protection to prevent this.

Political Bureau

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