By Tumelo Modisane, tel: (012) 314 2404

The National Electricity Regulator (NER) has instructed Eskom to report on the causes of widespread electrical power interruptions that occurred during November.

Eskom has also been told to come up with measures to reduce the likelihood of these interruptions happening again.

“The present capacity to supply the load in the Western Cape depends on the availability of the local generation as well as the transmission system that connects this network to the generation pool in Mpumalanga,” says Nhlanhla Cebekhulu, head of communications and stakeholder management at the NER.

In all three incidents during November the local generation, which consists basically of the Koeberg power station, was not available.

“The one generator at Koeberg was out on planned refueling while the loss of the second Koeberg generator was unplanned, and was apparently triggered by failure of equipment on the transmission system on two of the occasions,” said Mr Cebekhulu.

This loss of 1 800 MW of generation capacity affected the transmission system, and some load had to be interrupted to prevent the electricity system from a cascading collapse.

The NER says it’s aware that Eskom is in the process of increasing the transfer capacity of the transmission system as well as installing additional generating capacity in the Western Cape.

The completion of these two projects, says Mr Cebekhulu, will ensure a significant improvement in capacity to supply the load.

The NER has also recently audited the Western Cape network strengthening scheme, and has concluded that “the methodology and phasing of the projects are in line with the investment criteria that [the NER] has agreed upon” with Eskom.

One of the NER’s roles as regulator is ensuring that Eskom provides customers with an appropriate level of supply reliability.

This means that the cost of providing the supply needs to be balanced with the economic impact of the interruptions.

“The recent spate of system events is not unique, but the number of events has been high,” said Mr Cebekhulu. ”Furthermore they occurred at the low end of the investment cycle, just prior to the next phase of strengthening.”

He says the regulator will put pressure on Eskom to ensure that the chances of failure of equipment is minimised.

He added that the NER is in the process of introducing a system of penalties or incentives for Eskom for the reliability performance of the transmission system from next year onwards.

“We will also be conducting our first independent technical audit on the transmission business during the course of 2006,” he said.

He concluded that by 2007 “the system will be capable of handling similar events to a much better degree after the completion of the transmission and generation projects”.

The NER will continue to be responsible for electricity until 31 March next year.

From 1 April the recently-launched National Energy Regulator of South Africa (Nersa) will regulate the electricity, piped-gas and petroleum pipeline industries. - BuaNews