Transpower boss warns of more disruption

Patrick Strange. Photo / Steven McNicholl

Transpower chief executive Patrick Strange has warned consumers to be prepared for more failures on the national grid while it is being substantially rebuilt during the next three years.

There have been three major outages in the Auckland area during the past two years and Mr Strange said that during the $3.5 billion upgrade the system would be especially vulnerable.

"It takes a long time to build things - the question is that for the next three to four years can we guarantee supply. Of course we can't," he told the Power and Electricity World Conference in Auckland yesterday.

"We're doing everything we can to avoid them but obviously when you're doing that much work on a network that is so stretched if we get to 2013 without some more I'll be very surprised."

Foundation work was now under way on the new $820 million transmission line running through the Waikato to Auckland which is scheduled to be finished in 2013, the $670 million Pole 3 interisland cable project was due for completion in 2012 and the $470 million alternate line north of the Harbour Bridge could be finished as early as 2013, in spite of a delay in being approved.

Investment in the grid stalled a decade ago when it was envisaged localised generation would negate the need for leading to the big catchup investment.

Strange said events cascaded into major failures in October when a fork hoist caused lines to flashover in South Auckland, causing blackouts north of Henderson.

That occurred on one of the three days a year that other lines that could have taken the load were down for maintainence.

A fire beneath lines in Waikato led to rolling cuts in Auckland and Northland last month when a minor line was out for maintainence but at a time when the wider system had to be protected from a big electrical storm.

Statistical modelling did not appear to be allowing for everything that could possibly go wrong, Strange said.

"Time and time again we're getting these chains of events all around the world - we must have got the maths wrong."

The conference heard a A$32 billion ($40.6 billion) grid upgrade was under way in New South Wales and Queensland.

Paul Simshauser, chief economist at Australian renewables generator AGL, said despite a surge in retail prices in NSW in 2007, they still remained well below those here due to generation from relatively cheap coal, plentiful gas and lower transmission costs due to the scale of the grid.