Hawaiian Electric Co. has not found the smoking gun—or charred power line—yet, but the company says there is convincing evidence that lightning was the culprit in the Dec. 26 islandwide power failure.

 

  HECO Says Lightning Caused Outage

 

  HECO Executive, Robert Alm says a third strike of lightning tripped off all three lines on a tower between Oahu two biggest plants. 

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  There were at least five strikes on transmission lines within 20 minutes, each causing short circuits in the system that carries electricity from the Kahe and Waiau plants to East and Central Oahu, said HECO Executive Vice President Robbie Alm. The worst strike happened in the Aiea area, knocking out all three power lines between Waiau and Kahe, “;a very big blow to the system because it connects the two biggest power plants,”; Alm said.

“;The bottom line is that severe and unusual lightning strikes caused multiple short circuits, resulting in system instability,”; he said.

Alm said the company will bring in experts on lightning and transmission and generation equipment to analyze the multiple blows, which led the Oahu power grid to shut down. The investigation is expected to cost up to $1 million, he told reporters yesterday at a news conference.

The three-line strike had an immediate impact on customers, causing lights to flicker and elevators and air-conditioning systems to shut down. It triggered an instant 150-megawatt dip in power use, a factor in destabilizing the system, which was cranked up to meet the 1,100-megawatt demand on that busy holiday-season night.

“;If there was a knockout blow, that was the knockout blow,”; Alm said.

Within 10 minutes, automatic equipment-protection systems closed down seven generators at Kahe, Waiau and the privately operated HPOWER plant and AES coal-fueled plant at Campbell Industrial Park.

“;The blow into those seven power plants is more than can be dealt with by the system. The system tries to hold on, the load-shedding schemes try to stop it, but too much has gone wrong,”; Alm said. “;It's like a fighter who received a big blow but is still standing. But all you need to do is tap him and he will go over.”;

Alm said crews have checked transmission towers and lines from helicopters and on foot and have not found any visible damage from lightning, but have ruled out other possible causes.

“;There are no problems with the structures; all the shield wires are intact; there are no foreign objects on the wires,”; he said. “;We have to believe it is evidence of lightning strikes. People have said finding the exact place on a wire where lightning hits is like finding a needle in a haystack. It impacts on the inside but does not show on the outside.

“;We know from the way our relays were hit where these things happened.”;

Alm faced questions about why it took so long to restore power. He said nearly 200 customers have filed claims.

“;One of the reasons is that it took place at night,”; he said. “;We could not use the transmission lines that were closed down because we couldn't tell if they were severed. We had to wait until daylight—we didn't energize them until we could do a flyover.”;

Oahu's generator plants produce electricity through steam turbines, which have to be restarted cold. Combustion turbine systems in use elsewhere, which Alm compared to a jet engine, are quicker to restart, he said, “;but it is vastly more expensive to run and the rates would be significantly higher.”;

HECO will start its first combustion turbine plant in Campbell Industrial Park in July, which “;will be able to ramp up a load in a single unit faster than anything we have and probably will make it quicker to energize Kahe plant,”; Alm said.