Tech trial aimed at boosting power line resilience

Powerco is trialling new technology at 10 sites across its electricity network to work out how aeolian vibration affects its power lines.

Over time, vibrations from certain types of wind can damage power lines – ultimately causing the conductor to fail at the bonding point and fall to the ground. Not only does it cut power to customers, it’s also a serious public safety risk as the lines could still be live after they have fallen, Powerco General Manager Electricity Karen Frew says.

It’s hidden damage, with the conductor deterioriating from the inside out. By the time it causes failure of the line, it’s too late – the line is on the ground.

Powerco is using new solar-powered technology called Sentrisense, provided by Identimark, for the trial. The device is attached to the power line and measures vibrations. A weather station is attached to the nearest power pole to the device to capture localised weather data.

“In the distribution industry, we’re working to understand the engineering around how aeolian vibrations affect our networks. It’s exciting research. As far as we are aware, no other electricity distributors in New Zealand or Australia are doing this,” she says.

The occurrence known as aeolian vibration is produced when a low-velocity wind flows over power line conductor at a 90-degree angle. The energy from the wind flow is transferred into the conductor which starts to vibrate.

“It normally happens on a cold, frosty morning. The slow winds come over the lines, which starts the vibration. This makes the conductors contract and get really tight,” she says.

Modelling of its electricity network enabled Powerco engineers to narrow down the trial to 10 sites – three in Taranaki, two each on the Coromandel Peninsula, Manawatū-Whanganui and Waikato, and one in Wairarapa.

“What we want to do is see if aeolian vibration is happening on our network and where it’s happening, so we can start putting vibration dampers on affected sections of lines to counteract it – before the line falls,” she says.

With around 28,000km of power lines across Powerco’s electricity footprint, it would be inefficient and cost prohibitive to put damper devices on all its power lines.

The trial will run for 12 months.

Below: A power line fitted with a Sentrisense device. A weather station mounted to the pole.