Transpower removes lines from service during severe solar storm (Updated – Emergency over)

Update, 8am Thursday Nov 13 – Emergency over.

Transpower issued a grid emergency notice this afternoon and removed some South Island electricity transmission lines from service as a severe geomagnetic storm reached New Zealand.

The grid operator took the precautionary action in response to the onset of a G4-classified geomagnetic storm, which poses risks to critical electrical infrastructure.

Removing the circuits from service does not impact consumers’ electricity supply but represents an important step to prevent damage to critical equipment should the solar storm intensify, says Transpower.

The company says it will issue further operational notices either when the storm passes to remove the grid emergency or to provide additional information should the situation change materially or further actions be required.

Space weather monitoring

Transpower monitors not only weather in Aotearoa but also weather in space that can affect the power system.

Space weather occurs when the Sun ejects plasma and other matter in Earth’s direction through coronal mass ejections (CME), which are rare events that most people won’t notice because the planet’s magnetic field shields us from the particles.

However, these CMEs can cause geomagnetic storms on Earth, and these storms can send unwanted currents through the long electricity circuits that Transpower manages.

When the currents reach transformers in substations or large hydroelectric dams, they have the potential to cause extensive damage, says the company.

To minimise the risk of damage to critical equipment, Transpower may work with industry to switch off some parts of the power system temporarily during extreme solar storms.

“These events are rare, but we are prepared for them and have a plan in place,” the company says.

If preventive action is not taken and equipment is damaged, it could require expensive and time-consuming repairs or the total replacement of equipment, says Transpower.