Transpower safeguards inter-island link

31 March 2020

Transpower celebrated an early return to maximum capacity for the High Voltage Direct Current (HVDC) link on Saturday, following a lengthy period of reduced capacity to carry out essential project and maintenance work.

The HVDC link connects New Zealand’s electricity supply and demand centres. It is the vital electricity transmission line that allows the South Island’s renewable hydro electricity to supply the North Island, and the North Island to send power to the South Island when water levels are low.

Beginning in early January, Transpower undertook a demanding programme of work on the HVDC network to improve the resilience and security of this critical component of the national grid for the future.

General Manager Grid Delivery Mark Ryall said the programme was already well advanced when it became evident that the outage should be concluded as soon as possible, in response to COVID-19.

“The work was originally planned to conclude on 9 April, but we had successfully achieved all critical components of equipment replacement, reconductoring, and testing so were able to return the link to full capacity almost two weeks early.

“This is a huge positive for all New Zealanders as the capacity limit for transferring electricity between the North and South Islands is now raised to normal levels, enabling the system to operate without constraints.”

General Manager Operations John Clarke said planning for the work which began as far back as 2016 involved considerable interaction across the electricity industry by Transpower in its role as System Operator.

“This coordination and information sharing allowed the HVDC work to proceed, while ensuring security of electricity supply and enabling orderly trading in the wholesale electricity market.

“Such a lengthy outage has a significant impact on the industry including generators and large industrial customers. The challenge of coincident gas field maintence resulting in restricted gas availability for electricity generation was also successfully addressed. We are grateful for the support those organisations have shown.

“This outage has been a model for industry coordination for future outages to enable major maintenance with on the power system,” he says.

Mr Ryall says: “During this period, we successfully completed major work to replace the HVDC lines through Churton Park in Wellington, the control systems at Haywards and Benmore substations as well as annual maintenance and detailed condition assessments.

“We want to thank all the suppliers and service providers who have worked tirelessly to ensure our inter-island link can provide a secure and reliable service into the future.”



For further information, please contact:   

Corporate Communications Team, 021 195 8613.