high voltage direct current
high-voltage direct current (HVDC) link connects the power systems of New Zealand’s North and South Islands. The capacity of the link is 1040 MW and it operates at voltages of 270 kV and 350 kV.
The link generally sends power from the South Island to the North Island. Power is converted from alternating current (AC) to direct current (DC) at Benmore in the Waitaki Valley, then transmitted over 535km to the shores of Cook Strait, where undersea cables carry the power 40km to the North Island.
At Haywards in the Hutt Valley, the power is converted back from DC to AC and injected into the National Grid.
The HVDC link was commissioned in 1965. It won the Institute of Professional Engineers of New Zealand (IPENZ) Millennium award recognising achievement in energy and is an important part of New Zealand’s engineering heritage.