Proposal to upgrade HVDC link submitted to Commisn
Half-billion dollar proposal to upgrade inter-island HVDC link submitted to Electricity Commission - 03 Oct 2005
Transpower has submitted to the Electricity Commission an investment proposal for increasing the capacity of the high voltage direct current (HVDC) link between the South and North Islands.
The intention is to increase the maximum capacity of the HVDC inter-island bipole link from 1040 megawatts to 1400 megawatts, by 2010. The estimated capital cost of the project in current dollar terms is $520 million.
The work will involve the decommissioning and replacement of the 40 year old mercury arc valve technology associated with Pole 1 of the bipole link. This equipment is located at the Benmore substation in the South Island’s Waitaki Valley, and at Haywards substation near Wellington.
Pole 1 will be replaced with a new 700 MW thyristor pole, similar to the Pole 2 equipment commissioned in 1991. The project also involves the laying of two additional submarine cables across Cook Strait.
Transpower Chief Executive Dr Ralph Craven says the original mercury valve equipment commissioned in 1965 has served New Zealand well, but is now the last remaining technology of its type in use anywhere in the world.
“The HVDC link is a vital part of Transpower’s network, enabling a national electricity market and efficiently balancing power supply and demand between islands for the benefit of all New Zealanders. It is also a sustainable alternative to the increased generation that would otherwise be required in both the North and South Islands. However, it needs to be a reliable link, and the 40 year old mercury-based technology associated with Pole 1 is progressively falling short of the reliability and availability standards that we require of a 21st century power system.”
Dr Craven says the documentation provided to the Electricity Commission summarises the work Transpower has done on the project to date. It includes the reliability and economic imperatives for the investment and a cost-benefit analysis of having the 1400MW capacity in service by 2010.
The HVDC upgrade proposal is part of the first Grid Upgrade Plan (GUP) that Transpower is submitting to the Electricity Commission.
The GUP also includes the North Island 400 kV Project (which was initially submitted to the Commission in May 2005), a comprehensive plan for asset management and operation of the grid, and information on contracted investments. Transpower is currently finalising a further volume of the GUP, detailing an extensive programme of regional upgrades.