page_title: Electricity sector in New Zealand
section_title: HVDC Inter-Island
hierarchical_section_title: Electricity sector in New Zealand / Transmission / HVDC Inter-Island
caption_attribution_description: English: HVDC Pole 2 thyristor valve hall at Haywards in the New Zealand HVDC Inter-Island scheme, during a maintenance shutdown
context_page_description: The electricity sector in New Zealand uses mainly renewable energy sources such as hydropower, geothermal power and increasingly wind energy. 82% of energy for electricity generation is from renewable sources, making New Zealand one of the lowest carbon dioxide emitting countries in terms of electricity generation. Electricity demand has grown by an average of 2.1% per year from 1974 to 2010 but decreased by 1.2% from 2010 to 2013.
  Regulation of the electricity market is the responsibility of the Electricity Authority. Electricity lines businesses, including Transpower and the distribution lines companies, are regulated by the Commerce Commission. Control is also exerted by the minister of energy in the New Zealand Cabinet, though the minister for state-owned enterprises and the minister for climate change also have some powers by virtue of their positions and policy influence in the government.
context_section_description: The HVDC Inter-Island scheme is New Zealand's only high voltage direct current (HVDC) system, and links the North and South Island grids together.
  The link connects the South Island converter station at the Benmore Dam in southern Canterbury with the North Island converter station at Haywards substation in the Hutt Valley via a 610 km long overhead bipolar HVDC line with submarine cables across Cook Strait.
  The HVDC link was commissioned in 1965 as a ±250 kV, 600 MW bipolar HVDC scheme using mercury-arc valve converters, and was originally designed to transfer surplus South Island hydroelectric power northwards to the more populous North Island. In 1976, the control system of the original scheme was modified to allow power to be sent in the reverse direction, from Haywards to Benmore.
  The HVDC link provides North Island consumers with access to the South Island's large hydro generation capacity, which may be important for the North Island during peak winter periods. For South Island consumers, the HVDC link provides access to the North Island's thermal generation capacity, which is important for the South Island during dry periods. Without the HVDC link, more generation would be needed in both the North and South Islands. In addition, the HVDC link is essential for the electricity market, as it allows generators in the North and South Islands to compete, putting downward pressure on prices and minimising the need to invest in costly new generating stations. The HVDC link also plays an important part in allowing renewable energy sources to be managed between the two islands.
  In 1992, the original mercury-arc equipment was paralleled to create a single pole (Pole 1), and a new thyristor-based pole (Pole 2) was commissioned alongside it. The transmission lines and submarine cables were also upgraded to double the link's maximum capacity to 1240 MW. The mercury-arc valve converter equipment was partially decommissioned in 2007, and fully decommissioned in August 2012. New thyristor converter stations (known as Pole 3) were commissioned on 30 May 2013 to replace the mercury arc converters. Further work to Pole 2 brought the link's capacity to 1200 MW by the end of the year.
caption: Haywards Pole 2 thyristor valve during maintenance shutdown
exif: {}