HVDC Vancouver Island

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The HVDC Vancouver Island is the name for HVDC interconnection between the Vancouver Island Terminal (VIT) near North Cowichan, British Columbia on Vancouver Island at 48°49′39″N 123°42′55″W / 48.82750°N 123.71528°W / 48.82750; -123.71528 (Vancouver Island Terminal ( North Cowichan Static Inverter Plant)) and the Arnott Substation (ARN) near Delta, British Columbia at 49°5′31″N 123°2′31″W / 49.09194°N 123.04194°W / 49.09194; -123.04194 (Arnott Substation ( Delta Static Inverter Plant)) on the Canadian mainland, which went into operation in 1968 and was extended in 1977. HVDC Vancouver Island consists of three overhead line sections with a total length of 42 kilometres and two submarine cable sections with a length of 33 kilometres.

After its departure of Arnott Substation the overhead power line on the mainland split at 49°3′38″N 123°4′30″W / 49.06056°N 123.07500°W / 49.06056; -123.07500 (Powerline Branch) into two branches, one running to a terminal at 49°3′6″N 123°7′22″W / 49.05167°N 123.12278°W / 49.05167; -123.12278 (Mainland Cable Terminal 1) and the other running to a terminal at 49°1′40″N 123°6′1″W / 49.02778°N 123.10028°W / 49.02778; -123.10028 (Mainland Cable Terminal 2), where the first submarine cable section begins. At 48°55′07″N 123°24′15″W / 48.91861°N 123.40417°W / 48.91861; -123.40417 (Galiano Island Cable Terminal East), the first submarine cable sections ends and a short overhead line section running southwestly across Galiano Island starts. The overhead line leaves Galiano Island south of Montague Harbour in an 880 metres long span, which starts at 48°52′51″N 123°23′21″W / 48.88083°N 123.38917°W / 48.88083; -123.38917 (Galiano Island-Parker Island Span East End) and ends on Parker Island at 48°52′48″N 123°24′04″W / 48.88000°N 123.40111°W / 48.88000; -123.40111 (Galiano Island-Parker Island Span West End). A bit westward on Parker Island at 48°52′45″N 123°24′9″W / 48.87917°N 123.40250°W / 48.87917; -123.40250 (Parker Island Cable Terminal) the overhead line ends and the second submarine cable section begins. At 48°51′2″N 123°25′31″W / 48.85056°N 123.42528°W / 48.85056; -123.42528 (Salt Spring Island Cable Terminal) the cable reaches Salt Spring Island and the third overhead line section starts. It crosses Salt Spring Island westsouthwestly. North of Maxwell Point at 48°49′54″N 123°33′50″W / 48.83167°N 123.56389°W / 48.83167; -123.56389 (Sansum Narrows DC Powerline Span East End) and Arbutus Point at 48°49′40″N 123°35′21″W / 48.82778°N 123.58917°W / 48.82778; -123.58917 (Sansum Narrows DC Powerline Span West End) the overhead line crosses in a 1900 metres long span of Sansum Narrows, the strait between Salt Spring Island and Vancouver Island. After this span the overhead line runs westward to Vancouver Island Terminal near the town of Duncan.

In 1968 the first pole of the HVDC Vancouver Island link went into service. Its static inverters use mercury vapour rectifiers. The maximum transmission capacity of this pole is 312 megawatts and the transmission voltage is 260 kV. The stations Vancouver Island Terminal and Arnott Substation were designed and delivered by Swedish company ASEA (later ABB). The Swedish team of some 10 people were headed for the first phase by Ivan Hedlund and for the second phase by Gunnar Ahgren.

In 1977 the HVDC Vancouver Island link was supplemented by installing a second pole. This pole uses thyristor valves for its static inverters and operates at a voltage of 280 kV with a rating of 370 megawatts. A new 230 kV. submarine cable for three-phase alternating current has been constructed between the Canadian mainland and Vancouver Island, that parallels the existing two HVDC lines and replaces one of two earlier 138kV lines. The HVDC systems are at the end of their service life and are not considered to be reliable.

Electrodes and Metallic Return[edit]

HVDC Vancouver Island uses during monopolar operation metallic return when current is lower than 600 A, otherwise earth return. On Vancouver Island the line for metallic return is a monopolar line on wooden poles, which are used in some sections also by AC lines, running parallel to the main line of HVDC Vancouver Island. On the mainland, it uses until a point at 49°3′39″N 123°2′34″W / 49.06083°N 123.04278°W / 49.06083; -123.04278 (Metallic Return Branch) the poles of the electrode line, after this point it runs on wooden poles together with a single-circuit three-phase AC line until 49°2′25″N 123°4′32″W / 49.04028°N 123.07556°W / 49.04028; -123.07556 (Metallic Return Cable Terminal). From there it runs as underground cable to Splasdown Park, where it transits at 49°1′58″N 123°5′26″W / 49.03278°N 123.09056°W / 49.03278; -123.09056 (Metallic Return Cable Terminal) again into an overhead line, which ends at the terminal of the main line at 49°1′40″N 123°6′1″W / 49.02778°N 123.10028°W / 49.02778; -123.10028 (Mainland Cable Terminal 2).

The electrode on the Canadian Mainland is a land electrode situated at Boundary Bay at 49°03′25″N 123°01′46″W / 49.05694°N 123.02944°W / 49.05694; -123.02944 (Boundary Bay Ground Electrode). It is connected with Arnott Substation by an overhead pole line with 2 conductors. The electrode on Vancouver Island is a shore electrode in a bay at Sansum Narrows at 48°46′22″N 123°34′24″W / 48.77278°N 123.57333°W / 48.77278; -123.57333 (Sansum Narrows Ground Electrode). It is connected with Vancouver Island Terminal by an overhead line with 2 conductors, which is installed on wooden poles. It runs between Vancouver Island Terminal and a point northwest of Maple Bay at 48°49′35″N 123°37′38″W / 48.82639°N 123.62722°W / 48.82639; -123.62722 (Sansum Narrows Ground Electrode Line Branch) parallel to other powerlines.

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