View source for Pacific DC Intertie

{{short description|HVDC power line in the United States}}
{{Infobox power transmission line
| name                = Pacific DC Intertie
| photo               = Powerlines, Washoe County, Nevada (3070983825).jpg
| caption             = Pacific DC Intertie guyed pylon, Washoe County, Nevada
| map                 = {{maplink |type=line |frame=yes |plain=yes |frame-align=center |zoom=3}}
| map_caption         = 
| country             = [[United States]]
| state               = 
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| coordinates         = 
| lat                 = 
| long                = 
| direction           = north–south
| start               = [[Celilo Converter Station]]
| through             = 
| finish              = [[Sylmar Converter Station]]
| par                 = 
| owner               = 
| partners            = 
| operator            = 
| cable_manufacturer  = 
| cable_installer     = 
| cable_layer         = 
| substation_manufacturer= 
| substation_installer= 
| contractors         = 
| construction        = 
| expected            = 
| est                 = 
| decom               = 
| type                = 
| current_type        = [[HVDC]] 
| length_km           = 
| capacity            = 
| AC_voltage          = 
| DC_voltage          = 
| poles_no            =
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}}
{{GeoGroup}}
[[File:Pacific intertie geographic map.png|thumb|right|Map of the route of the Pacific Intertie transmission route and stations|407x407px]]

The '''Pacific DC Intertie''' (also called '''Path 65''') is an [[electric power transmission]] line that transmits [[electricity]] from the [[Pacific Northwest]] to the [[Los Angeles]] area using [[HVDC|high voltage direct current]] (HVDC).  The line capacity is 3.1 [[gigawatts]], which is enough to serve two to three million Los Angeles households and represents almost half of the [[Los Angeles Department of Water and Power]] (LADWP) electrical system's peak capacity.<ref>{{cite web |author=Sharon Bernstein and Amanda Covarrubias |date=July 10, 2006 |title=Heat Wave Caught DWP Unprepared |url=https://www.latimes.com/archives/la-xpm-2006-jul-28-me-power28-story.html |work=[[Los Angeles Times]] |access-date=23 September 2020 }}</ref>

The intertie originates near the [[Columbia River]] at the [[Celilo Converter Station]] of [[Bonneville Power Administration]]'s grid outside [[The Dalles, Oregon]] and is connected to the [[Sylmar Converter Station]] north of [[Los Angeles]], which is owned by five utility companies and managed by [[LADWP]]. The Intertie can transmit power in either direction, but power flows mostly from north to south.

The section of the line in Oregon is owned and operated by Bonneville Power Administration, while the line in Nevada and California is owned and operated by Los Angeles Department of Water and Power.<ref>{{cite web |url=https://www.bpa.gov/efw/Analysis/NEPADocuments/Pages/PDCI_Upgrade.aspx |title=Pacific Direct Current Intertie (PDCI) Upgrade Project (DOE/EA-1937) Lake, Jefferson, Crook, Deschutes, and Wasco counties, Oregon |publisher=Bonneville Power Administration |access-date=2019-12-29}}</ref> The transition is at the Oregon–Nevada border, at {{coord|41.9964|-119.9623|type:landmark_region:US-OR|name=Pacific Intertie ownership boundary|format=dms}}.

This is one of two HVDC lines serving Los Angeles; the other is [[Path 27]].

== Overview ==
The idea of sending [[hydroelectric]] power to [[Southern California]] had been proposed as early as the 1930s, but was opposed and scrapped.  By 1961, US president [[John F. Kennedy]] authorized a large public works project, using new [[high voltage direct current]] technology from [[Sweden]].  The project was undertaken as a close collaboration between [[General Electric]] of the US and [[ASEA]] of Sweden.  Private California power companies had opposed the project but their technical objections were rebutted by [[Uno Lamm]] of ASEA at an [[IEEE]] meeting in New York in 1963.  When completed in 1970 the combined AC and DC transmission system was estimated to save consumers in Los Angeles approximately US$600,000 per day by use of cheaper electric power from [[List of dams in the Columbia River watershed|dams on the Columbia River]].

One advantage of direct current over AC is that DC current penetrates the entire conductor as opposed to AC current which only penetrates to the [[skin depth]]. For the same conductor size, the effective resistance is greater with AC than DC, hence more power is lost as heat with AC. In general, the total cost for HVDC is less than an AC line if the line length is over 500–600 kilometers, and with advances in conversion technology, this distance has been reduced considerably. A DC line is also ideal for connecting two AC systems that are not synchronized with each other. HVDC lines can help stabilize a power grid against cascading blackouts since power flow through the line is controllable.

The Pacific Intertie takes advantage of differing power demand patterns between the northwestern and southwestern US. During winter, the northern region operates electrical heating devices while the southern portion uses relatively little electricity. In summer, the north uses little electricity while the south reaches peak demand due to air conditioning usage. Any time the Intertie demand lessens, the excess is distributed elsewhere on the [[Western Interconnection|western power grid]] (states west of the Great Plains, including [[Colorado]] and [[New Mexico]]).<ref>{{cite web
 |url         = http://www.ewh.ieee.org/r7/toronto/events/oct0303/prabha.ppt
 |format      = [[PowerPoint]]
 |title       = Power System Security in the New Industry Environment: Challenges and Solutions
 |author      = Prabha Kundur, Powertech Labs Inc.
 |page        = 17
 |publisher   = [[IEEE]]
 |date        = October 3, 2003
 |access-date  = 2006-09-11
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20060822101832/http://ewh.ieee.org/r7/toronto/events/oct0303/prabha.ppt
 |archive-date = August 22, 2006
}}</ref><gallery>
File:Img0259HVDC 500kV wire.JPG|The [[HVDC]] [[electric power transmission|power line]] in [[Los Angeles]] (shorter tower carrying two wires on the right). The power line crosses [[Interstate 5 in California|Interstate 5]] near the interchange with [[Interstate 210 and State Route 210 (California)|Interstate 210]] in [[Sylmar, Los Angeles|Sylmar]].
File:Path 65 P0002014.jpg|The Pacific DC Intertie along a service road paralleling [[U.S. Route 395 in California|U.S. Highway 395]].  Many of the towers of the Intertie are of this simple, slender design
File:Path 65 P0002019.jpg|The slender tower's base tapers down to a single point that is bolted to a concrete anchor
File:Path 65 P0002020.jpg|The slender tower is supported laterally by four [[guy-wire]]s
File:PacificIntertie.jpg|The Pacific Intertie outside of Benton, California
File:Pacific DC Intertie Towers near Fernley, Nevada.jpg|Pacific DC Intertie towers (left side) near [[Fernley, Nevada]]. The first few towers are self-supported. The towers on the far side use [[guy-wire]]s.
</gallery>

==Components==

The Pacific Intertie consists of:<ref>{{cite web
  | url = http://www.transmission.bpa.gov/cigresc14/Compendium/PACIFIC.htm
  | title = The Pacific Intertie Scheme
  | publisher = [[Bonneville Power Administration]]
  | date = 2000-11-03
  | access-date = 2009-08-20
|archive-url = https://web.archive.org/web/20050426045806/http://www.transmission.bpa.gov/cigresc14/Compendium/PACIFIC.htm |archive-date = 2005-04-26}}</ref>
* The [[Celilo Converter Station]] which converts three phase 60&nbsp;Hz [[alternating current|AC]] at 230 to 500 [[kilovolt|kV]] to ±500 kV [[direct current|DC]] (1000 kV pole-to-pole) at {{coord|45|35|39|N|121|6|51|W|type:landmark_region:US-OR|display=inline,title|name=Celilo Converter Station - Pacific DC Intertie (north end)}}.
** The grounding system at Celilo consists of 1,067 cast iron anodes buried in a {{convert|2|ft|cm|-1|adj=on|spell=in}} trench of [[petroleum coke]], which behaves as an electrode, arranged in a ring of {{convert|3255|m|mi|1|order=flip}} circumference at Rice Flats (near [[Rice, Oregon]]), which is {{convert|10.6|km|mi|order=flip}} SSE of Celilo.  It is connected to the converter station by two aerial {{convert|644|mm2|in2|abbr=on}} [[ACSR]] (aluminum conductor, steel reinforced) conductors, which end at a "dead-end" tower situated at {{coord|45.497586|-121.064620|type:landmark_region:US-OR|name=End of electrode line|format=dms}}.
* A {{convert|1361|km|mi|adj=on|order=flip}} overhead transmission line consisting of two steel-cored ACSR conductors, each {{convert|1.6|in|cm}} in diameter with a conducting cross-sectional area of {{convert|1171|mm2|in2|abbr=on}}, carrying 500&nbsp;kV.
** The two lines when combined have a capacity of 3.1 [[gigawatt]]s (in bipolar mode).
* The [[Sylmar Converter Station]] ({{coord|34|18|42|N|118|28|53|W|type:landmark_region:US-CA|name=Sylmar Converter Station - Pacific DC Intertie (south end)}}) which converts DC to 230 kV AC (a process also called [[Inverter (electrical)|inverting]]) and is phase-synchronized with the L.A. power grid.
** The Sylmar grounding system is a line of 24 silicon-iron alloy electrodes submerged in the [[Pacific Ocean]] at [[Will Rogers State Beach]]<ref>{{cite web|url=https://placesjournal.org/article/the-infrastructural-city/|title=Review of The Infrastructural City, edited by Kazys Varnelis |publisher=Places Journal}}</ref> suspended in concrete enclosures about {{convert|0.5|to|1|m|ft|0|sp=us|order=flip}} above the ocean floor.  The grounding array, which is {{convert|48|km|mi|0|order=flip}} from the converter station and is connected by a pair of {{convert|644|mm2|in2|abbr=on}} ACSR conductors, which are in the sections north of Kenter Canyon Terminal Tower at {{coord|34|04|04.99|N|118|29|18.5|W|type:landmark|name=Southern California Edison Malibu Substation, Pacific DC Intertie - End of overhead electrode line}} installed instead of the ground conductors on the pylons. It runs from Kenter Canyon Terminal Tower, via DWP Receiving Station U (Tarzana; a former switching station), Receiving Station J (Northridge) and Rinaldi Receiving Station (also a former switching station) to [[Sylmar Converter Station]]. On the section between Receiving Stations J and Rinaldi, one of the two shielding conductors on each of two parallel-running 230 kV transmission lines is used as electrode line conductor.

==History==
[[File:Sylmar Converter Station.jpg|thumb|Sylmar East station, rededicated as the Sylmar Converter Station in 2005 following the upgrade to 3,100&nbsp;MW.]]

The first phase of the scheme, completed in May 1970, used only [[mercury-arc valve]]s in the [[HVDC converter|converter]]s.<ref>Compendium of HVDC schemes, [[International Council on Large Electric Systems|CIGRÉ]] [https://e-cigre.org/publication/003-compendium-of-hvdc-schemes-throughout-the-world Technical Brochure No. 003], 1987, pp57-62.</ref> The valves were series connected in three six-pulse valve bridges for each pole. The blocking [[voltage]] of the valves was 133&nbsp;kV with a maximum [[current (electricity)|current]] of 1,800 [[ampere]]s, for a transmission rating of 1,440&nbsp;MW with a symmetrical voltage of 400 kV with respect to earth.

Each converter station housed six mercury arc valves groups, consisting each of seven valves, for a total of 42 valves in each converter.
The valves had a width of {{convert|2.15|m|ft|order=flip}}, a height of {{convert|3.2|m|ft|order=flip}} and a length of {{convert|3.5|m|ft|order=flip}} and weighed {{convert|14000|lb|kg}}. Each valve contained {{convert|1.1|litre|USfloz}} mercury, with a weight of {{convert|14.9|kg|lb|order=flip}}.

* 1972: After the [[Sylmar earthquake]], the [[Sylmar Converter Station]] had to be reconstructed due to extensive damage.
* 1982: The power rating of the mercury arc valve rectifiers was raised by various improvements to 1,600&nbsp;MW.
* 1984: The transmission voltage was pushed to 500&nbsp;kV and the transmission power was increased to 2,000&nbsp;MW by adding one six-pulse [[thyristor valve]] group rated at 100&nbsp;kV to each pole.
* 1989: A further increase of the transmission power to 3,100&nbsp;MW took place by installing a 1,100&nbsp;MW parallel connected thyristor converter in Celilo and Sylmar.  This upgrade started in 1985 was called the ''Pacific Intertie Expansion''.<ref>{{cite web |title=Pacific Intertie |url=https://www.hitachienergy.com/us/en/about-us/customer-success-stories/pacific-intertie |publisher=Hitachi Energy |access-date=20 April 2024}}</ref> This expanded the converter station to two sites, Sylmar West (situated at {{coord|34|18|32|N|118|29|13|W|type:landmark_region:US-CA|name=Sylmar West Converter Station - Pacific DC Intertie (south end)}})<ref>{{cite web |title=Sylmar West HVDC station |url=https://library.e.abb.com/public/4f3509951d3997cac1257b0c00552de5/Sylmar%20West%20HVDC%20station.kmz |publisher=ABB |access-date=20 April 2024}}</ref> and Sylmar East (situated at {{coord|34|18|42|N|118|28|53|W|type:landmark_region:US-CA|name=Sylmar East Converter Station - Pacific DC Intertie (south end)}}).<ref name=ABB/>
* 1993: One pole of the Pacific Intertie Expansion converter station at Sylmar was completely destroyed by fire.<ref>"Fire aspects of HVDC thyristor valves and valve halls", [[International Council on Large Electric Systems|CIGRÉ]] ''[https://web.archive.org/web/20150923221152/http://www.e-cigre.org/bib/136.pdf Technical Brochure No. 136]'', February 1999.</ref> The converter was replaced in 1994–1995 by [[Siemens]].<ref>Christl, N., Faehnrich, W., Lips, P., Rasmussen, F., Sadek, K., "Thyristor Valve Replacement Of The Pacific Intertie Expansion Sylmar East 500 Kv HVDC Converter Station", [[Institution of Electrical Engineers|IEEE]] Sixth International Conference on AC and DC Power Transmission (Conf. Publ. No. 423), 1996.</ref>
* 1994: After the Northridge earthquake, the Sylmar Converter Station had to be reconstructed due to extensive damage.
* 2004: The Sylmar East station was upgraded from 1,100&nbsp;MW to 3,100&nbsp;MW. The controls and older converters, including the mercury arc valves, were completely replaced by a single pair of 3,100&nbsp;MW 12-pulse converters built by [[ABB]]. This allowed the Sylmar East station to handle the full capacity.<ref name="ABB">{{cite news |title=ABB Rededicates Sylmar Converter Station (Press Release) |url=http://www.abb.com/cawp/seitp202/A719AD829B2496D085256FD4006BF446.aspx |publisher=ABB |date=24 March 2005 |archive-url=https://web.archive.org/web/20090201125328/http://www.abb.com/cawp/seitp202/A719AD829B2496D085256FD4006BF446.aspx |archive-date=1 February 2009}}</ref>  In parallel with this project, the six-pulse mercury arc valves at the Celilo Converter Station were replaced with [[Siemens]] [[light-triggered thyristor]]s in compliance with their [[Modified Age Replacement Policy]] (MARP).
* 2005: The Sylmar East station was rededicated as the Sylmar Converter Station.<ref name=ABB/>
* 2014-2015: The Celilo converter substation was upgraded in a similar manner to the Sylmar East upgrade.  The North converter was upgraded from 1,100&nbsp;MW to 3,100&nbsp;MW. The new converter was built by the [[ABB]].  The new converter connects at 500kV AC instead of the previous 230kV AC connection.  After completion, all of the equipment for the south converter was removed.<ref>"Celilo Converter Station", [[Bonneville Power Administration]] ''[https://www.bpa.gov/news/pubs/FactSheets/fs-201604-Celilo-Converter-Station.pdf]'', April 2016. (Fact Sheet)</ref><ref>"ABB completes upgrade of first major HVDC link in U.S. transmission history", [[ABB]] ''[https://new.abb.com/news/detail/45972/abb-completes-upgrade-of-first-major-hvdc-link-in-us-transmission-history]'' 20 June 2016. (press release)</ref>

==See also==
* [[Uno Lamm]]
* [[Path 27]]
* [[North American Electric Reliability Corporation]]
* [[WECC Intertie Paths]]
* [[Path 66]]

==References==
{{Reflist}}

==External links==
* [http://new.abb.com/systems/hvdc/references/pacific-intertie Pacific Intertie (abb.com) ]
* [https://web.archive.org/web/20050426045806/http://www.transmission.bpa.gov/cigresc14/Compendium/PACIFIC.htm The Pacific Intertie Scheme (BPA, via web.archive.com)]
* [http://wecc.biz/ Wecc.biz]

{{Power Transmission Corridors of the Western United States}}

{{DEFAULTSORT:Pacific Dc Intertie}}
[[Category:Energy infrastructure completed in 1970]]
[[Category:1970 establishments in California]]
[[Category:Energy infrastructure in Oregon]]
[[Category:Energy infrastructure in California]]
[[Category:HVDC transmission lines]]
[[Category:Western Interconnection]]