The system was operating in 1970, until an earthquake devastated the Sylmar converter station, near Los Angeles. Operation was restored by 1973. A few years later, the owners raised the transmission rating to 2,000 A and 1,600 MW, the equipment's inherent capacity.
Pacific Intertie upgrade
Increasing power demand as older generation around Los Angeles was retired led operators to upgrade capacity on the Pacific Intertie transmission by raising line voltage resulting in a total capacity of 2,000 MW. The Pacific Intertie upgrade (PIU) was commissioned by Hitachi Energy in 1985.
Pacific Intertie expansion
In 1985, Hitachi Energy was contracted to extend the Pacific Intertie transmission to 3,100 MW - the Pacific Intertie expansion (PIE). New 1,100 MW converter stations were installed in parallel with existing stations, and current in the DC line rose to 3,100 A. The PIE was commissioned in 1989.
Sylmar converter station
Damaged in a 1994 earthquake, the Sylmar converter station's original mercury-arc valves were also nearing the end of their design life, so the owners LADWP built a new 500 kV, 3,100 MW converter station at the existing facility. The existing converters and control building were modified, and the valve halls and as much existing equipment as possible reused. The new station went into service in 2004.
Celilo station upgrade
In 2013, to secure the reliability of this major power supply, Bonneville Power Administration, the owners of the Celilo northern station, decided to make a refurbish and upgrade station capacity to 3,800 MW. Hitachi Energy commissioned the upgraded station in 2016.
Sylmar station upgrade
In 2017, owners of the southern station LADWP decided to upgrade the AC and DC filers, shunt reactors, measurement and auxiliary equipment and an upgrade to the latest version of the digital MACH control and protection system in the Sylmar southern station. The Celilo station was the first station in the world to benefit from the latest generation of MACH and this upgrade in Sylmar will complete the modernization of the link, providing an exceptional level of control and helping to secure power supplies.
|Commissioning year:||2020, 2016, 2004, 1989, 1985, 1970|
|Power rating:||1,440 -> 1,600 -> 2,000 -> 3,100 -> 3,800 MW (Celilo) / 3,220 MW (Sylmar)|
|No. of poles:||2|
|AC voltage:||230 kV (Sylmar), 500/230 kV (Celilo)|
|DC voltage:||± 400 kV -> ± 500 -> ± 560 kV (Celilo)|
|Length of overhead DC line:||1,360 km|
|Main reason for choosing HVDC:||long distance, network stability|
|Application:||1970 connecting remote generation;
1989 connecting remote generation;
2004 upgrade (Sylmar);
2016 upgrade (Celilo);
2020 upgrade (Sylmar)