The Intermountain HVDC transmission

The second HVDC transmission to Los Angeles.

The Intermountain HVDC transmission system operated by the Los Angeles Department of Water and Power (LADWP) brings power from a coal-fired station in Utah to the Los Angeles area. The original rated power was 1 600 MW at ±500 kV DC. Subsequently the link has been upgraded to 1 920 MW, and an additional upgrade to 2 400 MW has now been implemented. Each pole has a 1 200 MW continuous and 1 600 MW short term overload capacity, to minimize the impact on the power system in the event of a pole outage.

Bird's eye view of Adelanto

Valve hall in Adelanto

The receiving station in Adelanto is located in a seismically active area. Suspended thyristor valves are therefore used to achieve maximum security. Extremely stringent requirements were imposed on reliability. ABB’s redundant converter control system was developed to meet these performance requirements. It has become ABB’s standard for HVDC in every project since Intermountain.

ABB had complete turnkey responsibility for the converter stations, which were commissioned in April 1986.

In 2010, ABB made an additional upgrade, which includes delivery of the MACH2 control system, additional AC filters and cooling system in order for the link to reach a transmission capacity of 2 400 MW.

Main data
Commissioning year:	1986, 2010
Power rating:	1 920 MW => 2 400 MW
No. of poles:	2
AC voltage:	345 kV (Intermountain), 500 kV (Adelanto)
DC voltage:	±500 kV
Length of overhead DC line:	785 km
Main reason for choosing HVDC:	Long distance