The Intermountain HVDC transmission

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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 1600 MW at ±500 kV DC, but the link has subsequently been upgraded to 1920 MW. Each pole has a 1200 MW continuous and 1600 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.

Main data
Commissioning year:	1986
Power rating:	1 920 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