White Papers

Celilo HVdc Terminal Upgrade Project – Pacific NW-SW HVdc Intertie System

By Mark A. Reynolds P.E. and Brian C. Furumasu P.E.


The Pacific NW-SW HVdc Intertie System (PDCI) was the first major HVdc link in the US. Originally commissioned in 1970, the 845-mile (1,360-kilometer) PDCI transmits electricity between the Pacific Northwest and Southern California. The original transmission line designers very prudently built in the extra line ampacity to allow the various upgrades to be done.

This paper, presented at CIGRE 2016, provides an overview of the project to complete the upgrade of the Northern HVdc Terminal of the Pacific DC Intertie (PDCI). It is of interest to owners of other HVdc links which are approaching end of life. Conservative transmission line design enabled the link capacity to be increased ultimately by elevating the DC voltage to ± 560 kV and the current to 3410 Amperes and an ultimate power level (sending end) of 3800 MW. The commercial value of the transmission path allowed unique approaches to the replacement of virtually all the main circuit equipment in this significant undertaking. Partial results of performance testing are provided, along with a summary of the various challenges during the overall project.

Click here to request a copy of this paper.