Project: Pacific Intertie HVDC Uprating

Service: LCC HVDC

Client: Bonneville Power Administration (BPA)

Country: USA

Year: 2012 — on-going support


The Pacific Direct Current Intertie (PDCI) is a 2-terminal LCC HVDC link in the USA. It is currently undergoing an upgrade to increase its rating to 3800 MW +/-560 kV. The project involves the replacement of the HVDC converters and associated equipment at the Celilo (northern) end of the HVDC link. TGS performed the pre-specification studies and wrote the technical specification for the HVDC converters. TGS is currently providing on-going support for the design review and factory acceptance testing, and will soon provide on-site commissioning support.

TGS Study services:

  • AC Network Reduction— performed using PSS/E
  • Custom PSCAD HVDC Model & Reduced AC System Model Development
  • System Impact Studies — performed using PSS/E
  • Power flow
  • Short circuit
  • AC voltage stability
  • Transient stability
  • Electromagnetic Transient Studies — performed using PSCAD
  • Harmonic Impedance Scans — at the HVDC terminal
  • AC Filter Performance Review — performed using TGS’ in house filter design software

TGS Owner’s Engineer services:

  • Development of the Technical Specification
  • Bid Evaluation
  • Review of HVDC manufacturer design reports
  • Witnessing factory performance and type testing
  • Commissioning


The Pacific Intertie HVDC Uprating project was unique in two major ways; The Celilo terminal will be refurbished and upgraded to allow future power transfers to a new link rating of 3,800MW while utilizing the existing Converter building at Celilo. Secondly, the southern terminal (Sylmar) will not be upgraded at the same time so the new system at Celilo has to be able to work with the existing system at Sylmar.