Case Study

HVDC Upgrade Project

Client locations:

Services: HVDC + Facts
Client/Project Profile:

TGS was contracted to provide Owner’s Engineer services for an HVDC Upgrade project in the USA.

TGS personnel have a long history of HVDC project experience and are experts in designing, managing and delivering major infrastructure projects. Our experience is complemented with proficient global knowledge in the fields of study, specification, evaluation, contract negotiation, award, technical review, procurement, witnessing factory tests, and commissioning of major HVDC projects. Additionally, our team has decades of collective practical field experience in operation and maintenance of HVDC systems.

TGS’s involvement with this project began back in 2011, when the utility began to implement their HVDC upgrade project, as described below and ended in 2016 when the project was commissioned.


The HVDC project is an LCC HVDC link in the USA. The utility was planning to upgrade one terminal of the HVDC link to increase its rating to allow for higher power transfer. The project involved the replacement of the HVDC converters and associated equipment at the end of the HVDC link.

This HVDC Upgrade project was unique in two ways:

  • The HVDC terminal was refurbished and upgraded to allow future power transfers at a higher rating while utilizing the existing converter building. 
  • The terminal at the other end of the HVDC link was not upgraded at the same time so the new system at the upgraded terminal had to be able to work with the existing system at the other terminal.


TGS provided Owner’s Engineer services from the early days of pre-specification studies through to on-site commissioning, as listed below:

  • AC Network Reduction
  • Custom PSCAD HVDC Model & Reduced AC System Model Development
  • System Impact Studies 
  • Power flow
  • Short circuit
  • AC voltage stability
  • Transient stability 
  • Electromagnetic Transient Studies 
  • Harmonic Impedance Scans 
  • AC Filter Performance Review
  • Development of the Technical Specification
  • Bid Evaluation
  • Review of HVDC manufacturer design reports
  • Witnessing factory performance and type testing
  • Commissioning


TGS engineers worked together seamlessly with the utility’s team for approximately 5 years as the various stages of the project were executed, resulting in a successfully implemented project and great relationships built!

Since this project was successfully put into service, our client has provided excellent references for TGS on many Owner’s Engineer proposals.