Case Study

Operational Studies of HVDC Links into a Provincial Utility Network

Client locations:

Newfoundland Labrador
Services: HVDC + Facts
Client/Project Profile:

Early in 2000s the provincial utility began considering various options for replacing the conventional generation with hydro electricity. The most economic way of bringing power from remote generation to the load center was found to be HVDC transmission. 

Our first involvement with this project began in 2007, when we were hired to perform studies evaluating a three-terminal LCC HVDC system. Fast forward to today, we are proud to be working together with our client’s team as the HVDC projects come into service.


The utility’s power system is undergoing many new developments, including the installation of a 500 MW VSC HVDC link, a 900 MW LCC HVDC link, three new synchronous condensers, four new hydro generators as well as several new high voltage AC lines. 

TGS was asked to provide support to our client through the process of integrating the new equipment, as these are major changes that are taking place in their relatively small system. Their power system has always been an islanded power system, with no outside interconnections. Now, the two new HVDC systems connect the island to other grids, which significantly changes the way their power system will operate.


Most recently, TGS has been supporting our client by performing operational studies to determine the system operating limits for each of the stages of equipment coming into service. TGS has also performed numerous additional studies, as listed below:

PSSE – Operational Studies

  • Power flow – contingency analysis to determine system operating limits to meet thermal and steady-state voltage criteria
  • Transient stability – fault simulations to determine system operating limits to meet dynamic performance criteria
  • Determination of system’s under frequency load shedding (UFLS) scheme and spinning reserve requirements
  • Coordination of the two HVDC links – Frequency controllers and HVDC runbacks

PSCAD – Energization and switching studies

  • Various PSCAD (EMT) studies to investigate energization and switching of new equipment including transformers, reactors, breakers and AC lines

TGSSR – Tuning of all Power System Stabilizers (PSS) on the Island

  • Study to determine optimal PSS parameters for approximately 10 generating stations on the Island

RTDS – Model Development for Factory Acceptance Testing (FAT)

  • Starting from PSSE cases of the system, developed reduced equivalent AC network models for RTDS, for use in the FAT for the new HVDC link


Over the years we have applied our power system analysis expertise to study our client’s system, which has given us detailed knowledge and understanding of their system.

We are proud to have a long-standing relationship with this utility’s team, and look forward to working together long into the future on this and other interesting projects!