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Technological DNA: HVDC Advancement

Aug. 24, 2023
The 40-year-old Châteauguay HVDC back-to-back converter station refurbishment represents more than an upgrade; it’s transformational in its scope.

I don’t know how many times I have heard the term “next generation” applied to some technological advancement. It’s a handy phrase to describe the latest innovation of a specific improvement of a digital technology. It’s also used to emphasize something that is modern, up to date, or the next big thing. It’s easy, however, to get mixed up or lost. This is especially true if there have been so many developments people are at a loss how to characterize them. Maybe it might help to use something like a family tree or DNA. It would give an indication of how yesterday and today’s technologies are related yet different.

What got me thinking about this was a discussion I had last month with Andreas Berthou, global head of HVDC (high-voltage direct current) at Hitachi Energy. We got together to discuss the application of HVDC technology on the SunZia Transmission project. Editor’s note, see T&D World’s August “Charging Ahead” ( for the complete story. In the course of our discussion, Andreas mentioned that Hitachi Energy had been selected by Hydro-Québec to upgrade their 40-year old Châteauguay HVDC back-to-back converter station.

Châteauguay’s refurbishment represents more than an upgrade, it’s transformational in its scope. It caught my attention because I have had a long standing interest with Châteauguay that extends back to its pre-commissioning days. I really wanted to talk more about Châteauguay, but that wasn’t possible. SunZia was the focus of that article and space was limited, so we moved on.

Digging Deeper   

After finishing that assignment, I had some time to dig into the links Andreas had sent me and learn more about how Châteauguay was being rejuvenated. Early in my engineering career, I was the lead engineer on the Blackwater back-to-back HVDC converter station, which had a great deal in common with Châteauguay. The two converter stations were related by the same lineage of HVDC technology they shared. It’s important  to recognize they didn’t represent different generations, but were more like siblings sharing a technological DNA. This DNA stretched back to the early days of thyristor-based LCC-HVDC (line commutated converter) systems.

The idea that applications such as Châteauguay and Blackwater could share DNA is a valuable concept when it comes to assembling this family tree. After all in its simplest terms, DNA is the information passed from one generation to the next. Over the course of my career, I was able to visit all of the converter stations represented in that family tree except one. That was the Cahora Bassa converter station, which was the patriarch of the line, but of the ones I did visit, it was easy to see the differences and the similarities.

Each member of this family represented an important milestone that improved the overall advancement of HVDC technology. Valuable data was gathered from their successes as well as their failures. That is why Châteauguay’s renovation had my attention. The power grid is changing, and this facility is moving from LCC-HVDC technology into the state-of-the-art VSC (voltage source converter) technology.

Technological DNA 

So what’s this update all about? Châteauguay was commissioned in 1984 and providing clean renewable energy long before that was the cool thing to do. Hydro-Québec is one of the largest hydroelectricity producers in the world and their Châteauguay facility connects the electrical networks of Québec in eastern Canada with the state of New York using HVDC technology. HVDC was used since the two networks are asynchronous (i.e., out of phase) and cannot be connected directly using traditional AC (alternating current) systems.

Originally Châteauguay consisted of two separate 500 megawatt (MW) converter stations with a total rating of 1,000 MW, but that is changing. In late 2022 Hydro-Québec selected Hitachi Energy to refurbish Châteauguay with its VSC-HVDC technology. It increases the facility’s rating by 50 percent to 1,500 MWs. The VSC-HVDC upgrade interconnects the 735 kV (kilovolt) Canadian grid with the 765 kV New York grid, which will increase the efficiency and controllability of the Châteauguay facility.

Because of the robustness of the original HVDC DNA developed for this family of converters, it is possible to splice it with VSC-HVDC DNA. That opens new doors when utilities consider upgrading their power electronics. Châteauguay’s features will include black start capabilities, require no reactive power supplements, lower active power losses, and other improved traits commonplace in today’s HVDC schemes. It’s going to be interesting seeing how DNA splicing like this changes our ideas about updating technologies!

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