In this Blog, we discuss the amazing story of how a lowly 2,000 MW HVDC line was able to support a transmission capacity increase of 3,200 MW. 

“Will a 2,000 MW HVDC line transfer 2,000 MW?”

The answer, which we’ll try to explain in this blog, is “plus or minus” if the DC line is being built to overlay an existing AC system. In such a situation, the DC line may continually carry 2,000 MW but the incremental transfer will not necessarily equal 2,000 MW.

One of the ideas proposed for developing a transmission super highway is to construct a number of DC lines to overlay the existing AC system. The motivation comes from DC’s inherent capability to overcome voltage and stability issues for transfers over long distances, making the network electrically “smaller.” (There is also an economic motivation that is important to recognize, but which we will not treat in this article.) How would such a massive development change the nature of a power system? What issues do system planners have to consider? In a more global view, what would investors and regulatory agencies need to take into account in funding and approving this type of project?