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What a Transmission Line Design Engineer Needs to Know about HVDC

By Ronald Carrington, P.E., POWER Engineers


With the expansion of the transmission grid to accommodate renewable energy generated far from load centers, a number of High Voltage Direct Current (HVDC) lines are being proposed. Since the grid in North America is primarily comprised of highly interconnected Alternating Current (AC) transmission lines, a transmission line engineer/ designer rarely is exposed to HVDC facilities.

Although AC and DC transmission lines are greatly similar from a structural perspective, the fundamental electrical differences between AC and DC require the transmission design engineer to make a number of adjustments to a “normal” AC line design when designing an HVDC transmission line.

This paper will provide an overview and high level discussion of the topics, components and practices that must be considered in the design of an HVDC line that are different or require modification from conventional AC design practices. Subjects to be highlighted include design approach for HVDC, corona field effects, current return path and insulation design.

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