HVDC Technology

Understanding DC Transmission

Direct current (DC) is the preferred technology for moving large amounts of power across long distances. DC results in overall higher efficiency and reliability than an equivalently-sized alternating current (AC) system moving the same amount of power.

The Advantages of DC

More efficient: Over long distances, DC transmission can move more power with less electrical losses than an equivalent AC transmission line.

Lower Cost: Higher efficiency means a lower transmission cost, helping renewable energy compete against other power sources.

Improved Reliability: DC transmission can enhance system stability, allow the operator complete control over power flow, and facilitate the integration of wind from different resource areas.

Direct Current (DC):
The flow of electric charge in only one direction
Alternating Current (AC):
The movement of electric charge that periodically reverses direction

Smaller Footprint: DC transmission lines require narrower right-of-way footprints, using less land, than equivalent AC lines.

The major advantage of DC power lines is their efficiency—less energy is lost as it is transmitted and there is no need for reactive compensation along the line. Because DC flows steadily through the wires without changing direction many times each second and through the entire conductor rather than at the surface, DC transmission lines typically lose less power than AC transmission lines.