One major advantage of High-voltage direct current over AC is that the DC current penetrates the entire conductor as opposed to AC current which only penetrates the so-called skin depth, which is inversely proportional to the square root of the frequency. Even for a frequency as low as 60 Hz the skin depth is less than the 1.6″ radius of the conductor used for the Intertie. Hence the effective resistance is greater with AC than DC, so that more power is lost to heat. A DC line is also ideal for connecting together two AC systems that are not synchronized with each other. Also, cascading blackouts are less likely.
The Pacific Intertie takes advantage of differing power demand patterns between the northwestern and southwestern US. During winter, the northern region operates electrical heating devices while the southern portion uses relatively little electricity. In summer, the north uses little electricity while the south reaches peak demand due to air conditioning usage. Any time the Intertie demand lessens, the excess is distributed elsewhere on the western power grid (states west of the Great Plains, including Colorado and New Mexico).[2]’
The Pacific DC Intertie (also called Path 65) is an electric power transmission line that transmits electricity from the Pacific Northwest to the Los Angeles area using high voltage direct current (HVDC). The line capacity is 3,100 megawatts, which is enough to serve two to three million Los Angeles households and is 48.7% of the Los Angeles Department of Water and Power (LADWP) electrical system’s peak capacity.[1]
