ideal for connecting two AC systems that are not synchronized with each other. HVDC lines can help stabilize a power grid against cascading blackouts since power flow through the line is controllable. 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). Components The Pacific Intertie consists of: The Celilo Converter Station which converts three phase 60 Hz AC at 230 to 500 kV to ±500 kV DC (1000 kV pole-to-pole) at . The grounding system at Celilo consists of 1,067 cast iron anodes buried in a trench of petroleum coke, which behaves as an electrode, arranged in a ring of circumference at Rice Flats (near Rice, Oregon), which is SSE of Celilo. It is connected to the converter station by two aerial ACSR (aluminum conductor, steel reinforced) conductors, which end at a "dead-end" tower situated at . A overhead transmission line consisting of two steel-cored ACSR conductors, each in diameter with a conducting cross-sectional area of , carrying 500 kV. The two lines when combined have a capacity of 3.1 gigawatts (in bipolar mode). The Sylmar Converter Station () which converts DC to 230 kV AC (a process also called inverting) and is phase-synchronized with the L.A. power grid. The Sylmar grounding system is a line of 24 silicon-iron alloy electrodes submerged in the Pacific Ocean at Will Rogers State Beach suspended in concrete enclosures about above the ocean floor. The grounding array, which is from the converter station and is connected by a pair of ACSR conductors, which are in the sections north of Kenter Canyon Terminal Tower at installed instead of the ground conductors on the pylons. It runs from Kenter Canyon Terminal Tower, via DWP Receiving Station U (Tarzana; a former switching station), Receiving Station J (Northridge) and Rinaldi Receiving Station (also a former switching station) to Sylmar Converter Station. On the section between Receiving Stations J and Rinaldi, one of the two shielding conductors on each of two parallel-running 230 kV transmission lines is used as electrode