Western Interconnection

All of the electric utilities in the Western Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency of 60 Hz. The Western Interconnection stretches from Western Canada south to Baja California in Mexico, reaching eastward over the Rockies to the Great Plains.

Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties) such as the north-south Pacific DC Intertie, or with variable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. There are six DC ties to the Eastern Interconnection in the US and one in Canada, and there are proposals to add four additional ties. It is not tied to the Alaska Interconnection.

Consumption

In 2015, WECC had an energy consumption of 883 TWh, roughly equally distributed between industrial, commercial and residential consumption. There was a summer peak demand of 150,700 MW and a winter peak demand (2014–15) of 126,200 MW.