Western Interconnection

Western Interconnection
Name	Western Interconnection
Type	Electrical grid interconnection
Area	Western North America
Established	20th century
Operators	Numerous transmission operators and balancing authorities

Western Interconnection

The Western Interconnection is a wide-area alternating current electrical grid covering much of western North America. It links large portions of the United States, Canada, and parts of Mexico through high-voltage transmission networks managed by multiple transmission operators, balancing authorities, and regulatory bodies. The system underpins power delivery for major population centers, industrial regions, and renewable energy zones while interfacing with other grids via high-voltage direct current links.

Overview

The Western Interconnection connects large-scale infrastructure entities such as Bonneville Power Administration, California Independent System Operator, Electric Reliability Council of Texas, North American Electric Reliability Corporation, Federal Energy Regulatory Commission, and Public Utility Commission of Texas with regional players like British Columbia Hydro and Power Authority, Hydro-Québec in planning dialogues, and Arizona Public Service operators. It encompasses generation resources including Grand Coulee Dam, Glen Canyon Dam, Hoover Dam, Banqiao Dam-style hydro precedents, and thermal plants like Palo Verde Nuclear Generating Station and San Onofre Nuclear Generating Station (retired), while integrating renewable projects such as Alta Wind Energy Center, Ivanpah Solar Power Facility, and Garrad Hassan-designed farms. Grid planning involves institutions like North American Electric Reliability Corporation, Western Electricity Coordinating Council, California Energy Commission, U.S. Department of Energy, and Natural Resources Canada.

History and Development

Early development drew on interregional projects led by entities such as Bonneville Power Administration, Pacific Gas and Electric Company, Southern California Edison, and Los Angeles Department of Water and Power, with foundational transmission corridors influenced by policies from Tennessee Valley Authority-era initiatives and Warren G. Harding-era infrastructure debates. Postwar expansion accelerated with projects connected to Grand Coulee Dam and wartime industrialization near Los Angeles, San Francisco, and Seattle. The emergence of independent system operators like California Independent System Operator and market reforms influenced by Federal Energy Regulatory Commission orders reshaped operations alongside reliability standards developed by North American Electric Reliability Corporation and regional oversight by Western Electricity Coordinating Council. Cross-border coordination involved agreements between United States Department of Energy and Natural Resources Canada, and later consultations with Comisión Federal de Electricidad in Mexico.

Geography and Coverage

The interconnection spans diverse geographies from coastal corridors near Los Angeles and San Francisco to inland basins like the Great Basin, mountain regions including the Rocky Mountains and Sierra Nevada, and northern reaches into British Columbia and Alberta. It serves metropolitan regions such as Seattle, Portland, Oregon, Las Vegas, Phoenix, Arizona, Denver, and Calgary while reaching industrial centers like Salt Lake City and San Diego. Transmission corridors cross international borders at crossings near Blaine, Washington, Peace Arch Border Crossing, and links to Tijuana zones, with coastal interconnection prospects tied to ports like Los Angeles Port and Long Beach. The network intersects diverse climatic zones from Sonoran Desert to Pacific Northwest temperate rainforests.

Electrical Grid Structure and Operation

The system operates at multiple voltage levels using high-voltage AC transmission, subtransmission, and distribution components managed by entities including Transmission System Operators, Balancing Authorities, and utilities like Pacific Gas and Electric Company, Salt River Project, and Avista. Synchronous operation across the interconnection requires coordination of frequency and phase with reference to standards by North American Electric Reliability Corporation and contingency protocols influenced by historical disturbances such as the Northeast Blackout of 1965 and Southwest blackout-era studies. Control centers employ technologies from suppliers like Siemens, General Electric, and Schneider Electric and coordinate reserve margins, load forecasting, and dispatch across markets administered by California Independent System Operator and balancing areas in British Columbia Hydro and Power Authority territory. Integration of variable renewables necessitates grid-scale storage deployments including projects resembling Pumped-storage hydroelectricity sites and battery installations modeled after Hornsdale Power Reserve concepts.

Major Utilities and Operators

Prominent utilities and operators within the interconnection include Pacific Gas and Electric Company, Southern California Edison, Los Angeles Department of Water and Power, Bonneville Power Administration, BC Hydro, Salt River Project, Arizona Public Service, Nevada Power Company, Portland General Electric, Edison International, Xcel Energy, and municipal systems like Seattle City Light. System operators and coordinating organizations include California Independent System Operator, Western Electricity Coordinating Council, North American Electric Reliability Corporation, Federal Energy Regulatory Commission, and regional transmission organizations with ties to Independent System Operator New England for comparative policy exchange.

Interties and Connectivity

Cross-border and interconnection links include high-voltage direct current and AC ties such as the Pacific DC Intertie, Path 15, Intermountain Power Project, Bobcat Ridge-style corridors, and proposed expansions like the TransWest Express Transmission Project and SunZia. Interties connect to the Eastern Interconnection via limited DC links, and to Mexico grids via links coordinated with Comisión Federal de Electricidad. Major north–south and east–west corridors include Path 66, Path 46, and Path 27 designations used in planning documents by Western Electricity Coordinating Council and transmission planners.

Reliability, Regulation, and Market Dynamics

Reliability regimes are governed by standards from North American Electric Reliability Corporation and regional enforcement by entities like Western Electricity Coordinating Council and oversight by Federal Energy Regulatory Commission and provincial regulators including British Columbia Utilities Commission and California Public Utilities Commission. Market dynamics are shaped by electricity markets administered by California Independent System Operator, bilateral contracting involving Pacific Gas and Electric Company and Southern California Edison, state policies from California Energy Commission and Arizona Corporation Commission, and federal initiatives by U.S. Department of Energy. Resource adequacy, renewable portfolio standards influenced by California Global Warming Solutions Act of 2006, and transmission planning under statutes such as Federal Power Act drive investment, while operational resilience considers extreme events studied in reports by National Renewable Energy Laboratory and Lawrence Berkeley National Laboratory.

Category:Electric power transmission in North America