Path 26

Path 26 is an electrical transmission corridor in California linking southern and northern parts of the California Independent System Operator balancing area. It forms a critical north–south transmission capability enabling transfers between the Los Angeles Department of Water and Power, San Diego Gas & Electric, Southern California Edison regions and the Pacific Gas and Electric Company and Sacramento Municipal Utility District service areas. The corridor's thermal, stability and congestion characteristics have influenced planning at Federal Energy Regulatory Commission, California Energy Commission and regional planning groups such as the Western Electricity Coordinating Council.

Route description

Path 26 traverses high-voltage right-of-way across multiple counties and subregions. It includes segments of 500 kV and 230 kV transmission lines that pass through or near Los Angeles County, Kern County, Tulare County, Fresno County, Merced County, and Sacramento County. Major line segments parallel or interconnect with corridors serving substations like Whirlwind Substation, Vincent Substation, Buttonwillow Substation, Tesla Substation, and Miguel Substation. The routing negotiates varied terrain including the San Joaquin Valley, the southern Sierra foothills, and peri-urban areas adjacent to Bakersfield, Fresno, and Modesto. The corridor interfaces with other interties such as Path 15, Path 46, and local radial systems serving Irvine, Santa Barbara, and San Francisco Bay Area utilities.

History

Development of the corridor dates to expansion programs in the 1960s and 1970s driven by load growth in Los Angeles and resource shifts in northern California. Early projects involved utilities including Pacific Gas and Electric Company, Southern California Edison, and the Los Angeles Department of Water and Power coordinating with state planners such as the California Public Utilities Commission and federal regulators like the Federal Energy Regulatory Commission. During the 1980s and 1990s, major upgrades paralleled transmission initiatives associated with projects by California Department of Water Resources and generation additions from facilities sited by Duke Energy-affiliated projects and independent power producers such as Calpine and Dynegy. Post-2000 reliability events and market congestion prompted studies led by California Independent System Operator and regional organizations like the Western Electricity Coordinating Council and the North American Electric Reliability Corporation, producing reinforcements, dynamic ratings, and operational protocols. Notable modernization efforts involved coordination with environmental agencies including the California Department of Fish and Wildlife and California Air Resources Board to mitigate impacts.

Major junctions and interconnections

Path 26 links multiple high-capacity nodes and interties. Key interconnection points include the northern interface at Midway Substation and Round Mountain Substation near Sacramento, the central nodes at Buttonwillow Substation and Vernon Substation near Bakersfield and Los Angeles, and southern interfaces connecting to Miguel Substation and Pacoima Substation. It synchronizes with parallel corridors such as Path 15—the major north–south backbone—and meshes with the Pacific DC Intertie and alternating current interfaces tied to Hoover Dam-fed systems. Market and reliability hubs nearby include the Los Angeles Department of Water and Power control center, California Independent System Operator dispatch, and reserves interfacing with balancing areas managed by San Diego Gas & Electric and Sacramento Municipal Utility District. Ancillary equipment at junctions includes phase-shifting transformers and series compensation facilities installed in partnership with vendors like Siemens Energy and General Electric.

Operations and management

Operational control of the corridor is coordinated primarily by the California Independent System Operator with participation from tenant utilities including Southern California Edison, Pacific Gas and Electric Company, Los Angeles Department of Water and Power, and San Diego Gas & Electric. Management practices include dynamic line rating, real-time thermal monitoring, and contingency analysis following standards set by the North American Electric Reliability Corporation and enforced by the Federal Energy Regulatory Commission. Market mechanisms such as congestion pricing, locational marginal pricing developed by California Independent System Operator, and transmission rights administered under tariffs overseen by the California Public Utilities Commission and Federal Energy Regulatory Commission govern economic flows. Routine maintenance, vegetation management, and wildfire mitigation plans are coordinated with state agencies including California Department of Forestry and Fire Protection and regional emergency managers like California Office of Emergency Services.

Impact and significance

Path 26 affects reliability, resource access and wholesale markets across California and the western interconnection. Its capacity constrains have shaped generation siting decisions by companies such as Calpine, Nextera Energy, AES Corporation, and utility-scale Iberdrola USA affiliates, and influenced renewable integration strategies promoted by California Energy Commission and California Public Utilities Commission. Congestion on the corridor has driven transmission investment proposals by entities like Pacific Gas and Electric Company and Southern California Edison, and spurred policy responses from Federal Energy Regulatory Commission concerning return on equity and cost allocation. In extreme weather or contingency events, load relief and re-dispatch orchestrated via California Independent System Operator and mutual assistance from organizations such as the Western Electricity Coordinating Council rely on Path 26 capacity. The corridor thereby remains central to discussions of decarbonization, grid resilience, and multi-state resource sharing involving stakeholders like California Independent System Operator, California Energy Commission, Federal Energy Regulatory Commission, North American Electric Reliability Corporation, and major municipal utilities.

Category:Electric power transmission in California