Electric power transmission

Electric power transmission
Name	Electric power transmission
Caption	High-voltage transmission lines and towers
Type	Infrastructure
Introduced	1880s
Area	Energy sector
Related	Thomas Edison, Nikola Tesla, Westinghouse Electric, General Electric, Ames Hydroelectric Plant

Electric power transmission is the bulk transfer of electrical energy from generating facilities to distribution networks and large consumers via high-voltage lines, substations, and interconnects. It links large-scale generators such as Hoover Dam, Three Gorges Dam, and thermal plants operated by entities like Électricité de France and Tennessee Valley Authority to regional grids and major industrial users. Modern transmission systems are overseen by organizations including North American Electric Reliability Corporation, ENTSO-E, and national regulators like the Federal Energy Regulatory Commission.

History

Early demonstrations of alternating current and long-distance transmission involved inventors and firms such as Nikola Tesla, George Westinghouse, Thomas Edison, Westinghouse Electric, and General Electric. The development of high-voltage AC systems was catalyzed by projects like the Ames Hydroelectric Plant and the 1891 International Electrotechnical Exhibition in Frankfurt where three-phase systems were displayed. Interconnections expanded through the 20th century with national projects exemplified by Bonneville Power Administration, the Tennessee Valley Authority, and Soviet-era transmission linked to Dnieper Hydroelectric Station. Post-war growth saw the formation of regional operators such as PJM Interconnection and cross-border coordination via ENTSO-E.

Infrastructure and Components

A transmission network comprises high-voltage overhead lines, underground cables, substations, transformers, circuit breakers, and protection equipment. Key components are manufactured and supplied by firms like ABB, Siemens, Mitsubishi Electric, and Schneider Electric. Major transmission corridors traverse terrain managed by agencies including U.S. Bureau of Land Management and cross borders under treaties involving entities such as the European Union and bilateral agreements between nations like Canada and the United States. Right-of-way and tower siting interact with jurisdictions of states such as California and provinces like Ontario.

Transmission System Operation

System operators coordinate generation, load balancing, and contingency management through control centers run by organizations including California Independent System Operator, ISO New England, and National Grid (UK). Market mechanisms for transmission access and congestion management are administered under rules from Federal Energy Regulatory Commission and regional transmission organizations such as Midcontinent Independent System Operator. Scheduling, dispatch, and ancillary services rely on telemetry, SCADA, and energy management systems developed by vendors like Schneider Electric and Siemens.

Technologies and Equipment

Technologies include alternating current (AC) and high-voltage direct current (HVDC) links, FACTS devices, synchronous condensers, and series/parallel compensation. Notable HVDC schemes connect regions via projects like the Pacific DC Intertie, the China Southern Power Grid expansions, and undersea links such as the NorNed cable. Equipment innovations come from research institutions and companies including Electric Power Research Institute and National Renewable Energy Laboratory. Protection and control employ relays from manufacturers like SEL (Schweitzer Engineering Laboratories) and standards set by bodies such as IEEE.

Losses and Efficiency

Transmission losses arise from conductor resistance, corona discharge, dielectric heating in cables, and transformer inefficiencies; mitigations include higher voltages, HVDC conversion, improved conductor materials, and reactive power compensation. Historical conductor developments trace to advances by firms like Alcoa and research at institutions including Massachusetts Institute of Technology and Imperial College London. Economic evaluation of losses feeds into tariff and investment decisions by regulators such as Ofgem and Federal Energy Regulatory Commission.

Reliability, Stability, and Protection

Ensuring reliability and stability involves N-1 contingency planning, voltage and frequency control, and wide-area monitoring using synchrophasors from projects led by North American SynchroPhasor Initiative and standards from NERC. Major blackouts—investigated by commissions like those convened after the Northeast blackout of 1965 and the Northeast blackout of 2003—drove reforms in protection, coordination, and investment. Protection schemes use reclosing, distance relays, and circuit breakers supplied by companies such as Hitachi Energy.

Environmental and Economic Impacts

Transmission development influences land use, visual landscape, cultural sites overseen by agencies like the National Park Service, and ecosystems affected near projects such as crossings of the Amazon River basin or alpine routes in Switzerland. Economic impacts include capital investment decisions by utilities like Duke Energy and regional development tied to interconnection capacity, with policy shaped by bodies such as the European Commission and national ministries including U.S. Department of Energy and Ministry of Power (India). Public debates involve stakeholders from indigenous groups, municipal governments, and environmental organizations including World Wildlife Fund.

Category:Energy infrastructure