TEIAS (Turkish TSO)

Turkish Electricity Transmission Corporation (TEİAŞ) is the state-owned transmission system operator for electricity in Türkiye, headquartered in Ankara. Created in 2001 through the unbundling of the former vertically integrated utility and holding a transmission licence from the Energy Market Regulatory Authority since 2003, it is the sole owner and operator of the national transmission grid, including 66, 154 and 400 kV networks. TEİAŞ plans, builds and operates new transmission facilities, performs system operation, load dispatch and frequency control, procures and provides ancillary services, and prepares long‑term generation capacity projections and network development plans in the context of a liberalised electricity market. It transmits power from generators to 21 privately operated distribution system operators and eligible large consumers, and historically has also administered capacity mechanisms that provide additional payments to certain power plants. Operationally, TEİAŞ manages an extensive infrastructure comprising more than 70,000 km of overhead, underground and subsea transmission lines and over 1,200 substations with about 189,000 MVA of transformer capacity, supported by 22 regional directorates and 10 load dispatch control centres. Its assets include 12 mobile substations that can rapidly restore supply or meet new demand and technologies for live maintenance, helicopter inspections and submarine power cables. TEİAŞ operates Türkiye’s real‑time balancing and ancillary services markets while Energy Exchange Istanbul (EPİAŞ) runs day‑ahead and intraday trading, and TEİAŞ continues to modernise its grid through large investment programmes, including a US$750 million World Bank‑financed Transmission System Transformation project. The company operates synchronously with the continental European power system, holds observer status in ENTSO‑E, participates in regional initiatives such as SEE CAO and Med‑TSO, and is preparing the network to integrate the country’s first nuclear power plant and growing volumes of renewable generation, with an explicit corporate commitment to reliable, economical and environmentally sensitive transmission and a sustainable energy system for future generations.