transmissionssystemoperatører

Transmissionssystemoperatörer (transmission system operators, TSOs) are organizations responsible for the operation and development of a country's high‑voltage transmission network, primarily in the electricity sector and, in some cases, in the gas sector. They ensure reliable system operation, security of supply, and balance between generation and consumption.

Core duties include real-time grid operation, frequency control and balancing, congestion management, and capacity allocation for cross-border and domestic transmission. They monitor the grid, perform risk assessments, plan and implement network expansions, maintain critical assets, and coordinate with market participants to enable efficient electricity markets. They also publish grid data and participate in contingency planning and emergency procedures.

Regulation and market context: TSOs are typically required to operate in an independent, non-discriminatory manner and are overseen by national energy regulators. In the European Union, TSOs coordinate under market codes and via ENTSO-E (for electricity) and ENTSO-G (for gas). They work with neighboring TSOs to manage interconnections and cross-border trade.

Examples: in Sweden, Svenska Kraftnät is the TSO for the electricity grid; in Denmark, Energinet; in Norway, Statnett; in Finland, Fingrid. The term can also apply to natural gas transmission networks and, in some contexts, to telecommunications or railway systems, though these sectors often have different regulatory structures.