Transmissionssystemet

Transmissionssystemet, in the context of electricity supply, refers to the high‑voltage transmission network that transports electric power from generators to distribution networks and large consumption centers. It forms the backbone of the electricity system, ensuring long‑distance transfer, reliability, and cross‑border interconnections.

The system comprises overhead lines, underground cables, substations, and transformers operating at high voltage levels, typically above distribution voltages. It also includes interconnectors and, in some cases, high‑voltage direct current HVDC links that enable long‑distance or bi‑directional transfer between asynchronous grids. Control and protection equipment, SCADA systems, and grid automation support real‑time operation and fault management.

In Sweden, Svenska Kraftnät functions as the transmission system operator (TSO). The TSO is responsible for maintaining reliable operation, planning network expansion, and coordinating with neighboring countries and TSOs through the European network of TSOs, ENTSO‑E. The European electricity system is designed to maintain frequency (about 50 Hz in most of Europe) and voltage within tight limits, balancing supply and demand in real time and managing reserves and contingencies.

Key responsibilities include system security and resilience (N‑1 criteria and restoration procedures), non‑discriminatory access for market participants, and tariff and capacity management. Planning efforts focus on integrating more renewable generation, reducing congestion, and extending interconnectors to improve cross‑border trade and reliability. The transmissionssystemet thus plays a central role in energy security, market operation, and the transition toward a more interconnected and sustainable grid.