The TSO (Transmission System Operator) is the actor responsible for the operation, maintenance, and development of the high and extra-high voltage electricity transmission network.
Its role is to ensure the secure, continuous, and balanced flow of electricity between production sites (power stations, wind farms, photovoltaics, etc.) and the distribution networks (DSO), while guaranteeing the stability of the electrical system. The TSO also ensures the real-time balance between electricity supply and demand, which is essential to prevent network outages or overloads. In the UK, this role is primarily undertaken by National Grid Electricity System Operator (ESO).
The TSO is a strategic link in the integration of renewable energies and the energy transition.