Keeping system security

Since the power lines are operating at their limits and congestion is on the rise, real-time coordination has become a key to ensure a safe supply at any time, especially with other European TSOs and with DSOs (distribution system operators).

Various measures are taken like re-dispatching, curtailing wind power, even controlled brownouts, etc. to secure the electricity system. These measures can be preventative or operative and can be employed nationally or internationally.

Measures: Activating reserves, re-dispatching, curtailing wind power and controlled load reductions

Reserve Capacities

The reserve capacities are generating capacities contracted by the transmission system operator within a short interval of time to meet demand in case of an unbalance between production and demand.

The increasing volatility in the electricity system makes the balancing of supply and demand on a real-time base increasingly demanding. The TSOs of the Elia Group have contracted different types of reserves that can be activated at any time to balance the system. They also foster the development of additional possibilities to include new players, such as windfarms, into the markets delivering reserves. The power output of a wind farm could be e.g. decreased by reducing the aerodynamic efficiency or can be completely shut down.


Re-dispatching is a particular congestion management and security measure to relieve congestions and avoid overloads of certain grid elements. The system operator intervenes in the way power plants are operated (requiring production reductions from some plants and production raisings from other plants) to solve congestion.

In recent years, the need for re-dispatch measures has increased in the area of the Elia Group since grid development is not keeping pace with the development of new generation, especially from renewable energy sources.

When re-dispatching does not fully release grid congestions and grid overloads, TSOs have as last resort to call for curtailing wind or solar power to keep the system secure.

Find more Information about  measures taken by 50Hertz

The International Dimension of system operations

The Elia Group’s grid is part of a larger, European interconnected system. To mitigate the potential risk of an unsecure system (scarce/excessive generation or low voltage quality in some regions), the TSOs of the Elia Group drive measures and initiatives in the frame of the international co-operation and co-ordination with other transmission system operators.

Coreso and TSC

The upcoming European Network Codes recognise and anticipate the need for increased coordination in terms of operational security. Moreover, they also introduce the concept of the Regional Security Coordination Initiative (RSCI) like CORESO (COoRdination of Electricity System Operators) and TSC (TSO Security Cooperation)


As major European system operators, the TSOs of the Elia Group participate in the GO15 association, a unique international organisation of of the world’s 17 largest TSOs. GO15 brings together an international network of experts who share best practices and experiences to address the challenges of the increased complexity of very large power grids by ensuring that consumer needs are met by means of providing safe and reliable power supply at reasonable costs.

The common vision and recommendations of the 17 members are shared with relevant shareholders like regulators, decision makers, manufacturers and research centers.