Balancing the system

Managing an electricity transmission network that permanently supplies 30 million residents 24/7 is a mammoth task and a huge responsibility. The Elia Group takes this role very seriously and operates its system as safely and efficiently as possible at all times.

The grid frequency is a continuously changing variable. Supply and demand have to be managed from one second to the next: when demand rises or decreases, the control centres activate reserves or call on suppliers and generators to make up the difference and keep a balance.

Control Centres

The heart of system operations are the Control Centres of Elia and 50Hertz in Brussels and Berlin. International delegations from all over the world regularly visit the Control Centres of the Elia Group to witness the real-time operation of a heavily used electricity system and the secure integration of the worldwide highest shares of volatile renewables.

To keep at the edge of this evolution, the control centres are permanently evolving with powerful real-time calculation and steering tools, streamlined processes involving hundreds of partners and the most modern forecast methods for wind and solar infeed. 

Security of supply

Despite the fact that transmission system operators are not responsible to supply the customers with electricity, they play a crucial role for keeping security of supply while running a reliable electricity system. Balancing the electricity system has nowadays become quite challenging as volatile generation - such as wind and solar power - became a bigger part of the overall energy mix. In spite of the dynamic and radical changes in the energy landscape, both Elia and 50Hertz manage to keep their interruption rates very low.
Development of the fault rate of 50Hertz Graph: Development of the fault rate of 50Hertz
Development of the Average Interruption Time (AIT) of Elia Graph: Development of the Average Interruption Time (AIT) of Elia
Continuity of supply in Belgium remains at a high level, among the best in Europe. The average number of interruptions on the Elia grid per consumer (Average Interruption Frequency) in 2013 was 0.0891, equivalent to one interruption per customer every 11.2 years. Across all customers, the average duration of interruptions was 2 minutes and 29 seconds per customer, equivalent to an average availability of more than 99.999%. However, Elia is facing a very tight supply situation during the winter 2014/15 due to many outages of power plants.

See measures to master the winter situation in Belgium on

Integration of fluctuating renewables

The integration of a rapidly growing share of electricity generated by renewables is a major challenge for system management since electricity inflows from renewables are harder to predict and their infeed can vary very quickly (changes in the regions of the Elia Group can reach approximately 2 GW within 15 minutes).

Renewable energy sources are dependent on wind and sun and thus provide a very unsteady electricity input. This volatile electricity input increases the complexity of maintaining the balance between generation and consumption and on keeping safe operational conditions.
wind infeed fluctuations in the grid of 50Hertz Graphs: wind infeed fluctuations in the grid of 50Hertz
For that reason, the TSOs of the Elia Group use reserves and intervene into the behavior of producers to avoid overloads in the electricity system, while requiring them to raise or lower their output. This happens many times a day.