aFRR stands for automatic Frequency Restoration Reserve and refers to a mechanism used to maintain the frequency of the electricity network. It is one of the reserves used by the national grid operator to guarantee the stability of the network.

The aFRR is a form of secondary reserve, meaning it is activated when an unexpected change in the network's frequency occurs. When the frequency deviates too much from the nominal value of 50 Hz, the aFRR is activated to restore balance by adjusting the power available on the network.

Control capacity can be upward or downward regulating: upward aFRR and downward aFRR. Upward aFRR is activated when the network frequency is too low, meaning more power is needed to restore balance. This may be the case, for example, when there is an unexpected increase in demand for electricity or when a power plant malfunctions. Downward aFRR is activated when the network frequency is too high, meaning less power is needed to restore balance. This may be the case, for example, when there is an unexpected drop in electricity demand.

Up-regulating aFRR can be achieved through various sources, such as wind turbines, and batteries or by consuming less energy.

Who can participate?

An asset capable of producing or consuming electricity.
An asset that can adapt its electrical power linearly.
An asset capable of modulating its electrical power.
* The asset must be able to increase (aFRR UP) or decrease (aFRR DOWN) its production within 7.5 minutes of receiving a linear signal transmitted every 4 seconds.