Automatic frequency restoration reserve (aFRR)
In 2013, the Nordic TSOs introduced a new type of reserve, Automatic Frequency Restoration Reserve (aFRR), in the Nordic power system. Its purpose is to return the frequency to the nominal value of 50 Hz. aFRR is a centralised automatically activated reserve. It activates based on an activation request signal sent by the TSO. The activation request is calculated based on the frequency deviation in the Nordic synchronous area and is sent every 10 seconds.
The minimum capacity of regulation is 1 MW and full activation time is 5 minutes maximum. Please see Technical requirements and prequalification process of aFRR for more information.
Fingrid procures aFRR reserve both from the hourly market and from other Nordic countries via the inter-TSO trades. aFRR is procured for certain hours during which the frequency tends to vary the most. The procurement hours are informed in advance.
A balance service provider can submit bids to the hourly market separately for up-regulation and down-regulation capacities. Capacity payment is determined based on the price of most expensive accepted bid (marginal pricing) and it is paid to the balance service provider. A separate energy fee based on actual regulation energy is paid for the balance responsible party of the reserve resource. The energy fee for up-regulation is determined according to the balancing energy market price for up-regulation, and the activation price for down-regulation is determined according to the balancing energy market price for down-regulation respectively.
A common Nordic aFRR market will be introduced in the future. However, for the time being aFRR is procured nationally. In addition, a project aiming for a common European aFRR energy market is also on-going.
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