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Balancing reserve types in detail

Overview of balancing reserve types.

FCR, aFRR and mFRR form a three-stage control system that keeps the grid frequency in Germany stable. The FCR reacts fastest and autonomously to frequency deviations, while aFRR is automatically activated to compensate for persistent deviations. The mFRR serves as the last instance and is manually activated to correct major deviations.

Balancing capacity and balancing energy are two different aspects of the provision of balancing services.

  • Balancing capacity refers to the provision of capacities that can be used to stabilize the electricity grid.
  • Balancing energy describes the actual activation of these capacities and the associated amount of energy that is fed in or taken from the grid for frequency regulation.

In case of FCR, remuneration is only paid for the provision of balancing capacity. This covers the costs of reserving capacity for FCR, regardless of the balancing energy actually activated. The continuous and decentralized provision as well as the associated difficulties in the precise measurement of balancing energy make a separate remuneration impractical.

Remuneration of balancing reserve types.

In the case of aFRR and mFRR, remuneration is paid both for reserved capacity and activated balancing energy. Suppliers who have been awarded a contract in the balancing capacity market will then also have to submit a bid in the balancing energy market. In addition, providers who have not been awarded a contract in the balancing capacity market or did not place a bit before can also operate in the balancing energy market. These so-called "free bids" are bids on the balancing energy market without an obligation to bid through a bid in the balancing capacity market.

FCR (Frequency Containment Reserve) product details
  • Definition: FCR (primary reserve) is the fastest balancing services that reacts directly and decentrally to frequency changes without the need for an explicit call to the TSOs.
  • Delivery time: FCR is the fastest balancing services and must be fully delivered within 30 seconds of the occurrence of a frequency deviation.
  • Duration of performance: FCR service must be able to be provided continuously for two hours. Requirements for plants with limited capacity, see below.
  • Procurement: FCR is procured in a joint, cross-border tender process with many neighboring countries, see also International Cooperation.
  • Product length: Product length for FCR is four hours.
  • Symmetrical product: FCR is procured as a symmetrical product, which means that providers must be able to provide both a performance increase and a decrease in performance in the amount of capacity bidded.
  • Technical requirements: The FCR provision must be carried out independently by each individual Technical Unit (TE) according to the mains frequency deviation.
aFRR (automatic Frequency Restoration Reserve) product details
  • Definition: aFRR (secondary reserve) is automatically activated to compensate for frequency deviations.
  • Speed of delivery: aFRR must be activated completed within 5 minutes after activation signal.
  • Delivery time: aFRR service must be able to be provided continuously for the entire product length of four hours. Requirements for plants with limited capacity, see below.
  • Procurement: aFRR balancing capacity is put out to tender daily in Germany. There is an existing balancing capacity cooperation with Austria, where bids that have not been awarded in one country can be used by the other country, see International Cooperations. The aFRR balancing energy is procured via the PICASSO platform with many neighbouring countries, see International Cooperations.
  • Product length: As with FCR, product length for aFRR balancing capacity is four hours. The product length of aFRR balancing energy is 15 minutes.
  • Separate tendering: In contrast to FCR, positive and negative control reserves are tendered separately for aFRR.
  • Possibility of pool formation: With aFRR, the formation of pools is possible, whereby the pool management controls the individual units in such a way that the setpoint specified by the TSO is achieved over all units.
mFRR (manual Frequency Restoration Reserve) product details
  • Definition: mFRR (tertiary reserve) is activated manually to compensate for larger frequency deviations that could not be compensated for by FCR and aFRR.
  • Speed of delivery: mFRR must be completely activated within 12.5 minutes after activation signal.
  • Delivery time: As with aFRR, it must be possible to provide mFRR continuously for the entire product length of four hours. Requirements for plants with limited capacity, see below.
  • Procurement: mFRR balancing capacity is put out to tender daily in Germany. mFRR balancing energy is procured via the MARI platform with many neighbouring countries, see International Cooperations.
  • Product length: As with aFRR, the product length is four hours for mFRR balancing capacity and 15 minutes for mFRR balancing energy.
  • Separate tendering: As with aFRR, positive and negative balancing reserves are tendered separately for mFRR.
  • Technical requirements: mFRR enables block offers that are indivisible when awarded.
Capacity of systems with energy storage.

Potential activation for units with limited capacity:

The minimum working capacity of the energy storage system must reach or exceed two differently defined lower limits.

  1. The minimum capacity of the energy storage unit relative to the PQ power shall be 15 minutes each per product FCR and FRR.
  2. The minimum capacity of the energy storage unit relative to the marketable power for FCR shall be 15 minutes. However, both previous activations and storage management measures must be taken into account (seePQ conditions section 3.1.5 for details). In the case of the FRR, the minimum capacity of the energy storage system relative to the marketable power shall be 60 minutes. (This requirement does not apply to exclusive participation in the balancing energy market - in this case, the actual marketing period on the balancing energy market must be taken into account. Any up and down ramp before and after the relevant product time slice must be included energy wise.)