Fluctuations between the injection and withdrawal of electricity in the grid must be constantly balanced by suppliers of balancing energy increasing or decreasing power plant output at short notice. A distinction is made between the balancing energy resources frequency containment reserve (FCR), automatic frequency restoration reserve (aFRR) and manual frequency restoration reserve (mFRR). These balancing energy resources differ in terms of activation rate and change speed. FCR and aFRR are automatically called up from controllable power plants. mFRR is requested manually from suppliers.
FCR must be provided within 30 seconds, aFRR within 5 minutes and mFRR within 10 minutes, in the required amount in each case.
The FCR to be reserved is organised via auctions held by Austrian Power Grid AG.
The aFRR is activated automatically to relieve the FCR and free it up to perform its grid balancing function again.
The aFRR and mFRR markets are also organised by Austrian Power Grid AG. The costs for the aFRR provided are passed on from APCS to the balance groups via the imbalance energy.
mFRR is requested by instruction from the supplier. It is used in the event of prolonged use of aFRR, particularly after power plant failures, in order to replace the aFRR and free it up for new balancing processes.
In order to ensure sufficient quantities of balancing energy, so-called market makers are permitted in the APG control area in addition to balancing service providers; these guarantee sufficient quantities for the balancing energy market within the framework of a weekly market maker tender, thus ensuring sufficient supply to the system.
Imbalance energy quantities resulting from unintended exchange are raised in weekly tendering processes via the Austrian electricity exchange EXAA Energy Exchange Austria and returned in the form of compensation.
APCS passes on the costs of balancing energy (excluding FCR) to the balance groups via imbalance settlement and provides all information on the various balancing energy tenders (bid overview, bids called, tender details, etc.) for all registered balancing service providers on the APCS clearing platform.
Balancing energy
Frequency containment reserve
Description
The frequency containment reserve (FCR) is needed to automatically compensate for any imbalance between generation and consumption within a few seconds by activating (regulating), thereby stabilising the frequency. In the continental European grid, a FCR of +/-3000 MW is constantly maintained. Each control area contributes a share corresponding to its annual generation. The FCR to be maintained by the APG control area is approximately +/-60 to 80 MW.
Tendering procedure
The FCR to be maintained is organized by Austrian Power Grid AG through tenders.
APCS provides all information on the tenders for all registered FCR providers in the APCS clearing platform.
The costs of the FCR are not passed on to the balance groups via imbalance energy.
Balancing energy
Automatic frequency restoration reserve
Description
The automatic frequency restoration reserve (aFRR) is activated automatically to relieve the FCR and free it up to perform its grid balancing function again. The aFRR is activated when the impact on the grid lasts longer than 30 seconds or is expected to last longer than 30 seconds. Prior to this, any overload or deficit in the grid is balanced solely by the FCR.
The required amount of aFRR depends on the size of the control area and the availability of power stations in the control area. The aFRR must be capable of compensating for the failure of the largest power station unit in the control area. In the APG control area, the largest power plant unit is covered by the aFRR in combination with the mFRR.
The capacity price of the aFRR is charged to electricity generators with an installed congestion capacity of more than 5 MW in accordance with the System Usage Fees Regulation (SNE-VO). This tariff component is called a system service. The current SNE-VO can be found on the website of the Austrian regulator at www.e-control.at.
The costs for the aFRR provided are passed on from APCS to the balance groups via the imbalance energy.
The prices of the activated aFRR are included in the calculation of the imbalance energy price.
Tendering procedure
The market for aFRR is organised by Austrian Power Grid AG. In addition to national auctions, cross-control-area cooperation has been introduced to optimise overall costs.
The ALPACA cooperation combines the power auctions of the national TSOs of participating control areas, thus creating competition between suppliers.
The PICASSO cooperation was established to activate balancing energy. Local bids are combined in a common merit order list.
APCS passes on the costs of the aFRR to the balance groups via the imbalance energy settlement. APCS provides all information on the tenders (offer overview, offers called up, tender details, etc.) for all registered aFRR providers on the APCS clearing platform.
Balancing energy
Manual frequency restoration reserve
Description
If the imbalance in the control area lasts longer than 15 minutes, the manual frequency restoration reserve (mFRR) is activated. It is activated manually and serves to relieve the aFRR so that it becomes available again.
In the APG control area, the provision of positive mFRR also serves to support the aFRR, so that the largest power plant block can be compensated for in the event of a failure without endangering grid stability.
The costs of the mFRR energy are charged to the balance groups via the imbalance energy settlement.
Negative mFRR power is invoiced to the balance groups via the additional billing mechanism (ZAM). The ZAM is a fee, which is based on generation and consumption of the balance groups.
The prices of the activated mFRR are included in the calculation of the imbalance energy price.
Tendering procedure
Tenders for mFRR are organised by Austrian Power Grid AG.
The MARI cooperation was established to activate mFRR. Local bids are combined in a common merit order list.
APCS passes on the costs of the mFRR to the balance groups via the imbalance energy settlement.
APCS also provides all information on the tenders (offer overview, offers called up, tender details, etc.) for all registered mFRR providers on the APCS clearing platform.
Balancing energy
Unintended exchange
Description
Because of technical reasons, there are differences between the target and actual values of the exchange between neighbouring electricity grids. The unintended exchange of the APG control area is the amount of energy that is unscheduled taken from or fed into the grid area of the Regional Group Continental Europe (RGCE) by the APG control area. In accordance with ENTSO-E, the excess energy withdrawn or supplied must be returned in the following week after defined tariff periods.
Tendering procedure
The quantities of unintended exchange in a week are evaluated according to tariff periods and balanced out in the following week with a compensation programme as a band delivery. In the APG control area, these energy deliveries are procured or sold via the Austrian electricity exchange EXAA Energy Exchange Austria.
APCS is responsible for the settlement of the unintended exchange.
Balancing energy
Balancing energy pooling
Description
Balancing energy pooling refers to the combination of several independent technical units (TUs) into a virtual group (pool). The technical units must meet the prequalification requirements of the control area manager for the respective balancing energy reserves. The pooling of technical units is intended to enable a broad spectrum of providers and thus ensure greater liquidity on the balancing energy market. The technical units can be members of different balance groups. However, the balancing energy pool only acts as a single supplier balance group to the control area manager. The relevant balance group representative bears financial and operational responsibility to APCS.
Schedule processing
The balancing energy call is balanced ex-post by the control area manager via a schedule. In the case of cross-balance group balancing energy pooling, the question arises as to the correct allocation of the balancing energy call. In principle, the applicable deadlines for schedule registration with APCS already allow cross-balance group balancing energy pools to be mapped without additional contractual or administrative adjustments.
As usual, the control area manager balances the balancing energy call against the supplier balance group using a schedule. The balance group representative of the supplier balance group must now ensure that the call is correctly distributed among the balance groups of the balancing energy pool within one working day (D+1 16:00). The contractual fulfilment of the call by the technical units is monitored by the control area manager or E-Control as required.
