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Grid Control Cooperation

Grid Control Cooperation

The German TSOs operate a joint balancing market. To this end, they use the grid control cooperation concept, which provides for four levels of cooperation:

1. Avoidance of opposing control power activation

It is inherent in the system that there are times when individual control areas have a power shortage, while other control areas have a power surplus at the same time. Without the NRV, the control power for each control area would be activated independently of each other with different signs. The aim of Module 1 is to avoid the opposing activation of control power through controlled and targeted energy exchange between the control zones. The savings potential lies in the reduction of the opposing activation of control energy (aFRR and mFRR) and the associated costs. Via the IGCC and the PICASSO platform, this principle of netting balancing energy requirements has been extended to our neighboring European countries.

2. Common dimensioning of balancing reserve

The aim of Module 2 is the joint, cross-control area dimensioning of the balancing capacity and thus the reduction of the capacity to be provided and the corresponding costs (for aFRR and mFRR). The dimensioning is identical to a fictitious German control area. The NRV allows the participating control areas to have access to the jointly held reserves, which means that these can be reduced.

3. Joint procurement

Module 3 enables the German TSOs to procure control power across German control area borders. The savings potential lies in the cost reduction through direct competition between providers in an all-German market as well as in the reduction of the technical effort for the providers.

This module is also transferable to our neighboring countries, but the cross-border procurement of FRR requires a mechanism that ensures the necessary cross-border transmission capacity for the exchange of control power. Using the example of joint aFRR procurement with the Austrian TSO APG, the German TSOs have shown that this is possible. You can find out more about this under ALPACA.

4. Cost-optimized activation of balancing capacity

The aim of Module 4 is the economic optimization of balancing capacity activation across control areas. The savings potential therefore lies in the reduction of costs for balancing energy. To this end, all bids from all control areas are listed in a joint merit order. The requirements of all control areas are netted and the remaining balance is retrieved from the common merit order list.

The new European platforms MARI and PICASSO also work according to this principle. 

Technical functioning

The basic technical principle of the grid control cooperation is based on “aFRR optimization software”, which calculates the optimal overall aFRR deployment for the NRV. The basic principle is shown in the figure:

Due to a priori unknown fluctuations in consumption and generation, the power balance of a control area continuously deviates more or less from the required power balance. The resulting balance error must be compensated for by activating aFRR. The aFRR requirement of the participating control areas is reported online to the coordinating optimization module. This calculates a correction value, which in turn affects the power balance error. The input variable of the secondary controller changes accordingly, which as a result retrieves the aFRR quantity calculated as optimal by the aFRR optimization system from the NRV control zones at optimal cost. The correction activation is calculated online with a resolution of one second.