Watch the video above for a basic explanation of the service (provided by ENTSO-E and Coreso).
Purpose
One of the Nordic RCC’s tasks is to calculate cross-border transmission capacities to maximise the transmission capacity offered to the market. In the internal energy market, electricity is traded freely across borders. However, the limits of transmission capacity, i.e. the physical limitations of the transmission grid, have to be respected.
October 2024 marked the change to a new method for calculating capacities in the Nordics The Flow-based method is designed to handle the green energy transition, accommodating the increased share of renewable energy, such as wind and solar power, in the electricity system. This method allows for more flexible grid use, taking advantage of the weather-dependent nature of renewable energy production and the growing need for electricity transmission between neighbouring countries.
From NTC method to Flow-based method
Prior to the go-live of the Flow-based methodology, capacities were calculated using the Net Transfer Capacity (NTC) method.
The Net Transfer Capacity Calculation method is based on a simplified representation of the power grid and is performed by each TSO individually based on forecasted grid conditions considering worst case scenarios. In short, each TSO performs internal grid power flow calculations and reflects the internal constraints on the NTC capacity given
to the bidding zone borders. When a bidding zone border is shared between two TSOs, each TSO proposes an NTC value per direction on that border, and the most restrictive value is the one that prevails leading to more conservative results. These values are sent to the market as a constraint.
The Flow-based Capacity Calculation method is done on a Common Grid Model (CGM) — a combination of the four Nordic Individual Grid Models (IGM) which is a more detailed representation of the power grid and considers the physics of electricity flow in a more accurate way. The TSOs identify key parts of the grid, called Critical Network Elements (CNEs), and their related Contingencies (CNECs).
The Flow-based method calculates the maximum flow allowed without overloading any element. The market receives this information as Remaining Available Margins (RAMs), which show the free megawatts on each CNE or CNEC. It also includes Power Transfer Distribution Factors (PTDFs), which indicate how sensitive a CNE(C) is to changes in its bidding zone’s net position.
For further information, see the site on Flow-based.
Geographical scope
For the Nordic Capacity Calculation Region (CCR), the Nordic RCC provides the CCC service as described above.
HANSA CCR
In cooperation with TSCNET, Nordic RCC also provides the CCC service to the HANSA CCR. This region consists of the interconnectors from the Nordic CCR to the CORE CCR (Central Europe). In practice, Nordic RCC delivers the CCC service for the interconnectors at the Swedish-Polish border and the Danish-German border. In the future, Nordic RCC will also provide the CCC service to the interconnector at the Swedish-German border (owned by Baltic Cable AB).
The methodology for calculating capacities in CCR HANSA will be based on the so-called coordinated NTC.
Overview of the Nordic RCC CCC service
