Nordic Common Grid Model Alignment
The NCGMA service provides the TSOs with information that allow them to create Individual Grid Models (IGMs) that fit together in the process of merging them into the Common Grid Model (CGM).
The market provides information on flow on bidding zone border connections in time horizons shorter than two days ahead of operation, in the spot market the day ahead and in the intraday market, intraday. In time horizons longer than this there are no market results available which leaves the CGMs to be built based on forecasts from the TSOs.
All the European TSOs forecasts are in the pan European Common Grid Model Alignment (CGMA) process aligned to create a system in balance, with a total power production equal to the total load in the system.
The forecasts on load and power production are in the NCGMA service collected from the four Nordic TSOs and aligned into a common Nordic forecast on net position (balance in an area, where a positive net position means the area is a net exporter of power) and power flow on each of the bidding zone borders. This forecast, that is created in a preprocess to the European CGMA, is sent as input to the pan European calculations and aligned with the rest of the European system.
A post process to the European CGMA service is run in the NCGMA service after the CGMA results are finalized. Power flow on HVDC connections are in this post process divided into flow on each of the poles constituting the HVDC connection (e.g. the Skagerrak link between Norway and Denmark has 4 physical poles/cables), and losses on the connections are calculated. By utilizing this information in the creation of the IGMs, they are guaranteed to contain the correct flow on each of the poles. Similarly, the net position given by the CGMA process of the Swedish and Norwegian control areas are divided between the four Swedish and five Norwegian bidding zones and the net positions of all the four Nordic countries are divided between the bidding zone borders before the results are provided to the TSOs. In this way the NCGMA service provides all the information needed to create IGMs that fit together.