On Friday, 8 January 2021, the Continental Europe Synchronous Area was separated into two areas (the North-West area and the South-East area) due to cascaded trips of several transmission network elements.
European Transmission System Operators (TSOs) immediately started to resolve it and resynchronised the continental Europe power system. Due to the fast and coordinated approach, no major loss of load or damages were observed.
According to the Interim Report published by ENTSO-E (the European Network of Transmission System Operators), the overall pan-European flow pattern on that afternoon reflected a special load situation. A situation that was caused, on one hand by warm weather in the Balkan Peninsula as well as the Orthodox Christmas holiday on 6 and 7 January, leading to an overall lower demand than usual in some of these countries. On the other hand, countries in central Europe saw colder weather and corresponding higher loads.
The overall pan-European flow pattern was complemented by additional local flows, leading to an increase of flows within the Croatian transmission system, especially near the substation Ernestinovo.
As explained in the report, to understand further impacts on the market, comparisons of the commercial and cross-border physical flows from the South-East area to the North-West area and day-ahead prices for these areas have been compiled and data trends indicated that the market was not interrupted, nor that prices fluctuated, both at the time of the incident and afterwards. In addition to this, TSOs from the affected South-East area highlighted that no market activities were suspended at the time of the incident.
ENTSO-E reported that the incident can be classified as a scale 2 incident according to the ICS (Incident Command System) methodology. For a scale 2 incident, a detailed report must be prepared by an expert panel. It is currently planned that the expert panel will start its investigation this week and it will be summarised in a final report this summer.
In order to understand the root causes of the incident and to evaluate the incident as soon as possible, the TSOs have already prepared as a next step an analysis based on questions on why this incident could not be avoided and which existing defence measures worked well in order to prevent the power system from further disturbances.