The area south of this line had production surpluses at the time, which could not be transported to central Europe due to the failure of line connections. This led to a frequency increase in southeastern Europe of up to 50.6 Hz (deviation of 600 mHz) which prompted a subsequent reduction of the local production.
The opposite happened in the northern area, which also included Austria: after the grid separation the power produced in southeastern Europe was lacking and caused a deficit which resulted in a frequency drop to a value of 49.74 Hz (deviation of 260 mHz), before the local production could be ramped up and consumption reduced accordingly so that the frequency could be stabilized again.
The exact reason for the outage of the transmission system elements that led to the separation is currently subject to further investigations of expert committees of the European TSOs and their umbrella organization (ENTSO-E). For this purpose, large volumes of data from SCADA and the emergency systems of all countries have to be gathered and analyzed. From today’s perspective, the energy transition and renewable sources have nothing to do with the incident of January 8, 2021 (cf. https://www.entsoe.eu/news-events/news/).
European emergency measures proved to be efficient
In case of such a major disturbance automatic and Europe-wide coordinated “procedures” are initiated. Due to the automatic emergency mechanisms and the immediate action of all transmission system operators through their control center staff, the frequency could quickly be stabilized and returned to its normal level of operations. The main measures that were undertaken in the area of under-frequency to raise the frequency again were:
- Disconnection of contracted interruptible services (with a volume of approx. two GW in France and Italy). These services are large customers who, for an appropriate compensation, agreed to a preventive manual interruption if the frequency drops under a certain threshold. Hence, the incident did not trigger the standard automatic load shedding of end customers, which would only happen in case of larger frequency deviations (of 1.000 mHz or more).
- Activation of short-term available supportive power in various countries. Besides the aFRR that is automatically activated in all countries in case of frequency deviations, also other power plant reserves were activated in Austria.
Through these measures and the thus achieved restoration of the normal operation frequency of 50Hz (nominal frequency) the two separated grid areas could be re-synchronized at 15:08 and subsequently reconnected.
The cooperation of the TSOs on a European level and the coordination of their actions worked excellently. Within one hour normal operations could be re-established. This shows how important the Europe-wide cooperation is in terms of a European emergency mechanism. Also the lessons learned from a similar incident on November 4, 2006 have proved their value, among them in particular the “European Awareness System”, a platform which allows all European TSOs to exchange operational information (pre-defined notifications and charts / alerts) in real time to be up-to-date at all times.
A general outlook regarding the future of electricity: challenging grid situations in times of the transformation of the energy and power grid systems
Digitalization, decarbonization, decentralization and democratization are the main motors behind the transformation of the energy system. To cope with the associated challenges and at the same time guarantee the security of supply in a sustainable way, it is necessary to develop the transmission system in a holistic way and preserve or newly create capacity reserves in various areas of the system.
- Additional grid capacities (immediate grid expansion and conversion in Austria and Europe)
- Additional storage capacities
- Sufficient power plant reserves
- Additional, flexible options to compensate the volatility of renewable sources (in particular by means of digital technologies)
With the created capacity reserves, risks can be reduced and incidents like the one of last week can be counteracted in a preventive way. Similarly, also the integration of renewable energies can be ensured in a sustainable way. Thus capacity reserves are the basis for a secure and ecological power supply system and therefore the foundation for Austria and Europe as business locations and places to live.