Editorial - VGB PowerTech Journal 1-2/2021

Transmission system operators prevent blackout – Decisive contribution by dispatchable power plants

As a result of the separation, there was a power deficit of approx. 6,300 MW in the north-west region, combined with a frequency drop to 49.74 Hertz, and a power surplus of approx. 6,300 MW in the south-east region, combined with a frequency increase to 50.6 Hertz. After only 15 seconds, the frequency deviations initially stabilised at 49.84 and 50.3 Hertz.

Shortly after 3 p.m. Central European Time, the two grid areas were synchronised again.

In Germany, the measure had no negative effects. Here, at the time the disruption occurred, electricity consumption of around 62,000 megawatt hours (MWh) was almost 2,000 MWh higher than domestic generation, so that electricity imports from neighbouring countries were necessary. Due to the dark doldrums that prevailed on that day, more than 80 % of this electricity demand of around 70,000 MW was covered by conventional power plants.

Nicht zuletzt durch das nach der letzten Netzstörung in 2006 eingeführte European Awareness System (EAS) konnte ein größerer Blackout verhindert werden. Auf dieser Plattform können die Netzbetreiber Betriebsdaten in Echtzeit austauschen. Insgesamt verweist die Störung, auch wenn die Ursachenanalyse noch nicht abgeschlossen ist, dennoch auf steigende Risiken für die Sicherheit der europäischen Stromversorgung, wenn im Zuge der Energiewende zunehmend regelbare Kraftwerksleistung vom Netz genommen wird.

A major blackout was prevented not least by the European Awareness System (EAS) introduced after the last grid disturbance in 2006. On this platform, the grid operators can exchange operating data in real time. Overall, even if the analysis of the causes has not yet been completed, the disturbance nevertheless points to increasing risks for the security of the European electricity supply, if, in the course of the energy transition, more and more controllable power plant capacity is taken off the grid.

A further frequency collapse into more critical areas could essentially be prevented by the available instantaneous reserve, i.e. the moment of inertia of the rotating masses of the turbines and generators in the power plants still in operation.

Furthermore, more than 4,000 MW of the additional capacity needed in the North-West region was provided by increasing the output in power plants that were ready for use for primary and secondary control power and minute reserve.
So far, alternatives for these system services are only available to a very limited extent.

In Germany, the controllable generation capacity will be reduced from about 98,000 MW in 2020 to only 80,000 MW in 2023 due to the nuclear phase-out, which is on the home straight, and the phase-out of coal-fired power generation, which has already begun. The highest grid load in 2020 was around 83,000 MW and, as expected, will not be reduced in the coming years due to rising electricity demand. The hope of politicians that they will always be able to compensate for this power shortfall by importing electricity is subject to the proviso that there will also be a decline in secured generation capacity in our neighbouring European countries as part of the energy transition. Necessary replacement investments in secured capacity, e.g. on the basis of natural gas, are only promoted to a limited extent, at least in Germany, due to the unfavourable regulatory framework conditions.

In the interest of maintaining a high level of security, of supply it would be advisable for German policy-makers to follow the advice of experts and, figuratively speaking, at least install a brace before cutting the belt completely.