ENTSO-E, the association of European TSOs, has reported a severe disruption of the Continental European (CE) Power System, a large synchronised area encompassing 25 countries reachng from Spain to Turkey and from Poland to The Netherlands. The system has been experiencing a continuous system frequency deviation from the mean value of 50 Hz, since mid of January 2018 through to early March.
The power deviations have been identified as originating from the control area Serbia, Macedonia, Montenegro (SMM block) and specifically Kosovo and Serbia. The deviations have led to a slight decrease in the electric frequency average over the period.
ENTSO-E reacted by sending a strong message to the SMM block stating that “the average frequency deviation, which has never happened in any similar way in the CE Power system, must cease. The equivalent missing energy amounts currently to 113 GWh, and the question of who will compensate for this loss has to be answered.”
The decrease in frequency average has been affecting those electric clocks that are steered by the frequency of the power system, as opposed to control by a quartz crystal, and they showed a delay of close to six minutes owing to the accumulated effect of the under-frequency.
ENTSO-E has been exploring all technical options to address the deviation issue with the concerned TSOs. As there is also a political dimension with impact on the functioning of the electricity system, ENTSO-E urged European and national governments and policy makers to take swift action. These actions needrd to address the political side of this issue, supporting ENTSO-E’s and the TSOs’ actions to deliver a technical solution.
On 8 March ENTSO-E confirmed with the Serbian and Kosovar TSOs, respectively EMS and KOSTT, that the deviations which had been affecting the average frequency in the synchronous area of Continental Europe had ceased.
That was the first step in the resolution of the disruption issue. The second step is now to develop a plan for returning the missing energy to the system and putting the situation back to normal.
ENTSO-E also reports that in close collaboration with the European Commission, it is trying to identify a sustainable long term solution that will avoid a repetition of these events.
The situation experienced is unprecedented in the Continental European Power System. The European transmission system operators interact constantly, across the borders and through ENTSO-E, to ensure that security of supply is maintained in one of the world's largest synchronous areas.
For the system to properly function the frequency cannot fall below 47.6 Hz and above 52.4 Hz. At the extreme values of 47.5 (under frequency) and 52.5 (over frequency) all connected generation and devices would automatically disconnect. The average frequency of the period since mid-January 2018 until 6 March was around 49.996 Hz.
The synchronous area is made of the following countries: Albania, Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Czech Republic, Croatia, Denmark (West), France, FYROM, Germany, Greece, Hungary, Italy, Luxemburg, Montenegro, Nederland, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Switzerland and Turkey.