Date: 11. Jan. 2021. - Notices
On Friday, 8th January 2021 the synchronous area of Continental Europe was split into two separated grid regions for more than an hour. Frequency deviation was registered in the power system of BiH and in neighbouring systems. The separation occurred at 14h 04 CET over control areas of Romania, Serbia, Bosnia and Herzegovina and Croatia and at 15h 08 CET it was reconnected. The separation was caused by cascading outages of transmission lines in the South East Europe. In BiH these lines had outages: 220 kV Prijedor 2 – TPP Sisak and Prijedor 2 – Međurić. In a newly formed synchronous area of the South-East Europe frequency increased up to 50,61Hz which was a direct consequence of more generation power than the load power at that time.
Due to overfrequency protections system in the EES BiH, certain generation facilities were immediately disconnected from the transmission system thus reducing frequency and preventing further outages or a total breakdown of the system. In order to create conditions for resynchronisation, as NOSBiH requested, generation in BiH was additionally reduced and another generators at the hydro power plants at Rama, Čapljina, Grabovica and Višegrad were also disconnected.
After the preparatory actions for the resynchronisation were taken, Croatia’s TSO (HOPS) at 15h 07 CET switched on the busbar coupler at the TPP Ernestinovo and the two newly formed synchronous areas were reconnected. With this resynchronisation the state in the EES of the Continental Europe was back to normal. After this first step was successful, OHL 400 kV Novi Sad – Subotica, OHL 400 kV Konjsko – Velebit, OHL Prijedor 2 – TPP Sisak and Prijedor 2 – Međurić were switched on. With the coordinated action of the South East system operators and ENTSO-E, the electric power system of the Continental Europe was stable soon and most European countries did not even feel the incident.
NOSBiH will, through its working groups within the ENTSO-E, participate in an overall analysis of the incident and the course of events, and analyse in detail the situation in the EES BiH, mostly in the domain of protection and other relevant indicators.