•
21:29 -
E.ON Netz made load flow calculations and there were no indications of any violation of limit values. Without any calculations, E.ON Netz staff assumed that the
N-1 criterion would be met in the system once the Conneforde-Diele line was switched. •
21:30 - Before the Conneforde-Diele line was opened, RWE TSO's calculations showed that, even though the RWE TSO grid would be highly loaded, it would still be secure. •
21:38 - E. ON Netz switched off the first circuit of the 380 kV Conneforde-Diele line. •
21:39 - E.ON Netz switched off the second circuit of the 380 kV Conneforde-Diele line. E.ON Netz soon received several warning messages of high power flow in the Elsen-Twistetal and Elsen-Bechterdissen lines. •
21:41 - RWE TSO informed E. ON Netz that the Landesbergen-Wehrendorf line (an interconnection line between E. ON Netz and RWE TSO) was still under the given limit (1,795 A) and that the N-1 criterion was still met in the internal RWE TSO network. The protection settings on both sides of the line are different. •
22:00 - Every full hour, the commercial schedule changes were set. Consumption in E. ON Netz was about 13,500 MW and the injected wind power accounted for 3,300 MW. Due to transits, the lines towards the West were already loaded; this situation was normal. •
22:05 - Suddenly the load flow situation changed unexpectedly and resulted in a fast increase of the load on the Landesbergen-Wehrendorf line by 100 MW. •
22:06 - The current in the Landesbergen-Wehrendorf line increased to 1900 A within 2-3 minutes. The safety limit value of 1800 A (specified by RWE) was exceeded on the line. •
22:10:11 - Because of the rush, E.ON Netz made the coupling without any coordination with RWE. The switching measure was meant to reduce the load flow of the Landesbergen-Wehrendorf line. •
22:10:13 - The Landesbergen-Wehrendorf line was first tripped automatically by the protective device. The 220 kV Bielefeld/Ost-Gütersloh line and the 280 kV Bechterdissen-Elsen line were also tripped. •
22:10:28 - The UCTE SYSTEM was split shortly after the tripping of the interconnection lines between E. ON Netz and RWE TSO, internal E.ON Netz lines, internal lines in APG (AT), interconnection lines between HEP (HR) and MAVIR (HU), and the internal lines in HEP (HR) and MAVIR (HU). •
22:10:32 - All interconnection lines between Morocco and Spain tripped due to the low frequency. == Affected areas ==