The Czech transmission system has been repeatedly and increasingly loaded with unscheduled north-south power flows. Whilst in past years such non-standard situations occurred relatively rarely and for a rather short term, their rate sharply increased last year. ČEPS dispatchers faced more frequently near-emergency situations in the Czech power system wherein the fulfilment of the security criteria were jeopardised.

The most critical situation occurred in the Czech transmission system in the period between 25 November and 16 December 2011, primarily due to increased unscheduled power flows which amounted up to 3500MW whilst the usual value is about 1000MW.

Crisis situations in the transmission system are usually caused by a combination of a number of factors. In this particular event, the major cause, i.e. excessive power output from wind parks in northern Germany on windy days, was combined with the following factors:

• Shutdown of eight nuclear power plants in northern and southern Germany.
• Increase of installed capacity in photovoltaic power plants in Germany.
• Intensive electricity trading, especially on spot markets.
• Increased electricity imports in the Balkan countries due to water deficit at hydro power plants in the region. 

ČEPS has long been active in cooperating and discussing this situation on the European, regional and national level and has promoted the coordination of European transmission systems’ operation and dispatch control.

The Company has implemented a number of appropriate remedial measures and introduced new tools to identify and predict critical situations. Nevertheless, the risk of the recurrence of similar situations in the future persists; to avoid the risk, transmission networks in the region must be reinforced as quickly as possible.

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