Why has it happened again? Comparison between the UCTE blackout in 2006 and the blackouts of 2003

The paper starts with an overview of, and comparison between, the UCTE blackout of 2006 and year 2003 blackouts in the US and Italy. The main conclusion of the paper is that the European utilities have not really learned the lessons from the blackouts of 2003. Increased liberalisation of electricity supply industry has resulted in a significant increase in inter-area (or cross-border) trades which often are not properly accounted for when assessing system security. The traditional decentralised way of operating systems by TSOs, with each TSO looking after its own control area and little information exchange, resulted in inadequate and slow response to contingencies. A new mode of coordinated operation for real-time security assessment and control is needed in order to maintain system security. This new mode of operation requires overcoming a number of organisational, psychological, legal and technical challenges but the alternative is either to risk another blackout or run the interconnected system very conservatively, maintaining large security margin at a high cost to the consumer.