On pitfalls of current security assessment practice in multi-area power systems

After the recent blackouts and incidents in Europe and USA, e.g. in 2003 and 2006, an increasing interest in security issues of multi-area power systems has arisen. The challenge is coordination of transmission systems operators that are responsible for their own control area but not for the whole system. Coordination is needed because often the transmission system operators have limited information on the neighboring control areas. Therefore, contingencies occurring inside one control area may not be noticed in other areas without appropriate coordination among transmission system operators even though they may have severe consequences. In this paper, we show that lack of coordination among transmission system operators may lead to insecure operation of the multi-area power system even though transmission system operators find their own control areas secure and show that security of single control areas may not imply security of the whole multi-area system. The results indicate that in order to ensure a secure operation of a multi-area power system, coordination and data exchange among transmission system operators should be improved in the future compared with the situation at the moment.