Abstract
Modern electric power systems are large-scale systems with a complex structure comprised of interconnected networks. The balance between the generation and consumption of electricity has to be maintained at any moment. Transmission System Operator (TSO) uses ancillary services for keeping the domestic power balance. Selection of the services can be viewed as an optimization problem. In this contribution the optimization problem is solved via the Self-Organizing Migration Algorithm which belongs to the class of evolutionary algorithms. The comparison with historical activations of ancillary services showed the improved performance in terms of reduced cost for ancillary services.