Experiences and future plans in monitoring the inter-area power oscillation damping

This paper first describes what kind of inter-area oscillations there exist in the Nordic power system and in what kind of situations they affect the power transfer capacity. The paper also describes the actions already taken in order to improve the damping of the oscillations and the efforts at online-monitoring of the damping level. The results of a two yearpsilas monitoring period imply that one should have different approaches to frequent small and infrequent large power oscillations. The first one of these is more difficult in nature and requires system-wide synchronised phasor measurements combined with a solid mathematical method to reliably calculate the damping level. Some plans are presented that are based on using several input signals measured from different points of the grid and using a known probing signal to excite oscillations during the normal operation of the power system.