The source and damping of local (cc. 1.2 Hz) and inter area (0.02…0.6) Hz oscillations

Our ten years' experience has showed that a PSS realized by first order controlling stages is not efficient in 0.02...0.6 Hz frequency domain. In addition, these instruments have a disadvantage: damping the active power oscillations are the source of reactive power oscillations, which are exported into the network. So a PSS tuned 0.25 Hz are rejected by experts of power plants. This paper describes our method, revealing the source of the cc. 0.25 Hz frequency oscillations, and damping these by using a supplementary stage installed into the turbine governor. Damping oscillations in a lower frequency range we propose an appropriate setting of the turbine Static Load Frequency characteristics.