An Additional Damping Strategy Base on Central Filter for Ultra-low Frequency Oscillation Suppression

Recently ultra-low frequency oscillation (ULFO) was discovered in hydropower-dominated power systems (HDPS), such as Yunnan and Southwest Power Grid. In this paper, an additional damping control strategy for hydro-turbine Governor (HTG) is presented to eliminate ULFO. Firstly, the HTG model and transfer function is established, the mechanism of ULFO is analyzed. Secondly, an HTG additional damping controller based on the central filter structure (CFS-ADC) is designed. Finally, in the four-machine two-area system, the load disturbance and speed step experiments were carried out to verify the effectiveness of the CFS-ADC for suppressing ULFO. Compared with the additional damping controller of the common structure (CS-ADC), the simulation show that the CFS-ADC can improve the ability to suppress oscillation and to power the speediness of primary frequency regulation (PFR).