Research on Hierarchical Suppression Strategy for Ultra Low Frequency Oscillation of Multi machine Hydraulic Units

With the increase of the capacity of hydroelectric units, the problem of ultra-low frequency oscillation (ULFO) caused by hydroelectric units is becoming increasingly prominent. To solve the problem of ULFO in the power system with a high proportion of hydropower, this paper establishes an ASF model of "four machines and two regions" based on a detailed mathematical model of a single hydraulic unit. This study investigates the impact of multiple hydraulic turbine governor systems on ultra-low frequency oscillation in the power grid, and proposes a hierarchical ULFO suppression strategy based on participation factors and MOPSO. The final results show that this strategy effectively suppresses the occurrence of ultra-low frequency oscillations and improves the frequency recovery speed under small disturbances, providing a new approach for suppressing multi machine ULFO methods in engineering practice.