Nonlinear damping characteristic analysis of hydropower systems based on a reliable damping quantification method.

This paper aims to study the nonlinear damping characteristic of hydro-turbine governing systems (HTGS) in various frequency bands and improve the reliability of nonlinear damping quantification. Firstly, an HTGS model including multiple hydraulic-mechanical nonlinearities is established using an actual hydropower system as the object. Then, a trajectory quantification method is proposed to enhance the accuracy and stability of the damping calculation. On this basis, the influence of the hydraulic and controller parameters on the HTGS damping in the ultra-low and low frequency band is analyzed. Finally, a deviation indicator is defined to analyze the contribution level of each nonlinear factor to the damping characteristics, and the action mechanism of dominant nonlinearity on damping is further investigated. The results show that increasing the controller parameter and hydraulic parameter decreases the minimum damping of the HTGS. The total deviation of damping under the influence of nonlinearity reaches 1.31 times. Among them, water system nonlinearity and governor delay are two major nonlinearities, and their influence on damping characteristics accounts for 41.4% and 34.4% of the total nonlinear influence, respectively. This paper provides a powerful tool to quantify the damping of nonlinear HTGS and potentially supports the regulation performance enhancement of HTGS. [Display omitted] [ABSTRACT FROM AUTHOR]