Abstract
Load shedding processes are widespread in hydropower stations, which has great influence on the safe and stable operation of the hydro–turbine governing system. In order to study the dynamic characteristics of the hydro–turbine governing system during the load shedding process, a novel nonlinear mathematical model of the hydro–turbine governing system is established considering the hydro–turbine system, the generator system and the governor system. In particular, a novel nonlinear mathematical model of the six hydro–turbine transfer coefficients is presented based on the definitions and hydro–turbine internal characteristics. After that, from the viewpoint of nonlinear dynamics and the practical engineering, the dynamic characteristics of the hydro–turbine governing system are investigated utilizing bifurcation diagrams, time series, Poincare maps, power spectrums and phase planes. Some meaningful results are found. The advantages of the novel nonlinear mathematical model are illustrated and commented in detail in comparison with the previous model. Finally, these models and analysis results will provide some theoretical references for the operation of hydropower stations in the load shedding transient.
Highlights
Hydraulic power, as a kind of renewable, clean, and economical resource, has been well developed in China [1,2,3]
In this study, considering that the six hydro–turbine transfer coefficients will change with the operation condition of the hydro–turbine generator unit, we propose a novel and creative calculation method of the six hydro–turbine transfer coefficients based on their definitions and the hydro–turbine internal characteristics, in which the transfer coefficients are complex nonlinear functions of the hydro–turbine head, the hydro–turbine flow, the rotational speed, and the guide vane opening
A novel nonlinear mathematical model is established for the hydro–turbine governing system (HTGS) in the load shedding transient process
Summary
As a kind of renewable, clean, and economical resource, has been well developed in China [1,2,3]. Many scholars have proposed excellent control algorithms [15,16,17,18,19,20] to adjust the hydro–turbine generator unit when some small disturbances appear, or established reasonable models to study the stability and other dynamic characteristics of the HTGS during the small fluctuation process [21,22,23]. Xu et al [23] built the Hamiltonian mathematical model of the multi–hydro–turbine governing system with a sharing common penstock under the excitation of stochastic and shock load, and discussed the stability of the system by comparing it with a real hydropower station In these studies, constant or linear hydro–turbine transfer coefficients are mainly applied to.
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