Parameter sensitivity and dynamic characteristic analysis of bulb hydro generating unit with shaft crack fault

Abstract

The shaft crack fault of hydro generating unit (HGU) has a serious threat to the reliability and security of the hydropower station. However, the parameter sensitivity, operation stability and dynamic characteristics of HGU considering the shaft crack fault are rarely studied. In view of this, taking the bulb hydro generating unit (BHGU) as the research object, a nonlinear dynamic model of the BHGU under the shaft crack fault is firstly established here. And Newmark-Newton-Raphson method is used to solve this high-DOF model. Furthermore, the proposed model is also verified by comparing with existing models. Then, the parameter sensitivity of the BHGU with the shaft crack fault is analyzed via Sobol method. Meanwhile, ranks of parameter sensitivity for the vibration displacement and unbalanced forces are respectively obtained. Finally, based on sensitivity analyses, effects of some typical sensitivity parameters on dynamic characteristics of the BHGU are discussed in detail including parameters related to the shaft crack, unbalanced magnetic pull, mass eccentricity and unbalanced hydraulic force. And some stability ranges and dynamic evolution characteristics of the unit are gotten. More importantly, proposed dynamic models and analysis results can provide a guidance for the operation and maintenance of the BHGU with the shaft crack fault.