ERA modal identification method for hydraulic structures based on order determination and noise reduction of singular entropy

Modal parameter has been considered as one of the indices in assessing the working state of hydraulic structures. The method for obtaining the modal parameter indices is crucial for health monitoring of hydraulic structures. Traditionally, model parameters are measured from the prototype dynamic test under the excitation of special equipment. The preparation is time-consuming and the method is difficult to carry out. We propose a method in this paper to denoise, reconstruct, determine the order and identify modal parameters based on singular entropy (SE) of eigenmatrix. It can be used to solve the problem of system eigenmatrix order determination, and to identify the modal order and the characteristics of structures under the working state. Finally, this method is applied to identify the operational modal parameters of Ertan arch dam under different flood discharging states and vibration frequencies of the powerhouse with a two-row placed unit in Lijiaxia hydropower station during the unit halting process. This new method provides a simple way to identify the modal parameters of large-scale hydraulic structures under ambient excitation.