Characterization of Nonstationary Local Resonance Response of Large-Span Flexible Photovoltaic Arrays under Strong Typhoons

A strong typhoon is characterized by high-speed low pressure and spiral airflow. When the periodic excitation generated by these conditions approaches the natural frequency of a large-span flexible photovoltaic (PV) array, it may induce structural resonance. This nonstationary amplification effect may cause deformation of the interrow bracket structure, ultimately resulting in instability and potential damage to the PV array system. To elucidate the resonance characteristics of PV structures, a 5-row, 3-span fully aeroelastic wind tunnel model for flexible PV brackets was designed, along with an innovative 3D noncontact multipoint vibration measurement technique. Then, a full aeroelastic wind tunnel test was performed, factoring in wind speed changes at a 0° wind angle under the action of strong typhoons. On this foundation, the empirical wavelet transform method was employed to analyze the fluctuating and time-frequency characteristics of the wind response at typical parts of the array. Additionally, by integrating the auto power spectral density and mutual power spectral density functions, an in-depth analysis was conducted of the in-phase and orthogonal correlations between the response at the first row and those at other positions. The distribution characteristics of resonance phenomena in PV arrays were investigated using resonance components. The results indicate that under the action of a typhoon wind speed of 52.68 m/s, the structural response exhibits remarkable nonstationary characteristics and shows a low-frequency resonance mode. An amplification effect dominated by vertical bending occurs near the original fundamental frequency (1.357 Hz). The maximum vertical bending component (36.5%) and torsional resonance component (48%) are located in the first row, and the resonance component of the vertical bending response is significantly influenced by wind speed.