Experimental study of nonlinear resonance galloping mechanism of transmission lines drived by non-contact electromagnetic excitation

Conducting comprehensive study on the galloping mechanism and vibration control of transmission lines is a challenge due to the uncontrollable outdoor weather and the intricate character of natural wind excitation. Consequently, this paper endeavors to develop a non-contact electromagnetic excitation system that incorporates modulation functionalities of frequency, amplitude and phase, so crucial features of galloping of transmission lines can be simulated correctly by the developed system, while maintaining controllable states. Without imposing any additional restrictions, the excitation system preserves the inherent dynamic characteristics of the transmission lines effectively. Taking a 220 kV three-phase transmission lines project in Hunan province as prototype, the test model with a geometric length ratio of 1:20 was designed according to the principle of dynamic similarity principle. By using the excitation system, single-phase or multi-phase excitation in both orientations of vertical and horizontal were implemented to the model lines, and the forced vibration tests were performed with an excitation frequency interval of 0.5-3 Hz, which revealed the nonlinear dynamic response characteristics and resonant galloping mechanism of the transmission lines.