Devriendt C., Guillaume P., Lopez-Roldan J.

Mobile substations can be defined as completely equipped electrical substations. There is a lack of existing scientific basis in the mechanical design of the structural components of the mobile substations. There are no capabilities to determine the dynamic behaviour during transport and service conditions. Improper dimensioning of the structures results in an important degree of mechanical failures during transport. The dynamic response of structures on a mobile substation to transport-motions depends on their strength of construction, ductility, and dynamic properties. Lightly damped structures that have one or more natural modes of oscillation within the frequency band of transport excitations can experience considerable amplification of both the forces and deflections. Thus, items of mobile substation equipment whose natural frequencies lie in the normal frequency range of transport motion are particularly vulnerable to damage and fatigue. Therefore we are interested in analyzing the natural frequencies and damping ratios (modal parameters) of those components and the frequency range of transport. The analysis of the operational test data acquired during road testing requires more advanced output-only system identification methods. The output-only techniques recently developed at the Vrije Universiteit Brussel, allow for estimating the modal parameters from operational road testing data. The experimental results are compared with the results of a modal analysis applied to a finite element model of the investigated structure.