Nonlinear dynamics of short-span electrical conductor cables under uniaxial periodic excitation

This paper is on nonlinear dynamics of flexible conductors that interconnect equipment in high-voltage substations. Such nonlinear dynamics play a role in the response of substation equipment to earthquake excitation, and characterizing them is important when considering seismic safety of substation equipment in codes of practice. The focus of this paper is on nonlinear dynamic effects in individual conductors; implications for interconnected system response are a topic of our current work. Four conductor types are considered at different levels of slack, and subject to uniaxial harmonic excitation of multiple frequency–amplitude combinations. It is observed from experiments that a large variety of nonlinear dynamic behaviors occur, depending on slack level, excitation frequency and amplitude, resulting in significant out-of-plane motion and large conductor terminal forces. To explain some of these nonlinear effects, a simplified mathematical model is described, and 2:1 resonance is demonstrated using perturbation and continuation methods. Equipped with this understanding of individual conductor nonlinear dynamics, interconnected system dynamics can be better characterized towards adapting recommended practices for seismic design of substation equipment. •Short-span flexible bus conductors exhibit a large variety of nonlinear dynamics.•Conductor nonlinear dynamics affect seismic responses of interconnected equipment.•Large conductor terminal forces occur at the stability transition boundary.•The nonlinear dynamics vary as a function of slack, input frequency and amplitude.•The 2:1 resonance is demonstrated using perturbation and continuation methods.