Modeling of Dynamic Current Distribution in REBCO Insulated Coils Using a Volume Integral Formulation for Protection Purpose

Dynamic current distribution in HTS coils submitted to current ramps induces a varying inductive voltage, which can be problematic for safe quench detection as its order of magnitude may hide the increasing dissipative voltage appearing at the beginning of a transition. In order to estimate the transient voltage component, which depends on the coil geometry as well as the current profile and the coil magnetization state, we developed a model using a Volume Integral formulation based on a generalization of the Partial Element Equivalent Circuit method. The objective is to split the coil's voltage end-to-end value into an inductive and a dissipative component so as to evaluate a safe voltage threshold value to implement in the detection system, enabling early transition detection to prevent the coil from major damages. The model is compared to experimental data and its application to coil's protection is detailed on a small-scale test coil.