Adaptive multi-scale electrothermal model of REBCO coated conductors embedded in a commercial power system transient simulator

Abstract

High temperature superconducting coated conductors (CCs) are wires with ideal nonlinear properties for use as resistive superconducting fault current limiters (rSFCLs) for power systems. However, choosing a conductor architecture that can survive all types of excitations occurring in a specific power system is a big challenge. Firstly, the non-uniformity of the critical current along the length of commercial CCs makes them prone to hot spots. Secondly, the current flowing in a CC-based rSFCL is determined by the specific dynamics of the power system in which it is installed. In order to correctly design the CC architecture, one must be able to compute the electrothermal bevahiour of CCs submitted to realistic power system excitations. This requires coupling a physically-representative CC model with a suitable commercial power system simulator. In this paper, an example of such coupling is presented, with the particularity that the numerical method used to simulate CCs can account for realistic lengths used in rSFCLs (hundreds of meters of CCs), while still being able to track hot spot developments on the micrometer scale, thanks to a dynamic adaptive meshing strategy. The coupling is realized within the EMTP-RV environment through a dynamic link library that contains the physical CC model. A few examples of applications are presented, in which propagation of multiple hot spots triggered by the power system are simulated in very moderate computation times. Besides helping rSFCL manufacturers to better select a proper CC architecture, the proposed model can also be used in regular power system simulations as an accurate rSFCL device model, which is expected to greatly help power system engineers to better plan their integration in the grid.