Abstract
This paper presents initial work on utilizing controlled short-circuit tests for identifying sufficiently accurate electric circuit models of batteries, aimed at fault analysis in power grids featuring large battery storage systems. The goal is to derive the models by testing components of the battery system, circumventing the need for full system short-circuit tests. These models are essential for the design of protection devices and the sizing of batteries and connected systems. A technique for determining the electric circuit parameters of batteries through controlled tests is presented, utilizing publicly available Python libraries. This technique also determines the parameters of the equipment employed to conduct the short-circuit tests. Validation was carried out through two scenarios: one involving a single cylindrical cell and another with 12 cells connected in series. The analysis of the identified admittances revealed difficulties in accurately predicting the short-circuit currents of battery modules based on single-cell models. In addition to the dependency on state of charge, geometry-dependent inductance plays a key role. In a compact arrangement of 12 cells, there was a 38 % difference between the equivalent inductance calculated by summing the 12 single-cell models in series and the inductance identified for the actual 12 -cell arrangement. This demonstrates that calculations of battery module short circuits that rely solely on single-cell characteristics can result in inaccurate estimation of initial time derivative and peak magnitude of the fault current, due to the mutual coupling among the individual cells, particularly in larger modules with several cells arranged in series and parallel.