Curve fitting analysis of distribution fuse links using the cross-validation technique

This work shows the application of the Cross-Validation technique to determine the best degree for a polynomial function that fits minimum melting and total clearing curves of distribution fuse links. This technique consists of iteratively partitioning the data set, separating test points and training points on each iteration. The latter are used to perform the regression and the first to determine the quality of the obtained solution. With this, it is possible to obtain models that generalize and predict with good reliability the expected behavior. The proposed approach was implemented in MATLAB and, from the obtained equations, the maximum selectivity current between preferred type K fuses was calculated, which differed from those reported by Companhia Paulista de Força e Luz in document GED-2912. This result points to the need to review the mentioned document, which is used as reference for selectivity studies in Brazilian distribution networks.