Metodologia de detecção e seleção de fases para faltas de alta impedância através da relação angular de componentes simétricas

Abstract

This paper proposes new detection and phase selection methods for high impedance faults in distribution networks. Both methods are based on a phase selection methodology developed for transmission lines, which was adapted for high impedance faults. The detection and phase selection methods use two different coefficients obtained from symmetrical components of current signals measured at the substation. The first coefficient is calculated by the angular difference between the negative and positive sequence, while the second is obtained by the angular difference between the negative and zero sequence. By monitoring these coefficients calculated for fundamental frequency and third harmonic, it is possible to detect the fault and also determine the faulted phase. The performance of the proposed methods was evaluated by simulations on a test system based on a real distribution feeder. The results were presented considering four different high impedance fault configurations, an aspect rarely addressed in this branch of knowledge. The methods were also evaluated for load unbalance, several high impedance surfaces, different distances between fault and substation, and transients from capacitor switching events. The results showed a good performance of the proposed methods highlighted for not suffering considerable load unbalance influence, a common feature of distribution feeders.