Uma revisão de modelos clássicos de faltas de alta impedância para efeito de melhoramento.

Abstract

High impedance faults (HIF) are serious and troubling disturbances in distribution systems of electric power. Due to their fault current low levels, the main power system protection devices are not able to diagnose them accurately. In this sense, HIF detection and location methods have been the focus of many researches. Such methods are often validated with the aid of computer simulations. The closer these models can reach the characteristics found in real phenomenon, the more reliable will be the diagnostic algorithms based on them. Thus, this paper presents a model of HIF which takes into account the main fault currents characteristics of the disturbance, such as: low levels of overcurrent, asymmetry between the half-cycles, nonlinearity, buildup, shoulder, and intermittence. The model is based on actual HIF oscillographic data obtained in field tests. Simulations were performed in ATP software and the model was implemented by using MODELS. At the end, it was obtained a model that takes into account the type of contact surface, and simulates a larger number of features than the evaluated models. With a specific model for each type of surface, it was created a database composed of records with IEEE COMTRADE standard. This pattern is used for most digital fault recorders (DFRs), qualimeters, and relays of the electrical system, allowing, in this way, actual data to be inserted to the simulated database without needing any kind of format conversion.