Frequency analysis of high-impedance arcing fault currents on DC trolley systems

An overview is first presented on past research on high-impedance faults on ac and dc distribution systems. Then the theoretic analyses of arc currents are followed. The arcing process is first analyzed as a deterministic process. The non-linear models of the arc are used for the analysis. The analysis facilitates a clear explanation of the enhancement of harmonics of trolley currents under fault conditions. The next step is to model the arc as a stochastic process. Through analysis of this model, the random behavior of high-impedance arcing fault currents becomes clear. This model also makes it possible to explain the reasons for the creation of frequency components in an arcing fault current. Following that is the description of the experimental research on arcing fault currents. It includes the experimental methodology, data analysis, and experimental observations. These experiments have demonstrated that the frequency distribution of arc currents differ from those of the legitimate currents. Finally, an introduction to the two promising implementations of this research is described.