Transmission lines are usually suspended from steel towers and provided with one or more earth wires. Therefore the earth fault resistance during flash over on the isolators is only few ohm. In the case of rare arc faults, at mid-span, or during flash over to trees, very high impedance faults may result. Depending on the setting of the zones in R-direction, a maximum of some tens of ohms can be...

Symmetrical nature of mean of electrical signals during normal operating conditions is used in the fault detection task for dependable, robust, and simple fault detector implementation is presented in this work. Every fourth cycle of the instantaneous current signal, the mean is computed and carried into the next cycle to discover nonlinearities in the signal. A fault detection task is complete...

In this paper, precise fault location in electrical traction network systems is discussed in the high-frequency domain. Based on the analysis of the equivalent impedance at the measurement terminal, the relationship between the fault distance and the frequency spectrum extreme points of the system impedance are derived. The exact fault location can be obtained from the relationship curves accor...

An intelligent strategy for the protection of AC microgrids is presented in this paper. This method was halving to an initial signal processing step and a machine learning-based forecasting step. The initial stage investigates currents and voltages with a window-based approach based on the dynamic decomposition method (DDM) and then involves the norms of the signals to the resultant DDM data. T...

High impedance faults (HIFs) are difficult to be detected or classified by overcurrent or distance relays. This paper presents a scheme for high impedance fault detection and classification in extra high voltage transmission line. The scheme recognizes the distortion of the current waveforms caused by the arcs usually associated with HIF using a discrete wavelet transform (DWT) based pattern re...

Original scientific paper This paper presents a set of rules for an intelligent algorithm of high impedance fault detection by observing the phase to ground voltage, phase to phase current and harmonics of fault current. Several techniques to detect high impedance faults already exist for example current injection in the neutral, superposing voltage signals, harmonic analysis, neural networks. ...

The ability to detect High Impedance (HiZ) faults has been a topic of research and development for over 30 years. About seven years ago, products began to appear on the market that could securely perform this function. Over this time period, several hundred HiZ detection devices have been placed in service and have performed to expectations. This paper reviews the operating principle of HiZ fau...