Gaspard Lugrin

An Efficient Method Based on the Electromagnetic Time Reversal to Locate Faults in Power Networks

This paper presents a new method based on the electromagnetic time-reversal (EMTR) theory for locating faults in power networks. The applicability of the EMTR technique to locate faults is first discussed. Using the classical transmission-line equations in the frequency domain, analytical expressions are derived to infer the location of the fault. The accuracy of the proposed method is then discussed in relation to the number of observation points adopted to record the fault-originated electromagnetic transients. Then, this paper illustrates the extension of the proposed method to the time domain. The experimental validation of the proposed method is presented by making reference to a reduced-scale coaxial cable system where real faults are hardware-emulated. Finally, the application of the proposed EMTR-based fault-location method to Electromagnetic Transients Program-simulated cases is presented. The simulated test cases are: a mixed overhead/coaxial cable transmission system and the IEEE 34-bus distribution test feeder. Compared to other transient-based fault-location techniques, the proposed method presents a number of advantages, namely, its straightforward applicability to inhomogeneous media (mixed overhead and coaxial power cable lines), the use of a single observation (measurement) point, and robustness against fault type and fault impedance.

On the Location of Lightning Discharges Using Time Reversal of Electromagnetic Fields

In this paper, we discuss the use of the electromagnetic time reversal (EMTR) method to locate lightning strikes. After a brief description of the EMTR and its application to lightning location, we mathematically demonstrate that the time-of-arrival method can be seen as a subset of EMTR. We propose three different models of backpropagation to address the issue of EMTR not being invariant for lossy media. Two sets of simulations are carried out to evaluate the accuracy of the proposed methods. The first set of simulations is performed using numerically generated fields and the proposed algorithm is shown to give very good results even if the soil is not perfectly conducting. In particular, we show that considering a model in which losses are inverted in the back propagation yields theoretically exact results for the source location. We show also that a lack of access to the complete recorded waveforms may lead to higher location errors, even though the computed errors are found to be within the range of performance of current lightning location systems (LLS). A second set of simulations is performed using the sensor data reported by the Austrian LLS. The locations obtained by way of the proposed EMTR method using only the available sensor data (amplitude, arrival time, and time-to-peak), are observed to be within a few kilometers of the locations supplied by the LLS.

On the use of electromagnetic time reversal to locate faults in series-compensated transmission lines

The paper focuses on the extension to series-compensated multiconductor transmission lines of a new fault location method based on the Electromagnetic Time Reversal (EMTR) theory. The applicability of the EMTR theory to locate faults is first summarized. Then, the paper describes the proposed algorithm to locate faults in multiconductor transmission lines using a single observation point at one of the line terminals. The application of the proposed method to series-compensated transmission lines is finally illustrated by numerical simulations obtained using the EMTP-RV simulation environment where electromagnetic fault-transients are reproduced with reference to a realistic series-compensated overhead transmission line. The resulting fault location accuracy is quantified and analyzed with reference to different fault types.

A new method to locate faults in power networks based on Electromagnetic Time Reversal

The paper presents a new method based on the Electromagnetic Time-Reversal (EMTR) for locating faults in power systems. The applicability of the EMTR to electromagnetic transients associated with traveling waves in transmission lines originated by the fault is theoretically demonstrated. A new fault location technique is then proposed and illustrated for a simple case of a single-conductor transmission line, for which the performance of the proposed technique in terms of location accuracy is discussed. The use of the EMTR technique appears to be particularly promising for locating faults in passive and active electrical distribution networks in view of their radial structure.

High-Frequency Electromagnetic Coupling to Multiconductor Transmission Lines of Finite Length

This paper presents a theory and an efficient solution approach for the problem of electromagnetic field coupling to a long multiconductor line with arbitrary terminations. The theory is applicable for a high-frequency plane wave electromagnetic field excitation, when the transmission line approximation conditions are no longer satisfied.

Assessment of the Influence of Losses on the Performance of the Electromagnetic Time Reversal Fault Location Method

Electromagnetic time reversal (EMTR) has been shown to be an efficient method for locating faults in ac and dc power grids. In the available literature, the back-propagation medium has been considered to have identical losses as the direct-time medium. However, the telegraphers equations describing the traveling wave propagation are time-reversal invariant if and only if inverted losses are considered in the back-propagation phase. This paper presents an analysis of the impact of losses on the performance of the EMTR-based fault location method for power networks. In this respect, three back-propagation models are proposed, analyzed, and compared. It is shown that a lossy back-propagation model, for which the wave equations are not rigorously time-reversal invariant, results in accurate fault locations. Finally, an EMTR fault location system based on the lossy back-propagation model and a fast electromagnetic transient simulation platform is developed and its performances validated.

High-frequency electromagnetic field coupling to a long finite line with vertical risers

In this paper, we consider high-frequency electromagnetic plane wave coupling to a long finite line with vertical risers above a perfectly conducting ground, when the classical Transmission Line (TL) approximation is not applicable. We derive analytical expression for the induced current in the central part of the line, using the so-called asymptotic approach. The application of the asymptotic approach requires the knowledge of reflection and scattering coefficients for current waves in semi-infinite lines. To obtain these coefficients, we have used perturbation theory for the solution of Mixed Potential Integral Equation (MPIE). The obtained results are in very good agreement with numerical simulations.

Assessment of the influence of losses on the performance of the electromagnetic time reversal fault location method

Electromagnetic time reversal (EMTR) has been shown to be an efficient method for locating faults in AC and DC power grids. In the available literature, the back-propagation medium has been considered to have identical losses as the direct-time medium. However, the telegraphers equations describing the travelling wave propagation are time-reversal invariant if and only if inverted losses are considered in the back propagation phase. This paper presents an analysis of the impact of losses on the performance of the EMTR-based fault location method for power networks. In this respect, three back-propagation models are proposed, analyzed and compared. It is shown that a lossy back-propagation model, for which the wave equations are not rigorously time-reversal invariant, results in accurate fault locations. Finally, an EMTR fault location system based on the lossy back-propagation model and a fast electromagnetic transient simulation platform is developed and its performances validated.

Electromagnetic time reversal applied to fault detection: The issue of losses

Electromagnetic time reversal (EMTR) has recently been applied to the problem of fault location in AC and DC power grids. In this paper, we present an analysis of the effect of losses on the application of EMTR to locate faults. Three models for the back propagation are proposed and discussed. We show that a back-propagation model in which the losses are included results in a perfect estimation of the fault location, even though in this case the telegraphers equations are not strictly time-reversal invariant.

Corrections to “Study of the Propagation of Common Mode IEMI Signals Through Concrete Walls”

Presents corrections to the paper, “Study of the propagation of common mode IEMI signals through concrete walls,” (Mora, N., et al), IEEE Trans. Electromagn. Compat., vol. 60, no. 2, pp. 385–393, Apr. 2018.