Electromagnetic Time Reversal Applied to Fault Location: On the Properties of Back-Injected Signals

Abstract

By using the electromagnetic time reversal (EMTR) theory, the paper studies its properties in order to derive a new fault location method to be used in power networks. It is shown that, in the reversed-time stage, the current signal observed at the true fault location can be clearly distinguished since it appears as a time-delayed copy of the back-injected fault-originated transient signal. Then, based on this similarity property, a fault location method is derived. Finally, the method is numerically validated with reference to a reproducible simulated power network composed of an inhomogeneous multi-conductor transmission-line system.

MT–HVdc Systems Fault Classification and Location Methods Based on Traveling and Non-Traveling Waves—A Comprehensive Review

“…Electromagnetic time reversal (EMTR) method for fault estimation in MT--HVdc offers significant advantages, such as tolerance of low sampling rate, non-requirement of accurate fault arrival time, and superiority compared to transient method for high resistance faults [114][115][116][117][118][119][120][121]. This method is based on reversing the direction of time (t), given as:…”

“…In this method, electric fields are recorded at terminals (VSCs). Recorded electric fields are flipped over time and re-transmission of electric fields is achieved from sensing terminals and reflected back to the sensing terminals are observed [114,117]. Mathematically, electric field ( ) is given as: This method is more sensitive and accurate than non-traveling wave methods based on voltage or current values, only.…”

“…Electromagnetic time reversal (EMTR) based model of high-voltage direct current (HVdc) transmission system.Thus, time reversed electric fields are: of electric fields is accomplished and total reflected field is[117]:…”

Electromagnetic Time Reversal as a Correlation Estimator: Improved Metrics and Design Criteria for Fault Location in Power Grids

“…The same observations apply to L ∞ , which was proposed in previous EMTR works. A previous attempt at using similarity-based metrics for EMTR was also recently discussed in [21], but it was rather based on the search for positions where the transient measured by the probe would be most similar to the signal observed at the test fault position after injecting the TR version of the transient. This approach should not be confused with the one here proposed, since it introduces a further location metric without recognizing that current EMTR metrics already are inaccurate and ineffective correlators.…”

“…This approach should not be confused with the one here proposed, since it introduces a further location metric without recognizing that current EMTR metrics already are inaccurate and ineffective correlators. Indeed, [21] does not acknowledge the fundamental role of the spectrum of the transient signal, which is the main obstacle to make EMTR reliable and efficient.…”