Electromagnetic Time-Reversal Fault Location Using Active Pulse Injection
Existing EMTR methods typically adopt passive location schemes that rely on transient signals generated by faults. When faults occur at a low inception angle, the resulting traveling-wave signals are typically weak and suffer from poor detectability. Active pulse injection provides controllable excitation and improves signal identification. The transfer function similarity method achieves high accuracy; its practical application is constrained by the requirement for transient voltage at the fault point. To address these limitations, this paper proposes a fault location method based on active pulse injection and systematically investigates the characteristics of fault voltage in both frequency and time domains. First, the frequency-domain formulation of fault voltage in the reversed-time process is derived, and the applicable scope of the energy metric is evaluated. The waveform features of the reversed-time fault voltage are then analyzed to assess the similarity between the fault voltage and the injected pulse voltage, as well as the applicability of the MCCC metric. An improved IMCCC criterion is developed to quantify the similarity between the fault voltage and the forward-time voltage. Furthermore, a symmetry similarity coefficient (SSC) is defined by leveraging the inherent symmetry property of fault voltage waveforms. The four metrics were validated using reduced-scale experiments and simulation studies. All metrics achieved accurate fault location in simple lines. In complex networks, the energy metric showed significant deviation from the real fault location. The IMCCC and SSC metrics provided higher accuracy than the MCCC metric and maintained reliable fault location for grounding faults up to 300 Ω.