Influences of Electromagnetic Interferences on Two-Terminal Impedance-Based Fault Location Methods
Faults during transmission line operations are prone to occur, which reinforces the need for protection instruments to ensure the safety of facilities involved and, in case of power outages, to restore the energy supply in the least amount of time as possible. In this context, two terminal impedance-based fault locators are widely used in real installations, since they overcome limitations of single-terminal approaches. In this paper, a study is carried out to evaluate the performance of four classical fault location methods in a transmission system subjected to electromagnetic interferences (EMI). An overhead power line with 334 km is exposed to a hypothetical case of electromagnetic influeence due to inductive coupling with a 28" underground pipeline. The system is modeled using the well-known Alternative Transients Program (ATP) and phase-to-ground faults are simulated, varying fault resistances and locations, in order to obtain a parametric response. Results show that fault location methods based on series impedances, propagation constants and characteristic impedances underperform in situations which the EMI are neglected, presenting errors as large as 60 km. However, methods that do not rely on line parameters show significantly improved accuracy and great robustness with respectto external EMI, presenting fault location estimation errors of only 5%.