Improving the reliability of 6-35 kV networks by using STA/LTA method

Quick and accurate detection of single phase to earth faults (SPEF) in electric grids is a relevant problem. However, the existing methods and tools are not always capable of ensuring sufficient quality of such detection, which is why developing SPEF detection tools and methods is an ongoing effort. This paper proposes an STA/LTA-based SPEF detection method; the STA/LTA method is widely used for detecting seismic activity. The paper describes this method and presents an algorithm of using it to detect SPEF in distribution grids. An SPEF-detection VBA application has been developed based on this algorithm. To test the method, a cable-grid computer model was made in PSCAD, matching a real-world urban grid segment. The model-generated SPEF voltage and current oscillograms were processed by the developed application. Simulation and computation results analysis can identify STA/LTA trigger thresholds for reliable SPEF detection. Trigger boundaries are defined in relative units, making the method adaptive to changes in grid topology. Therefore, testing the STA/LTA method by means of a PSCAD model proves its efficiency and great potential for SPEF detection.