Low-Frequency Electromagnetic Transients Characterization Using Stockwell Transform
This paper investigates characterization of low-frequency electromagnetic transients occurring in power networks with the Stockwell transform (S-transform). Three characteristic cases of real network events are considered. The experiments are conducted in the 35 kV network, and voltage and current signals are recorded. The S-transform is applied to analyze voltage and current signals recorded during earth fault, ferroresonance and transformer inrush. The obtained results demonstrate that application of the S-transform enables identifying and distinguishing different low-frequency electromagnetic transients. The S-transform scalograms and energy spectrum diagrams provide necessary information to enable more efficient protection measures against problems in the network caused by different low-frequency electromagnetic transient phenomena.