Sag voltage identification on 30 kV systems affected by electric arc furnace using wavelet transformation method

This paper presents sag voltage identification on 30 kV system with electric arc furnace load. The identification of disturbance using wavelet transformation. The proposed method can precisely identify sags caused by 3 disturbances: single-phase, two-phase, and three-phase short circuits, which occur in internally process of an electric arc furnace (EAF). The identification procedure consists of 3 steps: preparation, wavelet energy calculation, analysis for identification. The types of short circuit are detected from the amount of energy during the EAF operation. The highest energy required indicates a three-phase short circuit; however the lightest is for single-phase short circuit. Simulation results from a typical data show that a sag voltage in 0.55-0.75 pu for 0.201 seconds, containing wavelet energy average 0.434733, is caused by 3 types of short circuit in certain subsequent time.