A noise suppression method for improvement of power quality using wavelet transforms

Electric power quality has become an important issue in power systems. This is due to the fact that the usage of power electronic equipment and electronic-based loads, which are sensitive to power quality disturbances, has increased, and thus normal operations in industrial and commercial environments are becoming more vulnerable to the electric power quality disturbances. In order to improve the quality of power, this paper presents a new noise suppression method to remove the noise associated with various types of electric power disturbances using the discrete wavelet transform. Power system disturbances such as those due to voltage sag, voltage swell, outage, waveshape fault-impulse, harmonic distortion, capacitor energisation transients and arc furnace are simulated using the well known Electromagnetic Transients Program (EMTP). The wavelet transform, which has received considerable interest in many other areas such as acoustics, communications, etc., is proposed as a fast and effective means of analysing voltage and current waveforms generated during power system disturbances; this method hinges upon realising a given noise-ridden signal into a number of other signals which represent detailed components of the original signal. The decomposition is performed using multi-resolution signal decomposition techniques. The simulation results clearly demonstrate the superiority and effectiveness of the wavelet transform in both voltage and current signal noise reduction