Detection and estimation of voltage disturbances using Wavelet Transforms

The power quality is of utmost concern to the electric power suppliers, equipment manufacturers and the users of various electrical and electronic equipments. The various types of voltage disturbances reported in the LT power supply are voltage sag, voltage swell, voltage outage and transients. They may be multi-cycle events like voltage sag and voltage swell or sub cycle events like transients. There are various methods available to detect, estimate and classify the voltage disturbances. Wavelets are one such mathematical method. The power signal of 50Hz frequency and 230V rms along with the voltage disturbances are simulated and discrete wavelet transforms are obtained. The coefficients obtained from the wavelet transform are used to estimate and classify the voltage disturbances. This work has been implemented in Matlab. The results obtained are accurate enough to detect and classify the various voltage disturbances.