An Intelligent-Based Technique for Locating Switched Capacitors in the Distribution Systems Using High Frequency Transients

With the increase of the usage of sensitive loads such as adjustable speed drives, utilities and customers paid more attention to power quality (PQ) problems. Switching of shunt capacitors is one of the major power quality problems that generates wide band of voltage and current transients which harmfully affect these types of sensitive loads. This paper presents an accurate technique for locating switched capacitors in the industrial distribution systems. The technique relays on combining the three phase currents at the customer side to construct one modal current signal, and then the discrete wavelet transform (DWT) is used to capture the high frequency current transients contained in this modal signal. The energy contained in the high frequency current transients and the transient duration, converted into number of samples, for two DWT decomposition levels are used to feed a decision tree (DT) classifier to classify the switched capacitor. The simulations are performed using PSCAD/EMTDC and the results are then interfaced to See5.00, where the DT where constructed and trained. It is found, based on simulation, that the technique gives reliable results for locating switched capacitors.