Analysis of Transient Disturbances in Distribution Systems: A Hybrid Approach

Built-in event diagnosis and assessment modules are the key to the power quality (PQ) monitoring systems. Discrete wavelet transform (DWT) has been used recently by many researchers for detection and analysis of the of PQ disturbances. Despite the excellent time-frequency localization property, DWT based event detectors can not adapt itself to the dynamic changes in the load configuration because of its fixed filter coefficients and, hence, generates repeated detection and processing of the same steady state disturbance. An adaptive filter on the other hand adapts its filter coefficients continuously with changing monitored signal. Therefore, an adaptive filtering and DWT based hybrid system has been proposed in this paper for the detection and analysis of transient disturbances. Adaptive filter based monitoring avoids the detection of the same study event repeatedly. Extensive tests conducted on the data obtained from a practical distribution system confirm the effectiveness of the proposed approach in automatic detection and diagnosis of transient PQ violations.