A Novel Hypothesis Testing-Based Scheme for Root Cause Classification of Disturbances in Distribution Systems

In power systems, disturbances often result from faults or operational events, making it crucial to accurately identify their sources to prevent system failures and maintain grid stability. Existing research primarily classifies disturbances based on waveform characteristics, such as sags, swells, and transients, without determining their root causes, including incipient faults, constant impedance faults, load switching, and capacitor switching events. This paper proposes a hypothesis testing-based scheme for classifying power distribution disturbances by their root causes, ensuring reliable and interpretable results without extensive datasets. The scheme uses discrete-time voltage and current measurements at substations to develop disturbance models for substation voltages, incorporating disturbance parameters and load impedance. Load impedance is estimated from recent normal cycles, and disturbance parameters are then derived using substation measurements and the estimated load impedance. By substituting these estimated parameters into the corresponding disturbance models, substation voltages for each disturbance type are estimated. The disturbance type is classified by selecting the one that minimizes the normalized mean square error between the estimated and measured substation voltages. The proposed method is evaluated using the IEEE 13-bus test feeder simulated in PSCAD/EMTDC and validated on a two-day real-world power system dataset collected by the IEEE Power & Energy Society Working Group on Power Quality Data Analytics.