Shapley Additive Explanations for Traveling Wave-based Protection on Distribution Systems

This paper proposes a framework to explain and quantify how a Traveling Wave (TW)-based fault location classifier, a Random Forest, is affected by different TW propagation factors. The classifier’s goal is to determine the faulty Protection Zone. In order to work with a simplified, yet realistic, distribution system, this work considers a use case with different configurations that are obtained by optionally including several common distribution elements such as voltage regulators, capacitor banks, laterals, and extra loads. Simulated faults are decomposed in frequency bands using the Stationary Wavelet Transform, and the classifier is trained with such signals’ energy. SHapley Additive exPlanations (SHAP) are used to identify the most important features, and the effect of different fault configurations is quantified using the Jensen-Shannon Divergence. Results show that distance, the presence of voltage regulators and the fault type are the main factors that affect the classifier’s behavior.