Fault Protection Method for Low-Current Grounding Systems in Active Distribution Networks Based on an Improved Clustering Algorithm

With the increasing global focus on carbon neutrality and the development of renewable energy, a large number of distributed generation units have been integrated into the distribution network to enhance sustainability and reduce carbon emissions. As a result, fault signals often exhibit high-frequency, nonlinear, and weak characteristics, rendering traditional low-current grounding fault line selection methods ineffective. In this paper, by analyzing the differences between the transient zero-sequence currents of low-current grounding faults in active distribution networks, a fault protection method for low-current grounding systems based on an improved clustering algorithm with optimized initial cluster center selection is proposed. The proposed method involves filtering the transient zero-sequence currents, characterizing their phase differences using the cosine distance between each pair of zero-sequence currents, and performing clustering analysis with an improved k-means algorithm. By defining a range for the number of clusters k and determining the optimal value based on the within-cluster sum of squares (WCSS), the fault line can be accurately identified. Simulation results demonstrate that the method is applicable to both conventional low-current systems and low-current systems in active distribution networks, offering good practicality and anti-interference performance.