Blocking of distance relays zone3 under load encroachment conditions using decision tree technique

False tripping of distance relays on load encroachment may lead to cascade tripping and subsequent blackouts. Hence relays should be supervised to avoid tripping on load encroachment. In this paper, an algorithm based on Decision Tree (DT) is proposed for the differentiation of load encroachment from fault. DT is formulated using Transient Stability Margin (TSM) of generator angles as an attribute. The distance relay is supervised with the decision from DT to avoid tripping on load encroachment. Case Studies are presented on IEEE New England 39 bus system using DIgSILENT PowerFactory software. The simulated results proves the effectiveness of the proposed scheme.