Three-phase fuzzy feeder models for fast distribution system calculations

Based on fuzzy set theory, this study introduces three novel three-phase fuzzy feeder models for fast distribution system calculations. These fuzzy models are formulated using three lumped individual phase loads to represent single-phase, three-phase unbalanced, and nonuniformly distributed loads along a feeder. The proposed voltage-drop and line-loss fuzzy models are developed to accurately simulate the total series voltage drop at the end and the total copper loss of a given feeder, respectively. A hybrid fuzzy model is then developed to simulate both voltage drop and line loss accurately. The proposed fuzzy models are applied to a physical feeder. Simulation results show that it is possible to simplify complicated feeders to simple equivalent models in the calculations of voltage profiles and line losses with negligible error, even if there are various transformer connection schemes in the feeder.