Simplified three-phase lateral and feeder models for fast distribution system calculations

This paper introduces three simplified three-phase lateral models for fast distribution system calculations. The models can also be applied to model a feeder with short laterals, whose impedances are negligible. These models are formulated using three lumped individual phase loads to represent single-phase, three-phase unbalanced, and nonuniformly distributed loads along a lateral or feeder. Proposed voltage-drop and line-loss models are developed to accurately simulate the total series voltage drop at the end and the total copper loss of a given lateral, respectively. A hybrid model is then developed to simulate both voltage drop and line loss accurately. All of the proposed models are used to represent the unbalance features of a physical distribution system in which various transformer connections are presented. The proposed models are applied to a physical feeder of Taiwan Power Company (Taipower). The simulation results show that it is possible to simplify complicated laterals or 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 lateral or feeder. (C) 1996 Elsevier Science S.A.