3-PHASE COGENERATOR AND TRANSFORMER MODELS FOR DISTRIBUTION-SYSTEM ANALYSIS

This paper presents detailed three-phase cogenerator and transformer models for analyzing a large-scale distribution system. The cogenerator model presented here is significant in that it will represent the inherent generator phase imbalance due to distribution system imbalance. The cogenerators can be synchronous or induction and can be on either primary or secondary systems. The transformer models consider the copper and core losses, the winding connection, the phase-shifting between primary and secondary windings, and the off-nominal tapping. An individual phase, as opposed to a balanced three-phase, representation was employed. This approach is oriented toward applications in distribution system operational analysis rather than planning analysis. This difference should be properly emphasized. The misuse of the planning oriented method to analyze the operational behavior of the system will distort the explanation of the calculated results and lead to incorrect conclusions.