Transformer and load modeling in short circuit analysis for distribution systems

Accuracy of short circuit analysis depends on the modeling of transformers and loads. This paper addresses implementation of various transformer and load models in a short-circuit analysis for three-phase unbalanced distribution systems. Detailed transformer models are derived and incorporated into a production grade short circuit program with three different load models. Our studies show that different transformer connections, load models, and loading conditions may have significant impact on post-fault currents and voltages. Some test results on PG&E distribution feeders are presented.