Investigation of Internal Fault Modeling of Powerformer Part II: Model Performance

This paper applies techniques for analyzing internal phase and ground faults in the stator windings of powerformer. A variety of internal fault conditions are considered. Simulation results showing the fault currents, during a single phase to ground fault, a two phase to ground fault and a phase to phase fault, are presented, along with comprehensive data of a 75 MVA and 150 kV powerformer. The simulations were compared with experimental results for phase to phase fault in the stator windings of a 15 kW synchronous test generator as a single machine with no load and neutral grounding with a resistor.