SIMULATION OF A SYNCHRONOUS GENERATOR CONNECTED VIA A DELTA-STAR TRANSFORMER

A mathematical model of a 3-phase synchronous machine, connected to the infinite bus through a delta-star transformer and a transmission line, is given. Symmetric and asymmetric faults on the low-voltage side and on the high-voltage side of the transformer are analyzed by using 3-phase variables. Since the simulation is in terms of the direct-phase quantities, the digital-program solution can very easily simulate simultaneous fault conditions as well as sequential faults on either side of the power transformer. By applying proper constraint conditions, the model can be readily used to include symmetric and asymmetric faults for an unloaded alternator, and power-frequency transients following the closure of the generator circuit breaker.