Transfer Function of A.C. Machines

Abstract

The concept of transfer function can be easily extended to rotating machines if Laplace transform is applied to generalized vector equations. The solutions are directly available, are rigorous and are very easy to handle. The only restriction imposed is linearity, by virtue of the Laplace transform. Classical concepts like transient and subtransient reactances and time constants can be precisely defined. Two results are of immediate practical value: during disturbances the ac current components will deviate from 60 Hz, even if the rotors of synchronous machines maintain their speed, affecting the operation of frequency relays; an inexpensive analog model can be developed some 100,000 times faster than the 60 Hz real time frame.