The Theory of Neglecting Stator Transients

For more than four decades it has been thought that neglecting the so-called "ph terms" in Park's equations is equivalent to neglecting the electric transients due to the stator windings of a synchronous machine. Over the years, trial and error results have indicated that a more accurate prediction of synchronous machine performance could be obtained if the Aw(p6) terms in the stator voltage equations were also neglected. This paper provides a theoretical explanation of this experimental observation. In particular, it is established theoretically that in order to neglect the "stator transients" both the p* and Aw terms must be set equal to zero. This is accomplished by proving that the equivalence of neglecting the pq terms in the synchronous reference frame is to neglect the p* and Aw terms in all other reference frames. R-L transmission systems, synchronous and induction machines are considered.