Representation of induction motor loads

IN MOST POWER SYSTEM transient stability studies, the system loads are represented by shunt impedances. Commonly, the shunt impedances are treated as static impedances. This method is especially well adapted for hand calculation and for a-c network analyzer studies. It is, of course, appreciated that all loads do not behave as static impedances and methods have been developed for taking into account, more correctly, the proper variation of real and reactive power with system voltage and frequency changes. These methods have been used, where justified, in some a-c network analyzer transient stability studies.