Synchronous Machine Modeling for Low-Frequency Harmonic Studies

Power quality, and harmonics in particular, is a major issue in any isolated power system due to extensive use of non-linear power electronic devices. The harmonic problem in an isolated system is even more magnified because of the absence of an external grid, which is a basic characteristic of all isolated systems (like that of a ship). Harmonic studies are, therefore, conducted on a fairly regular basis to analyze and rectify the problems associated with harmonics. In order to conduct such studies in any electrical system, it is important to accurately model its components. As there is no transmission network or "system equivalent," the generator(s) represents a major portion of an isolated power system. Within this paper, appropriate models of synchronous generators for low-frequency harmonic studies are presented. These models are developed using detailed "dq0" representations of the synchronous machine.