Short-circuit analysis of an isolated generator and comparative study of IEC, ANSI and dynamic simulation

The accurate evaluation of short-circuit currents is significant for the estimation of the maximum thermal and mechanical stress in electrical equipment and for the protection coordination of power systems. The IEC-60909 standard is widely used for the calculation of maximum and minimum short-circuit currents. The calculation according to the ANSI standard is also a reliable tool for the proper selection of circuit breakers. Symmetrical and asymmetrical fault currents in a typical topology of an isolated synchronous generator feeding local loads, fault current results are calculated using IEC-60909 and ANSI standards and are compared to the corresponding obtained by the dynamic simulation using ATP/EMTP. The influence of different network parameters as well as of some simplifying assumptions on generator modeling in both standards is systematically investigated and differences between the static and the dynamic analysis are examined.