Multifault calculation method for dynamic stability study of electric power systems

For the fault condition in dynamic stability study, balanced faults have mainly been utilized. Recently, however, with the progress of system protective control technologies such as the multiphase reclosing system for a faulted transmission line, the needs for stability software which would be able to calculate simultaneous faults without any restrictions on fault types, total numbers or location, have been increasing. This report presents the newly developed multifault calculation method based on symmetrical components which is able to calculate simultaneous faults without any restrictions on combination of fault types, and total numbers or location. Fault types consist of balanced/ unbalanced ground fault, short-circuit fault, line-out of transmission lines, and short-circuit of series condenser. The proposed method also allows for calculation of faults at an arbitrary location on the line without any topological changes of each symmetrical network even if the faults include line-end faults with ensuring outages. An example was shown to clarify the validity of the proposed method. Moreover, transient stability limits under the various fault conditions also were discussed.