Internal Faults in Synchronous Machines: Network Model for Internal Fault Analysis

K. Johnsen (Denmark)


Synchronous machines, machine network model, internal faults, Thevenins principle, Kronian organized mesh method.


This paper treats a network model for calculating short circuit currents from internal shunt short-circuits in syn chronous machines, and describes an operationally dual method to the method previously employed to analyze in ternal shunt faults in synchronous machines. The model for internal shunt short-circuits is derived by theoretical means under the assumption that the machine considered is an ideal synchronous machine, by initially neglecting all resistances in the machine. Next, internal series faults in synchronous machines are dealt with by applying the organized cut-set method by Gabriel Kron. One or several simultaneous faults can be treated by the same matrix equation. The network model is to be used in conjunction with a model for the internal impedances in faulted ma chines. On the basis that the machine acts as an ideal syn chronous machine, it can be represented in symmetrical components. The model is analytically derived using only those data that manufactures normally provide. The calcu lations are done, assuming that the respective internal im pedances can be calculated, by means of applying a rela tively simple network model for the faulted machine. This approach uses Thevenins principle for calculating short circuits.

Important Links:

Go Back