Internal Faults in Synchronous Machines: Modelling Internal Impedances for Concentric and Diamond Windings

K. Johnsen (Denmark)


Synchronous machines, machine network model, internal faults, internal impedance modeling, concentric windings, diamond windings


This paper is concerned with a proposal for the actual modelling of the internal partitioned impedances of an in ternally faulted synchronous machine with either concen tric or diamond phase windings. Taking a solenoidal ap proach, the resulting modelling becomes rather simple, in terms of algebraic expressions, applying only a simple, but apparently sufficient, electromagnetic relation to the models of the impedances. As shown in the paper, a sole noidal approach for modelling both the concentric and the diamond wound machines fulfils the boundary conditions given in the network model to be used for evaluating the internal fault consequences. The described model is supposed to be used together with the network models presented in a previous paper in in ternal faults in synchronous machines, dependent on the situation that is treated. Calculated examples using this approach are given, showing the relation between the rms magnitude of the initial short-circuit current during an in ternal 1-phase-to-earth fault dependent on the relative po sition along the phase-winding of the armature of the syn chronous machine. These are compared to the results of actual experiments, which are conducted on appropriate machine.

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