Synchronous-machine sudden 3-phase short-circuit. Analysis by norton´s, constant-flux-linkage and thévenin´s theorems

The paper presents a new technique of analysis. Equivalent circuits, which normally omit altogether the asymmetrical and 2nd-harmonic armature-current components, are made to give the complete solution including the said components by applying theorems which are well known for their simplifying effect. In the first alternative, Norton´s theorem is used to replace the 3-phase armature-voltage source by equivalent current sources on the direct and quadrature axes. The appropriate axis loads presented by the rest of the machine are connected to the current sources. Thus, appropriately energised equivalent circuits are obtained which give the complete solution. In the second alternative, the `effective¿ 2-axis armature-voltage source, for short-circuit conditions, is determined by the constant-flux-linkage theorem. Then, by Thévenin´s theorem, the appropriately energised equivalent circuits are obtained which again give the complete solution.