The direct- and quadrature-axis equivalent circuits of the synchronous machine

THE EQUIVALENT-CIRCUIT method of analysis is a tool of unquestioned competence in the solution of machine and system problems involving a number of simultaneous equations. Its efficacy in obtaining practical results has been demonstrated in many diverse applications. In particular, the complete equivalent circuit of the synchronous machine — complete in the sense that the field-winding circuit and the multiple damper-winding circuits are individually included — is used whenever a detailed knowledge is needed of the operation of all the rotor circuits. Specific examples of its use are in the design of the damper-winding circuits, in problems involving single-phase and asynchronous operation, in the determination of damping and synchronizing torque, and in the determination of the transient and subtransient impedances; these few by no means exhaust the list.