A d-q Axis Process Model for Simulation of Transients in Magnetically Saturated Synchronous Machines

L. Lupşa-Tătaru and D. Ilea (Romania)


Power system transients, modelling and simulation, process model, synchronous machine.


Starting from the synchronous machine d-q axis model extended for unsteady operation, a general process model (GPM) is developed by considering the magnetic saturation phenomenon through the inductance-currents type of non-linearities. Following the selection of flux linkages as state variables, the equations defining the GPM do not contain quantities generated by the time related differentiation of the magnetizing or leakage inductances. Consequently, the number of inductances is preserved. The equation of mechanical motion is inserted and, thus, the driving torque, fictitious stator and excitation voltages remain input variables. The resulted GPM is described by a non-linear system of eight differential equations in the canonical form. Therefore, the GPM is prepared to be lightly integrated into computer software platforms of any complexity. The paper illustrates the employment of the GPM in order to simulate the typical transient of sudden three-phase short circuit at the terminals of a synchronous generator endowed with damping cage and salient poles.

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