SIMULATION OF GENERATOR TRANSIENTS WITH STATOR PHASE WINDING ASYMMETRY AND MAGNETIC SYSTEM SATURATION

Abstract

The article deals with the transients of a synchronous machine with allowance for its magnetic system saturation. A method of numerical simulation of synchronous machine transients is proposed with the possibility of taking into account the asymmetry of stator winding and magnetic system. The asymmetry arises if the synchronous machine is damaged, in particular in the case when inter-turn short circuits occur in the stator winding. The study uses a direct solution of the differential equations of emf equilibrium and voltage drops in windings in phase coordinates together with the rotor motion equation. In this case, the contour of each phase winding of the stator is described by a separate equation. Different phase parameters can be taken into account as well. The mathematical model of a synchronous generator operating into an active-inductive load is implemented in the software package MATLAB. The model takes into account one of the possible types of asymmetry: it is an unequal number of turns in phase windings. This enables the modeling of interturn short circuits without allowance for the occurance of additional short-circuits. The effect of damper windings on the transient caused by a sudden short circuit in the system is accounted. It is compared with the damper winding-free model. The simulation results are analyzed taking into account the saturation of the machine magnetic system. The obtained results allowed to draw a conclusion about the adequacy of the implemented model.