Finite-Element Simulation of Turbine-Generator Terminal Faults and Application to Machine Parameter Prediction

A finite-element, time-stepping technique is described for simulation of balanced and unbalanced terminal faults on a turbine-generator. Magnetic saturation, induced currents in the rotor body, wedges and field winding, and the relative motion between the rotor and stator windings, are modelled. Calculated values of induced field winding and stator phase currents, following a 0.5 p.u. sudden shortcircuit on a 660 MW machine, are shown to be in close agreement with test results. The numerical model has been used to simulate terminal short-circuits at different pre-fault voltage levels so that the effect of stator saturation can be observed.