A MODAL APPROACH TO THE TRANSIENT ANALYSIS OF SYNCHRONOUS MACHINES

ABSTRACT

A novel method for calculating the transient currents, flux linkages and electromagnetic torque of a synchronous machine following a sudden voltage disturbance is presented. The solution is obtained for a sudden change from an arbitrary balanced to an arbitrary unbalanced voltage condition. Since minimum constraints are placed on the disturbance, many typical types of transients such as three-phase and line-to-line short-circuit faults can be accommodated. Complete solutions for all machine currents are obtained as explicit functions of time. Any number of rotor circuits can be included and full allowance is inherently made for coupling between all stator and rotor circuits. Constant speed is assumed but no additional approximations are made other than those implicit in the derivation of Park's Equations. The technique incorporates the state space concept of modal analysis in its implementation. Closed form solutions obtained by the modal theory are compared with standard solution techniques