Analysis of Steady-State Stability Using Synchronizing Torque

Abstract

The authors have named dT_e/dδ synchronizing torque and have shown a step-out discriminant by using this, where T_e is the torque generated by a synchronous generator. Next, we have introduced a measurement method of the synchronizing torque based on the measurement of T_m-δ characteristics, where T_m is the torque generated by a prime mover. By using this method, we have proved that a step-out occurs where synchronizing torque has become zero. We have measured the magnitude of the inverse frequency transfer function in 0.1Hz, that is the synchronizing torque considering the hysteresis of T_m-δ characteristics. Next, we have deduced the synchronizing torque formula considering the nonlinear magnetic phenomena. Differential constants x_d*, x_q* are necessary to obtain the synchronizing torque calculated values related to the synchronizing torque measurement values based on the measurement of T_m-δ characteristics. Incremental constants _??__d, _??__q, are necessary to obtain the calculated values related to the synchronizing torque measurement values based on the inverse vector locus measurement method. Both constants agree in the ordinary region, so both calculated values agree. As _??__q is less than x_q* in the neighborhood of the steadystate stability limit, the calculated value based on the incremental constants is greater than the calculated value based on the diffarential constants. And, the calculated values almost have agreed with the measured values. Finally, we have predicted a steady-state stability limit by the synchronizing torque calculated values using diffarential constants, which limit substantially has agreed with actual limit.