Effects of Excitation, Turbine Energy Control, and Transmission on Transient Stability

Transient stability problems become much more severe where the system design criteria is based on "stuck-breaker" fault clearing times, particularly where three-phase faults are used. Such a criterion is difficult and frequently impossible to meet with normal system design. Results of studies exploring the relative effect on transient stability limits of several options available to the system planner, including transmission strength, excitation system response, and early valving, are presented. Early valving appears to offer attractive stability improvement in those cases where such improvement is needed.