A Digital Computer Program for the Automatic Determination of Dynamic Stability Limits

The ability to calculate the dynamic stability limits of synchronous machines is of increasing importance today as generation and transmission equipment are being applied with higher reactances and correspondingly lower stability margins. This paper describes a digital computer program which enables the rapid computation of dynamic stability limits for a single machine connected to an infinite receiving system through a transmission line. Effects of excitation and prime mover power controls are included making the program a valuable tool for the equipment designer. Typical results illustrate the effect of terminal voltage, transmission line reactance, and machine inertia on the stability limits. The concept of damping ratio as an index to relative stability is discussed and illustrated. Also shown are the effects of neglecting saturation and other second-order effects on the calculation of dynamic stability.