Stability of large power systems

The paper deals with the stability, voltage control, and power limits of electric- power systems and machines¿more particularly, large alternating-current systems. The subject is dealt with in the following sequence :¿ Definition of stability. Stability and power limits of simple circuits. Larger power lines. Artificial stability of power lines. Natural stability and power limits of alternators and synchronous machines. Short-circuits and transient stability of alternators. Internal reserve of excitation of synchronous machines. Artificial stability of alternators. Stability of exciters. Types of electric power supply systems. Feeders and transmission lines and their voltage control. The conclusions reached are that synchronous machines can be made sufficiently stable for all the usual purposes of power supply, and that the power limit and voltage regulation of transmission circuits depend principally on their series reactance.