Digital Analysis of Excitation Control for Interconnected Power Systems

Excitation control by stabilizing signal taken from several locations in the system, together with the proper transfer function, has been investigated to satisfy the system stability from an overall performance view point, rather than one machine against an infinite bus. Several stabilizing signals have been tried from which the following signals have been found to have a great affect in increasing the damping: (1) a signal from the change of network voltage and taken from the far end, and (2) a signal from the change in the machine terminal frequency through a compensating network having a transfer function containing three zeros and three poles. The location of such signals greatly effects the system stability, and it is found that the signal taken from the change of frequency at a remote point of the network and applied to the voltage regulator of the machine under consideration has more effect in stabilizing the system. The station working with a leading power factor makes the stability rather critical, and stabilizing such stations greatly improves the system stability.