Synchronizing Transients and Synchronizers for Large Machines

Abstract

This paper reports an investigation of the transients accompanying synchronizing operations performed under practical conditions which include some departures from the ideal conditions as to voltage, phase position, and frequency of the incoming machine. A typical long-distance transmission system is selected for the study of the transients arising from the synchronizing of one of several similar units connected to the same sending-end bus. This problem reduces to that of a three-machine stability problem which is carried out with the aid of the a-c network calculator. The body of the paper shows the variations in initial and maximum ``swing'' currents, in voltage, in frequency, and in angular relations which may be produced by synchronizing under unfavorable conditions. The results of this study are then examined from the standpoint of automatic synchronizers and criteria for defining their performances are developed. The latter part of the paper includes a description of a new electronic type of automatic synchronizer. The operating features of this synchronizer, which have been installed on the more recent units of the Boulder Dam installation, are discussed.