Abstract :
The difficulties and complication associated with the transmission of large blocks of electric power over considerable distances have led, during recent years, to a growing interest in the possible application of direct current at high voltage for this purpose. In spite of the fact that alternating current lends itself readily to generation and potential transformation in bulk, it cannot compete with direct current where transmission on a similar scale is concerned. For this reason direct current can, under certain circumstances, form an economic link between the source of energy supply and the consumer. The paper presents a broad survey of the basic problems involved in generating, transmitting, and transforming electrical energy in the form of super-tension direct current as they appear at the present time, without attempting to add new matter to a subject which is of necessity highly specialized and the province of the transmission engineer. After a brief historical review of the subject has been given in the Introduction, the manifold advantages of high-voltage direct current as a means of power transmission are discussed and the factors limiting its direct generation are investigated. Of the several methods available for converting alternating current to direct current at high voltages, relatively few are at once technically and commercially feasible. A general account is given of those current-converting systems which seem to offer the most promising solution of the transmission problem. The general trend of opinion in favour of the super-tension direct-curent system as reflected in modern transmission projects is explained, and an outline is given of three such schemes of major importance which have been put forward during the last few years. Finally, the paper indicates the course of a rational future development and suggests how the super-tension direct current system of power transmission might with advantage be introduced and further technical data obtain- ed. References to recent literature dealing with the transmission problem are given in a Bibliography.
