Characteristics of Interconnected Power Systems As Affected by Transformer Ratio Control

Operating characteristics of interconnected systems in which voltage is maintained constant by varying field of the generators is compared with operating characteristics, when, in addition to the control of generator field, transformers equipped with ratio control are employed. The use of transformers with variable ratio introduces a flexibility in operation which permits the division of wattless currents between generating stations independent of voltage held at the generator busses. A comparison is made of the use of synchronous condensers for the purpose of improving regulation as compared with the use of transformers equipped with ratio control. The elementary conditions which govern the current distribution in a loop, L, are determined in terms of impedance characteristics of the net-work. The equipments necessary to control the current distribution and at the same time maintain good regulation in the loop are indicated.