GB979838A - Improvements in and relating to the control of parallel connected synchronous machines - Google Patents

Abstract

979, 838. Automatic load sharing systems. LLOYD DYNAMOWERKE G.m.b.H. May 19, 1961, No. 18398/61. Heading G3R. A system for automatically maintaining the division of reactive load between a plurality of alternating current generators 10,10' by controlling the field excitation of the machines comprises a resistor 24 in the field circuit of each generator, the resistors 24 being connected in a series circuit which includes control windings 22 on a saturable reactor 19 associated with each generator the arrangement being such that if one machine tends to take too much load, the volt drop across the associated resistor 24 increases thereby causing a circulating current to flow in the series circuit including the control windings 22 which alters the impedances of the saturable reactors 19 to alter the current flowing in the windings 17 of the transformers 13 so to alter the exciting current flowing in the field windings 11 to restore the division of the reactive load. The voltage output of the generators is controlled by voltage regulators 23 and windings 21 on the saturable reactors 19. Other embodiments show the control arrangement dependent on armature current, the control circuit isolated from the field circuit by a pulse transformer, the control circuit modified by the addition of a signal proportional to terminal voltage of the generators and in which only one inter-connecting bus-bar 25 is used.