Abstract :
To improve efficiency and alleviate certain limitations in large generators, two separate stator windings have been suggested. The behavior of an alternator with two 3-phase stator windings displaced by an angle e;, is analyzed by means of an orthogonal transformation of the a, b, c; A, B, C; and fd variables into a new set: dl, ql, 01; d2, q2, 02; and fd. For balanced operating conditions the differential equations with the new variables have time-indenendent coefficients. Thus a phasor diagram can be drawn using self and mutual reactances Xd, Xqv X12d and X12q, determined from flux linkages. The latter are based on flux plots obtained bysolving the quasi-Poissoniandifferentialequation. The characteristic parameters for a specific operating condition are calculated for a 1200 MVA, 24 kV, 60 Hz, two-pole turbogenerator, and test data are presented covering single circuit operation on a 2-circuit generator with 600 belts connected as an alternate pole and alternate belt type double winding machine.
