Operational impedances of turbogenerators with solid rotors

It has long been known that the performance of a turbogenerator differs in certain respects from that predicted by the idealised theory based on Park's equations. The reason is that the damping effects of eddy currents in the solid rotor are not correctly represented by damper coils acting on the two axes. The theory presented in the paper allows for the eddy currents in the determination of the direct- and quadrature-axis operational impedances Xd(p) and Xq(p) They are calculated as frequency-response functions Xd(j?) and Xq(j?) by considering sinusoidally varying fluxes on one or the other axis in the machine at standstill. Two alternatives are considered: one when the flux reverses and the other when there are only flux changes of limited magnitude. The impedance values are used to calculate the characteristics during asynchronous operation and the current after a 3-phase short circuit. Two large machines and one model machine were tested and showed good agreement with the theory. A new method is suggested for determining the value of damping torque for use in a stability study.

[1]  D. B. Mehta,et al.  Transient torque and load angle of a synchronous generator following several types of system disturbance , 1960 .

[2]  P. D. Agarwal.  Eddy-current losses in solid and laminated iron , 1959, Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics.

[3]  H. M. McConnell,et al.  Eddy-current phenomena in ferromagnetic materials , 1954, Electrical Engineering.

[4]  B. J. Chalmers.  Asynchronous performance characteristics of turbo-generators , 1962 .

[5]  R. A. Phillips,et al.  Effect of a Modern Amplidyne Voltage Regulator on Underexcited Operation of Large Turbine Generators [includes discussion] , 1952, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[6]  B. Adkins,et al.  The Application of the Frequency-Response Method to Electrical Machines , 1956 .

[7]  W. J. Gibbs.  Induction and synchronous motors with unlaminated rotors , 1948 .

[8]  C. Concordia,et al.  Synchronous machine with solid cylindrical rotor , 1937, Electrical Engineering.

[9]  C. Concordia.  Synchronous Machine with Solid Cylindrical Rotor - Part II , 1959, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[10]  R. H. Park,et al.  Two-reaction theory of synchronous machines-II , 1933, Transactions of the American Institute of Electrical Engineers.

[11]  Bernard Adkins,et al.  The general theory of electrical machines , 1957 .

[12]  R. H. Park.  Two Reaction Theory of Synchronous Machines , 1929 .