Evaluation of Torsional Efforts on Thermal Machines Shaft with Gas Turbine resulting of Automatic Reclosing

Authors: Alvaro J. P. Ramos, Wellington S. Mota, Yendys S. Dantas

Abstract:

This paper analyses the torsional efforts in gas turbine-generator shafts caused by high speed automatic reclosing of transmission lines. This issue is especially important for cases of three phase short circuit and unsuccessful reclosure of lines in the vicinity of the thermal plant. The analysis was carried out for the thermal plant TERMOPERNAMBUCO located on Northeast region of Brazil. It is shown that stress level caused by lines unsuccessful reclosing can be several times higher than terminal three-phase short circuit. Simulations were carried out with detailed shaft torsional model provided by machine manufacturer and with the “Alternative Transient Program – ATP" program [1]. Unsuccessful three phase reclosing for selected lines in the area closed to the plant indicated most critical cases. Also, reclosing first the terminal next to the gas turbine gererator will lead also to the most critical condition. Considering that the values of transient torques are very sensible to the instant of reclosing, simulation of unsuccessful reclosing with statistics ATP switch were carried out for determination of most critical transient torques for each section of the generator turbine shaft.

Keywords: Torsional Efforts, Thermal Machine, GasTurbine, Automatic Reclosing.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1330003

References:

[1] Alternative Transients Program Program Latin American EMTP Users Group (CLAUE) Furnas Centrais Eletricas S.A Rio de Janeiro BRAZIL
[2] M. C. Hall and D. A. Hodges, "Experience with 500 kV sub synchronous resonance and resulting turbine generator shaft damage at Mohave generation Station," in IEEE Publication 76 CH1066-PWR. New York IEEE Press, 1976, pp. 22-29.
[3] ANSI C50.13-1989, American National Standard for Rotating Electrical Machinery - Cylindrical-Rotor Synchronous Generators.
[4] C. E. J. Bowler, F. G. Brown, D. N. Walker, "Evaluation of the Effect of Power Circuit Breaker Reclosing Practices on Turbine-Generator Shafts", IEEE, TRANS on PAS, Vol. PAS-99, No 5, Sept/Oct. 1980.
[5] J. M. Undrill, L. H. Hannett, "Turbine-Generator Impact Torque in Routine and Fault Operations", Paper and discussions .IEEE, TRANS on PAS, Vol. PAS-98, N0 2, March/April 1979