Measurements of Torsional Dynamic Characteristics of The San Juan No. 2 Turbine-Generator

Abstract

The San Juan Generating Station, jointly owned by Public Service Company of New Mexico and Tucson Gas & Electric Company, is located in the northwestern part of New Mexico. Expansion plans for the transmission system include the addition of series capacitors on lines leaving the plant, necessitating a detailed study of potential subsynchronous resonance problems. A field test was performed on the San Juan No. 2 turbine-generator to obtain measured data for use in these studies. The required data included measurements of torsional resonant frequencies below 60 Hz, mode shapes, and damping characteristics. Test procedures and measurement techniques for obtaining these data are described. The results show that the disturbances caused by line switching in transmission systems can be closely calculated. They also show the correlation between calculated and measured torsional frequencies and mode shapes. The damping coefficient for the first torsional mode is shown to be strongly influenced by electrical system parameters as well as machine loading.