Diagnostics of the Residual Resource of the Shafting System of Turbine Unit

Abstract

The research paper considers issues, which concern the possibility of extending the service life of turbine units, in particular, by the criterion of accumulated damage to their shaft system for the design resource life of a steam turbine. Developed mathematical model of an electric power system with turbine generators, transformers, transmission lines of alternating and direct current, intended for direct reproduction of electromagnetic and mechanical transients, analysis of the damageability of the turbine shaft systems and evaluation of its residual life. When assessing damageability, an approach was used with the application of the deformation criterion for soft and hard loads in the low-cycle fatigue zone and the strength criterion in the high-cycle fatigue zone. The influence of the number of launches and operating time of the steam turbine on the damageability and residual life of the shafting system was investigated. The dependences of the total damageability to the shafting system on the angle of switching on the generator from idling into the network for a different number of starts during the operating time of the turbine were given. While determining the residual life of the shafting system after the expiration of the turbine design resource life, in addition to start-ups, other abnormal modes of operation of the turbo generator during this period were taken into account: short circuits and their disconnection, unsuccessful automatic high-speed reclosing, subsynchronous resonance. The influence of attenuation of electromagnetic transients in the generator and the damping of torsional oscillations on the degree of reduction of the residual life of the shafting system was analyzed.