Torsional vibration fatigue life loss estimation method and system for generator unit shaft system-vanes

Abstract

The invention belongs to the technical field of torsional vibration safety estimation of a turbo generator unit, and particularly relates to a torsional vibration fatigue life loss estimation method and system for generator unit shaft system-vanes. A generator unit shaft system-vane coupling vibration model is built according to the actual structure of generator unit shaft system-vanes; the electromagnetic torque of a generator and the steam moment of a turbine are calculated by monitoring the three-phase current, voltage and rotation speed of the generator; vibration response, relative displacement between mass blocks of the model, the dangerous section torsional stress response of a shaft system and the dangerous point stress response of vanes are calculated; the fatigue life loss of a rotor and a vane dangerous point is calculated according to a torsion S-N curve of rotor materials and an S-N curve of vane materials. The torsional vibration fatigue life loss estimation method and system for the generator unit shaft system-vanes builds a vane displacement-stress relationship, can accurately calculate the stress of the vane dangerous point through the peripheral displacement of the vanes, and can accurately carry out torsional vibration fatigue life loss estimation on the shaft system and the vanes in time when the generator unit has torsional vibration.

Description

technical field [0001] The invention belongs to the technical field of torsional vibration safety evaluation of a steam turbine generator set, and in particular relates to a method and system for evaluating the fatigue life loss of a shafting-blade torsional vibration of a generator set. Background technique [0002] The steam turbine generator set is one of the key equipment in my country's electric power production, and the safe operation of the steam turbine generator set is fundamental to guarantee the power production. With the continuous development of the power industry, the grid structure tends to be complex, and the application of ultra-high voltage long-distance power transmission, new transmission and distribution and control technologies increases the risk of subsynchronous oscillation and subsynchronous resonance in the power grid. The units are gradually developing in the direction of high power, large span, light weight and flexibility, and multiple supports, ...

AI Technical Summary

Problems solved by technology

With the continuous development of the power industry, the grid structure tends to be complex, and the application of ultra-high voltage long-distance power transmission, new transmission and distribution and control technologies increases the risk of subsynchronous oscillation and subsynchronous resonance in the power grid. The units are gradually developing in the direction of high power, large span, light weight and flexibility, and multiple supports, which makes the shaft system lengthen, the cross-sectional area is relatively reduced, and the torsional rigidity is reduced, which leads to frequent torsional vibration failures of domestic turbogenerator sets

[0003] When torsional vibration occurs in the turbogenerator set, the shafting and blades will be subjected to varying degrees of alternating stress. The amplitude of the alternating stress is generally smaller than the allowable stress of the shafting and blades. damage; but when the amplitude of the alternating stress caused by the torsional vibration of the unit exceeds the fatigue limit of the shafting and blades, the shafting and blades subjected to the alternating stress for a long time will experience fatigue, and the fatigue life of the shafting and blades will be lost When it reaches a certain level, it is easy to generate fatigue cracks and eventually lead to fracture

[0004] In order to solve the above problems, the researchers mainly proposed to evaluate the fatigue life loss of the shafting of the turbogenerator, and analyze the torsional vibration damage degree of the shafting according to the evaluation results, but the current evaluation method is limited to the torsional vibration fatigue life of the shafting of the unit. Loss assessment ignores the impact of unit torsional vibration on blades, and lacks a better real-time online numerical assessment method

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