On-line Estimation Of Steam Turbine Rotor Life Loss

On-line estimation of turbine rotor life loss provides technical support for routine maintenance and stress control. It prevents non-expected break down caused by inappropriate use and maintenance, thus keeps power plants (especially nuclear power plants) under normal operations.This paper studies the on-line estimation/computation of turbine rotor life loss and proposes a finite element model of rotors. A method to model process parameter and rotor life span is presented, using non-linear decomposition and model identification. Details are as follows:1. According to finite element and life loss calculation theory, this paper adopts the largest local stress-strain method and draws the following conclusion:computation model of life loss for a particular material is a static nonlinear model in the premise of known stress; 2. Use finite element software to simulate the complex structure of turbine rotor and working environment, and apply cold start impulse on rotor finite element model to obtain rotor temperature and stress data for further analysis;3. It is found that the model of rotor temperature and stress is a dynamic linear model. The model of control impeller roots temperature and stress is identified by MATLAB software and it is proved to achieve good accuracy;4. The nonlinear relation between process parameter and rotor life loss is decomposed into static nonlinear and dynamic linear model, while constructing an estimation model of them and being simulated in MATLAB/SIMULINK. For the algorithm modules used in SIMULINK have the corresponding algorithm modules in the DCS system, so the simulation model can be directly converted to SAMA diagrams in the DCS, and achieve the real-time calculation of the loss damage. Experiments on a domestic 300MW steam turbine are shown to demonstrate the feasibility of the proposed method to model rotor life loss under cold starting conditions and high pressure.