Research On Risk Evaluation And Diagnosis Methods Of Rotor Thermal Bending Fault For Steam Turbine Generator Unit

Steam turbine generator unit based on its high-parameter, large capacity, it will be a huge loss when accident happens. One of the most typical modes is the thermal bending faults of rotors. After decades of effort many experts and scholars at home and abroad have made great achievements in the field of fault diagnosis. But there still exist some issues that need further breakthroughs in bottleneck. From a single failure to break through multiple faults, under the harsh and complex conditions, the steam turbine generator unit is often complicated by the presence of variety of fault phenomenon when a failure occurs. We need to establish a more reasonable mathematical and mechanical model, clarifying various fault conditions associated, thus to have in-depth study of the dynamic evolution of faults and fault symptoms. Achieve a break through from qualitative to quantitative, after qualitative determination of the cause, In order to develop a more rational decision-maintenance and achieve the breakthroughs from the strong faults research to the weak faults research, we need to find a reasonable and feasible approach to the severity of the failure thus to make the real-time analysis and evaluation.Based on the bottlenecks above, we need to make early fault diagnosis and take measures to repair as soon as a fault is given. I start this paper from the research of the mechanism of fault by FTA and FMEA analysis. Then combine risk assessment on the basis of FMEA quantitative analysis, including the inherent risk analysis and the real time risk analysis, thus to achieve early warning. So that we can find out the potential failure modes and provide a powerful guarantee for further fault accurate diagnosis. This thesis will commence the following aspects.Firstly, I find fault causes and underlying parameters by FTA analysis and then identify the relationship between the cause, influence and maintenance measures combined with FMEA analysis. By this means Ⅰ establish a correspondence between the parameters and faults and make a more perfect knowledge system.Secondly, I make a risk assessment for the various systems and subsystems. By calculating the inherent risk and the real-time risk of equipment we can measure the severity of the fault. Finally calculate and compare the deviation of risk and find the cause of the fault, thus to achieve an early warming.Finally, I make a research on the quantification and acquisition method of fault symptom and obtain fault symptom set. Then we can achieve the fault category by the method of fuzzy fault diagnosis. Next we can find out the reasons, the impact and the measures by FTA and FMEA method. The final analysis is validated through a case.