Abstract
The report describes an expert system of probability type for diagnostics and state estimation of steam turbine technological subsystems components. The expert system is based on Bayes’ theorem and permits to troubleshoot the equipment components, using expert experience, when there is a lack of baseline information on the indicators of turbine operation. Within a unified approach the expert system solves the problems of diagnosing the flow steam path of the turbine, bearings, thermal expansion system, regulatory system, condensing unit, the systems of regenerative feed-water and hot water heating. The knowledge base of the expert system for turbine unit rotors and bearings contains a description of 34 defects and of 104 related diagnostic features that cause a change in its vibration state. The knowledge base for the condensing unit contains 12 hypotheses and 15 evidence (indications); the procedures are also designated for 20 state parameters estimation. Similar knowledge base containing the diagnostic features and faults hypotheses are formulated for other technological subsystems of turbine unit. With the necessary initial information available a number of problems can be solved within the expert system for various technological subsystems of steam turbine unit: for steam flow path it is the correlation and regression analysis of multifactor relationship between the vibration parameters variations and the regime parameters; for system of thermal expansions it is the evaluation of force acting on the longitudinal keys depending on the temperature state of the turbine cylinder; for condensing unit it is the evaluation of separate effect of the heat exchange surface contamination and of the presence of air in condenser steam space on condenser thermal efficiency performance, as well as the evaluation of term for condenser cleaning and for tube system replacement and so forth. With a lack of initial information the expert system enables to formulate a diagnosis, calculating the probability of faults hypotheses, given the degree of the expert confidence in estimation of turbine components operation parameters.
Highlights
At present, the research on the state parameters of turbine unit equipment, forecasting of their changes and determination of their residual life has become widespread [1,2,3]
PSM can have a hierarchical structure, which shows at each level in a graphical form the relationship of various faults leading to more serious malfunctions
The specific filling of the knowledge base, that is, the formation of its content and the designation of a priori probabilities for the hypotheses and the ‘price’ of evidence, is carried out, as a rule, by the method of expert evaluations employing the specialists dealing with thermo-mechanical equipment of thermal power plants, taking into account the specific features of the equipment at a particular station
Summary
The research on the state parameters of turbine unit equipment, forecasting of their changes and determination of their residual life has become widespread [1,2,3]. The knowledge base contains information about STU failures as fault hypotheses and a table of evidence. The a priori probability of fault hypotheses and the evidence value are determined by the experts. The user sets the values of pieces of evidence and the ES calculates a posteriori probabilities of hypotheses and forms a conclusion about the cause of failure. The knowledge bases of the ES for vibration diagnostics of turbine rotors, bearings and other components include a description of 34 defects and 104 diagnostic features These defects cause a change of vibration state of the turbine unit. The output mechanism interprets the rules and uses the facts of the knowledge base to solve the problems posed It makes a diagnosis based on the information contained in the database. PSM can have a hierarchical structure, which shows at each level in a graphical form the relationship of various faults leading to more serious malfunctions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
