Repairable T-S Dynamic Fault Tree Analysis Under CCF And Reliability Analysis Of Wind Power Hydraulic System

With the continuous improvement of the development level of manufacturing industry,the reliability requirements of mechanical products are becoming higher and higher,which makes the reliability problem more and more attention.Fault tree analysis is a main method for reliability analysis.In view of the repairability and dynamic failure behavior of mechanical products,the traditional fault tree analysis method has some limitations.Therefore,the T-S dynamic fault tree analysis method and the importance degree algorithm of repairable system are deeply studied.Furthermore,the influence of common cause failure on reliability model accuracy is considered,and the T-S dynamic fault tree analysis method for repairable system under common cause failure is proposed.The proposed method is applied to the reliability analysis of the hydraulic system of wind turbine,and the correctness of the proposed method is verified.Firstly,aiming at the state transition of multistate system,the state description rules of time period and event description rules of multistate T-S dynamic fault tree are described by using the T-S dynamic fault tree analysis method of repairable system,and the input and output rule algorithms of the T-S dynamic fault tree are given.The minimum maintenance after the event,maximum maintenance after the event and preventive maintenance according to the situation are analyzed and calculated.Secondly,considering the importance of final event,the significance analysis method of repairable system T-S dynamic fault tree is used.On the basis of explaining four basic concepts of significance,namely probability significance,critical importance,risk performance value and risk reduction value,different maintenance methods are used to analyze and compare the change of importance of bottom event.The high efficiency of preventive maintenance based on condition is further verified.Furthermore,considering the existence of common cause failure makes the system more prone to failure,the explicit modeling method is used to combine the common cause failure model with the dynamic fault tree,and the T-S dynamic gate under common cause failure is given,and the T-S dynamic fault tree analysis method of repairable system under common cause failure is proposed.The feasibility of the proposed method is verified by reliability analysis in machining center turntable system.Finally,taking the hydraulic system of a wind turbine as an example,the reliability analysis is carried out.By analyzing its working principle and failure mechanism,the importance changes of the system with or without maintenance are obtained;the proposed method is applied to obtain a curve of the failure probability versus operating time for the hydraulic system with and without considering the existence of common cause failures,which verifies the correctness of the proposed method.