| Energy is an important foundation of modern social and economic development.With the development of power system in China towards large capacity,ultra-high voltage and long distance,how to ensure the safe and stable operation of power system is very important.In the nuclear power industry of our country,there are many events related to shutdown caused by instrument control card.During the five years starting in 2006,the circuit board caused 112 accidents such as shutdown and load reduction,including 48 shutdowns,40 load reduction,and about 5.3 million MWe of power generation losses.Therefore,it is very necessary to study the reliability test of the instrument control card in nuclear power plant.The dual-channel absolute value alarm studied in this paper is one of the instrument control card.The main contents and achievements of this paper are as follows:(1)This thesis analyzes the working principle of instrument-control card parts and divides its modules,introduces the double-channel absolute value alarm card parts as an example in detail,and provides a large number of references for the daily maintenance and fault maintenance of power station personnel.(2)The Failure Mode and Effect Analysis method are discussed and applied to the hard fault diagnosis process of the circuit.By FMEA method,the net table can be generated,which contains a wealth of card information.By Pspice software to realize the fault impact analysis of the circuit,the fault data is automatically exported to realize the automatic flow of the whole process.(3)An improved FMEA fault diagnosis method is proposed in the traditional analysis method.The traditional fault tree analysis method needs to establish fault tree model frequently,and the fault tree established by each top event is different and not universal.By studying the method of transforming FMEA table into dependency matrix,the table language is transformed into digital formula,and the fault-test point dependency matrix is established.Finally,on the basis of this matrix,the optimal fault diagnosis tree is automatically generated by using the heuristic search AO* algorithm with or graph,and the fault isolation is realized automatically,and the cost of testing is minimized.This method does not need to re-establish fault diagnosis tree for each circuit fault,which is better in time and diagnostic efficiency than the traditional method.In addition,based on the single fault diagnosis,the test set and hidden fault of each fault mode are analyzed,and the topology diagram of multi-fault diagnosis system of card parts is obtained.(4)On the basis of scientific research project,the soft fault of double channel absolute value alarm card parts is pre-studied,and the interval analysis method based on Taylor expansion is proposed.Taking the second-order filter circuit of the card as an example,the relationship between the circuit characteristics and the variable parameters is calculated from the mathematical point of view by selecting the circuit characteristics and the variable parameters that need to be studied.According to the variable parameter interval of components,the interval approximate solution of circuit characteristics is obtained,and the reliability of components is studied according to the calculated interval approximate solution.Finally,the feasibility of this method is verified by simulation.(5)The whole system scheme of card piece is designed,the function of software system is designed,the software interface is designed according to the requirement of software function,the structure of software system is analyzed,and the function of on-line simulation and fault diagnosis of card piece circuit is realized. |
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