Investigation On Fault Diagnosis Technology Of The Condenser Based On Qualitative Simulation Theory

Qualitative simulation is to describe reasoning theory and reasoning process with symbols or numerical values and it is the field of system simulation and artificial intelligence theory.Besides,it is an effective way to find fault components of complex systems by qualitative reasoning.To complete the fault diagnosis process,in this article,QSIM is taken as the research method and the condenser is the object which has certain theoretical significance and practical value.In this article,on the basis of collecting and reading a large number of relevant papers,it is combined the basic theory and method of qualitative simulation systematically.Furthermore,it uses R language and develops the calculation program independently which can validate program,diagnose fault and integrate the QSIM system.In the process of program development,the following problems are mainly solved: in the process of qualitative derivation,the global filtering is improved according to the phenomenon of state cycle generated in the results.Besides,in order to make the algorithm applicable to engineering practice and fault diagnosis,a one-dimensional constraint non-negative is added,and their constraint filtering conditions are given correspondingly.A variety of colors are added to the results of qualitative simulation which can describe the behavior state tree with global explanation and global filtering reason.In order to draw the variation diagram of the required parameter,QISM can track the required parameter states,and use arrows to show the variation of the parameter at the time-point,making the simulation result more intuitive.For the condenser structure is complex and there are many different kinds of faults in fault diagnosis,this paper simplifies and abstracts the condenser model into a qualitative model and defines the constraints and the initial state by changing the steam inlet pressure,hot well drainage pressure,inlet steam specific enthalpy,cooling water flow,inlet cooling water specific enthalpy,and observes the change of other parameters to implement fault diagnosis.According to the calculation and deduction of qualitative model of condenser by QSIM program,the variation of major parameters in fault such as steam temperature in shell side,outlet temperature in cooling water,specific enthalpy of outlet cooling water,specific enthalpy of condensed water in hot well,pressure in shell side and average specific enthalpy of steam in shell side was obtained,and the corresponding fault diagnosis table was established according to the simulation results.The results show that the developed QSIM have a strong reliability,which lays a foundation for the application of qualitative simulation in engineering,especially when the object has incomplete knowledge or information.