Fault Diagnosis Of High Pressure Heater Based On Qualitative Simulation

Qualitative simulation is a branch of system simulation and is also a across subject between system simulation and artificial intelligence. It differs from quantitative simulation because of they aren't the same method system which makes every effort to reach the non-digitization, overcomes the quantitative simulation's weakness, processes the input, making model, behavioral analysis and output of the simulation with the non-digital method and ascertains system qualitative behavior description through qualitative model.The faults diagnosis is a important application of qualitative simulation based on qualitative method. It is better than the quantitative simulation in the aspect of dealing with incomplete information using the system in-depth knowledge.The high-pressure heater is the main equipment of regenerative system in the thermal power plant. Taken the high-pressure heater as the simulation object, the dynamic mathematics model of heater was established and commutated in the paper. The results gave the time response curves of the working pressure, the water level and the temperature of outlet water when the pipes leaked and condensing-water valve failure and so on. The qualitative mathematical model was established base on the dynamic model of the high-pressure heater. The qualitative simulation gave the qualitative change trend of the main parameters when the water level default, and than certificate the simulation results are correct though the comparison of dynamic response curves.This article includes three parts. The first part briefly introduced the development of qualitative simulation and the diagnostic technology based on qualitative simulation and expanded the correlation restraint and upbuilded the condition restraint based on the QSIM algorithm foundation; The dynamic mathematics model of high-pressure heater was established and commutated in the second part. Summing up the quantitative equation of feed water flux and the leakage flux and the parameters of the causal relationship, the qualitative model was also established on the basis of the dynamic model, the characteristic of the thermal system and the high-pressure heater's structure. The third part according to the established high-pressure heater's qualitative model, take the water service level as original state, produces all possible successors of the correlation parameters. Through filtrating, obtain the faults collection of the water level's abnormity of the high-pressure heater.