Research On Fault Detection And Diagnosis Method For NPP Based On Simulation Model

Due to the complex and potentially dangerous of the nuclear power plant system,Nuclear Power Plant(NPP)'s safety has been of concern to the public.Techniques such as fault detection,fault diagnosis and system prediction for nuclear power plants can provide abnormal information and operating suggestions to reduce the pressure on decision-making of operators and reduce the danger of the system after the fault to ensure the safe and stable operation of nuclear power plants,reduce unplanned shutdown and improve the economy.In this paper,the research status of fault detection and fault diagnosis methods were analyzed.Fault detection methods based on thermal hydraulic simulation model,fault diagnosis methods for verification and the break-fault area estimation method based on the mass conservation of the system are studied.Fault verification and prediction method based on the simulation model has been explored.A fault detection and verification system were designed and developed to detect and verify the fault of nuclear power plants.The main works of this paper include:(1)Combined with the distributed thought,the method of fault detection of nuclear power plant based on thermal hydraulic simulation model was studied.System was divided to few parts according to the actual measuring point.The simulation model of the nuclear primary system was established to produce the residual vector.The method of principal component analysis was used to analysis the residual vector,which realizes the fault detection and location of the actual system.(2)The fault diagnosis method based on random forest algorithm was studied,and the fault diagnosis module of the nuclear assistant system was established by the off-line fault data.The system collects the values of the actual measuring points of the system on-line.The structure of the data was identified to diagnose the type and location of the fault.(3)The method to estimate the area of the failure area based on the mass conservation ofthe system was studied.The leakage rate was estimated by monitoring the change of the total mass of the working fluid in the system.The area was approximately estimated for fault verification.(4)The subsystem models and the reactor coolant system simulation model wereintegrated together to get the model of the primary loop system.The way of the fault loading,and the verification method was studied.(5)The auxiliary system was taken as the study object,a fault detection and verification system based on the thermal hydraulic simulation model was developed by using C# 4.0programming language.The fault detection and verification system were verified by the simulator of the Fuqing nuclear power plant.