Research On Reactor Control Rod Out Of Step Fault Diagnosis And Fault Tolerant Control Method

The three-dimensional power distribution of the reactor core reflects the operating status of the reactor,which is directly related to the safety of the reactor.Among them,the control rod is an important means of reactor power control.Under certain working conditions,when the main control rod group that adjusts the power is not in the specified rod position area,it is usually called a control rod out-of-step fault.When the number of steps out of step is large,it may cause unexpected shutdown.When the number of out-of-steps is small,it is also necessary to determine the position of the out-of-step control rod in a short time and correct or tolerate it.Since the control rod drive mechanism,the core,and the neutron detector as a whole constitute an open-loop control system,whether the control rod out-of-step failure occurs,the number of steps in the control rod out-of-step,and what kind of fault-tolerant control strategy is provided all have an impact on the reactor power Its control and safe operation have a major impact.This paper takes the pressurized water reactor as the research object,and uses intelligent methods to establish the control rod out-of-step state monitoring and fault diagnosis and fault-tolerant control system.Firstly,the reactor core is divided by the nodal method.Based on the REMARK program,a core simulation program is written on the.NET platform to establish a three-dimensional reactor core power distribution model.Based on the neutron diffusion equation,the neutron flux separation variables are solved by amplitude function and shape function,and each cross-sectional parameter is obtained by fitting formulas,and then the core power level distribution,reactivity and neutron count are obtained,and the accuracy of the core physical model is verified by comparison with reference values.Secondly,for the control rod out-of-step fault,the neutron count under different working conditions is calculated through the core physical model,and the abnormal state module,the working condition judgment module and the state monitoring module are established.On this basis,according to the neutron count,the out-of-step position,and the number of out-of-steps,the BP neural network is used to establish a fault diagnosis module under different working conditions.Through the test results of three working conditions,the real-time and reliability of the state monitoring and fault diagnosis system is verified when the control rod is out of step.The state monitoring module is improved according to the changing trend of the neutron count under different working conditions.Finally,according to the fault diagnosis results,the fault-tolerant control system based on SQP algorithm and genetic algorithm(GA)is studied.Through testing,it is concluded that the fault-tolerant strategy has a permissible impact on the radial and axial power of the core.Within the operating range,and the total power of the core after fault tolerance is closer to the set value of power.The results of the case analysis show that the calculation speed of SQP algorithm is obviously faster than that of GA algorithm,but it has more iterations.GA algorithm is complicated,but the number of iterations is less.When the problem is relatively complicated,the performance of GA algorithm is superior.On the premise of ensuring the safe operation of the reactor,the dynamic quality of the control process can be effectively improved by this thesis.The research results have certain theoretical reference significance for the research on the intelligent control design of the reactor.