The Controllability Of The Reactor Power Control System

In order to make sure the safe running of nuclear power plant,reactor power control system is necessary to the safety and stability of reactor during load-following operation.Due to the characteristics of highly nonlinearity,variable parameters and strong coupling of the reactor power control system,traditional power control methods cannot meet the safety and stability of the reactor operation when the reactor power has a large range.The way that combining the modern control theory with classical control theory can design a controller with better system dynamic performances.It is the primary mission to analyze the controllability of the power control model before a controller based on the modern control theory is designed.In this paper,the controllability of the point reactor neutron kinetics equations is studied.According to the effect on the reactivity,the point reactor neutron kinetics equations neglecting the reactivity feedback and the point reactor neutron kinetics equations with concerning the temperature reactivity feedback are investigated.Then the controllability of the two different equations that introduced one-group,two-group,three-group and six-group delayed neutron is analyzed respectively by the method that the analytical derivation method and numerical calculation method.The results obtained by the two methods are different.The analytical derivation method proves that the point reactor neutron kinetics equations are controllability in any case.But the numerical calculation method gives a different conclusion that the point reactor neutron kinetics equations neglecting the reactivity feedback is uncontrollability when the equations introduced six group delayed neutron and the point reactor neutron kinetics equations with concerning the temperature reactivity feedback are uncontrollability when the equations introduced three group or six group delayed neutron.The main reasons for causing the two different results are the ill-conditioned of point reactor neutron kinetics equations and the method used to calculate the controllability discriminant matrix.At last,state feedback controllers are designed based on state feedback theory for the point reactor neutron kinetics equations neglecting the reactivity feedback which introduced one-group,two-group,three-group and six-group delayed neutron.The controllers are simulated and the simulation result indicates that the feedback controllers can control the system when the equations introduced one-group,two-group and three-group delayed neutron,but the control effects are getting worse with the number of delayed neutron group increasing.The controllers cannot control the system when the equations introduced six group delayed neutron.The result is in contradiction to the conclusion deduced by analytical derivation method.Through the comparison analysis,the reason for the contradiction is the limitation of the controllability theory when it is applied to analyze quantitatively by numerical calculation method and the index that control number and control limit are proposed to describe degree of the controllability of the system.