| The control system is the “nerve centre†system of marine nuclear power plant, itscontrol quality directly influences the function realization of marine nuclear power plant. Thecontrol strategy of the secondary circuit of marine nuclear power plant is the effective meansfor realizing the higher automatization of the nuclear power plant, improving the level of thedistributing control system (DCS) of the secondary circuit system of the nuclear power plantand improving the credibility of the secondary circuit system. Therefore, it has greatsignificance for improving the functional performance and the combat capability of marinenuclear power plant.Correlative literature and datum which are about the nuclear power plant and nuclearsubmarines at home and abroad are referred and analyzed. This paper firstly establishes thesimplified lumped parameter models for the secondary circuit of the nuclear power system, byusing two-phase lumped parameter modeling methods. These models mainly comprise thesimplified lumped parameter mathematic model for steam generator, turbine mathematicmodel, the simplified lumped parameter mathematic model for condenser, pump mathematicmodel and the simplified model for pipeline and valve. These mathematic models above aresimulated on Matlab/Simulink platform. The idea of modularization modeling is implementedfor the encapsulation of each subsystem models. Modeling calculation is carried out on thebasis of the simulation models to verify the dynamic characteristics. The correctness of thesecondary circuit mathematic models is shown by the simulation results which lay atheoretical foundation for formulating the control strategy of the secondary circuit of marinenuclear power plant.The conventional PID control system of the secondary circuit of nuclear power plantsbased on classical control theory is designed, using the simulation model of the secondarycircuit system established before. The design method of control system for nuclear powerplants and nuclear submarines is referred. The control systems of the secondary circuit ofnuclear power system mainly contain reactor operation control system, steam dischargingcontrol system, steam generator water level control system, steam turbine-generator unitspeed-power control system, condenser water level control system, vacuum and condensatesubcooling degree control system and pump speed control system. Modeling calculation ofreducing load is carried out to verify the validity of the control systems designed above. Thesimulation results prove that the conventional PID control system of the secondary circuit based on classical control theory could meet the need of the targets of marine nuclear powercontrol system.The fuzzy control system for water level control of steam generator is designed based onconventional PID control, according as fuzzy control theory. Three level control methods aredesigned: fuzzy level control, fuzzy adapting PID level control and fuzzy-PID level control.Simulation results show that fuzzy control has such excellence as smaller overshoot, shorteradjusting time and stronger robustness. It especially fits to nonlinear systems like steamgenerator with multivariable, large time lagged and stronger coupling. Adaptive neuro-fuzzylevel control system of steam generator is designed based on the fuzzy control system,according as neuron network control theory. Simulation results show that the adaptiveneuro-fuzzy level control system has not only inference ability of fuzzy control system, butalso adaptive and self-studying abilities. It is a more perfectly intelligent control strategy.The intelligent coordinated control system (CCS), namely reactor-steam generator-steamturbine CCS, at system level is designed to solve the problem of inside and outside energyunbalance of the secondary circuit. The intelligent coordinated control system acts when themain steam pressure deviation of the secondary circuit is bigger than the set value. It couldopen the feedwater valve of steam generator and command control rods to act in advance,meanwhile, restrict the steam valve of steam turbine not to open quickly. As a result, therapidity of turbine’s response to power load is ensured, so is the stability of the main steampressure.Finally, a series of control strategies based on the modeling simulation above areproposed for our national new type marine nuclear power plants, including the controlstrategies at system level and the control strategies at device level: the overall coordinatedcontrol strategy, the water level control strategy of steam generator, the integrated controlstrategy of steam turbine, the centralized control strategy of pumps and valves and theoperation management of the secondary circuit of nuclear power plants. |
