Primary Loop Modeling Research On Larger Pressurized Water Reactor Nuclear Power Plant

The expansion of large capacity nuclear power changes the power grid operation model,which has brought an increasing influence on the safe and stable operation of the grid,but brings new problems such as the difficulty of peak and frequency regulation.In order to master the operation characteristics of nuclear power unit to ensure the stable operation of the unit and the power grid,more accurate model suitable for power grid stability analysis is pressing.However,some of the existing models are not practical.On the one hand,due to their high dimension,it is not appropriate for the analysis of large capacity nuclear power units.On the other hand,because of too many assumptions,the simulation conditions are limited.Therefore,it is of great significance to establish model of large-capacity nuclear power unit suitable for power grid stability analysis.For most of the nuclear power generating units of operation and under construction in China are pressurized water reactor(PWR)type,and the capacity of these units are usually of million-kilowatt-class,so this paper focuses on million-kilowatt-class PWR nuclear power plant,mainly including the research on detailed model establishment and the model simplification of nuclear power plant.The work of this paper as following:First of all,This paper introduces the main equipment of the nuclear power plant and its basic working principle,then puts forward the detailed model of pressurized water reactor nuclear power unit based on MATLAB/Simulink.The model mainly including the nuclear reactor system,pressure vessel and main pipes,activity system,reactor power control system,reactor temperature control system,coolant pump and steam generator.Some module is optimized,so that it can more accurately reflect the dynamic response of the nuclear power unit.Secondly,combined with a numerical example,this paper makes a study on the interaction between the nuclear power unit and the power grid.Analysing the transition of the internal variables to a stable station when the load step increase and decrease.Researching the dynamic response to the grid frequency and voltage fluctuations.Finally,based on some assumptions,least square(LS)method was used to simplify the nuclear island through the analysis of the nuclear island structure.Analysing the situation of the simplified model in case of other conditions combined with numerical examples.The simulation results show that the model can accurately represent the dynamic performance of nuclear power unit,and provide an effective tool for further research on the interaction between power grid and large-capacity nuclear power plant.