Dynamic Modeling And Controller Tuning Of Water Level Of AP1000 Steam Generator

Due to its high energy density and low pollutant emission,nuclear energy has received increasing attention worldwide.The AP1000 system,which was designed based on AP600,is one of the most safe,advanced and popular units among the generation III+ passive safety nuclear power plants.Steam generator is thermal-hydraulic component of AP1000 coolant system for exchange of heat between the primary and secondary circuits and provides steam for generating electricity.Therefore,the proper water level control of steam generator is of a great importance in order to function properly.However,there are many difficulties to tuning the water level control system.On the one hand,the dynamic behavior of water level is rather complex,with open loop unstable,highly non-linear characteristics and strong inverse response behavior due to its nonminimum phase characteristics.On the other hand,the structure of water level control system has strong coupling,and it's not allowed to modify or restructure the controller.Facing the aforementioned challenges,the main contributions of this paper are listed as follows:(1)Accurate transfer function models based on American Westinghouse CENTS simulation platform by identification.Water level control system for AP1000 steam generator is transferred into equivalent cascade control system.And then analytical tuning rules is derived based on the equivalent cascade control system and internal model control method.(2)Mechanism-identification modeling method is proposed as a result that no identification experiment is allowed in real plant.This method only requires normal operation data or standard test data of AP1000,and achieves accurate models on overall working conditions.(3)Three impulse control simulation platform of steam generator based on mechanism model is built,and tuning is completed as well.Furthermore,the non-linear and coupling of steam generator can be well analyzed.