Optimization And Simulation Of Steam Generator Level Control Based On NURES

The steam generator is a non-linear,large time-delay,complex system.Under the conditions of rapid fluctuations in the steam flow rate,the phenomenon of "false level" of the steam generator is very serious,and the control is very difficult.The cascade PID control is widely used in steam generator liquid level control of the pressure water reactor nuclear power plant.According to operational experience feedback from nuclear power plants,there are some problems with current steam generator level control.This paper analyzes these issues in detail and strives to optimize the current scheme.Based on the analysis of the operating mechanism of the steam generator,this paper theoretically analyzes the characteristics of the "false level" at different parameters in different power stages,and proposes a variable gain PID control scheme.At the same time,according to the feedback from the operation experience of the power plant,in view of the poor liquid level control performance under low load,a bypass feed water flow measurement is proposed to optimize the control scheme under low load.In view of the shortcomings in the design of the feed water control valve switching process,the use of flow rate as the set point for switching determination is proposed.The "false level" phenomenon of the steam generator is inherent to the two-phase change of the vapor and liquid of the water in the steam generator.And this paper analyzes the severe conditions of the steam generator liquid level control based on the "false level" phenomenon.By analyzing the response of the transient process parameters in detail,it is proposed that the feed water regulating valve raise the opening in the beginning of the transient to avoid the steam generator level drop.The nuclear power plant control system simulation platform NURES is used to simulate and verify the proposed optimization scheme.Simulation results show that the optimization scheme can achieve the expected resultsThe optimization suggestions for the steam generator level control in this paper can be used as a reference for the reconstruction and optimization of the in-service nuclear power plant,and it can also be taken into consideration in the design of new nuclear power plants.