Research On Steam Generator Water Level Model Predictive Control

Steam Generator （SG） is an important connection equipment in Nuclear Power Plant （NPP）of Pressurized Water Reactor （PWR）. Not only does it play the role of energy transfer andconversion in PWR, but it is a primary equipment to isolate the radioactive substances of theprimary loop. The normal work of SG directly relates to the safe operation of NPP. Therefore,the water level of SG is an important monitoring and control parameter, and it is also animportant index to estimate whether SG is operating normally. In order to ensure the PWRoperating safely, it is necessary to control SG water level in the reasonable range.SG is a complex dynamic process which has the characteristics such as non-minimumphase and strong disturbance, and highly non-linearity. In this thesis, SG’s discrete nominalmodel based on simplified model that Irving put forward, is proposed to build the polytopicLinear Parameter-Varying （LPV） model of SG which can describe the system’s uncertaintyand non-linear characteristics effectively with dependent parameter. Single PID controlsystem and cascade PID control system are designed based on polytopic LPV model. Thesimulation results show that the cascade PID control system has better control performancethan the single PID control system.At first, min-max model predictive control system andH₂/H_∞multiple objectivemodel predictive control system are designed based on the polytopic LPV model in this thesis.Optimization problem of these control systems is transformed to equivalent linear matrixinequality （LMI） convex optimization problems.The simulation results verify that theclosed-loop systems are feasible. Secondly, the composite double controllers systems areresearched on the basis of min-max model predictive control system andH₂/H_∞multipleobjective model predictive control system by adding a PID controller respectively.Thesimulation results prove the feasibility of these two kinds of control system.At last, the system performance of the single PID control system, the cascade PIDcontrol system and two kinds of the composition double controllers system are evaluated bycalculating their values of Mean Square Error（MSE） which are also compared with the MSEvalues of SG water level control systems which are designed respectively by Fakhrazari andBoroushaki. The results show that the performance of the control systems designed in thisthesis is better than Fakhrazari’s and Boroushaki’s.