Research On Intelligent Control Algorithm Of Outlet Temperature Of Heat Exchanger

Heat exchanger is a commonly used heat transfer equipment in industry.It is of practical significance to choose a suitable control scheme to stabilize the outlet temperature of heat exchanger.In this paper,the third generation model predictive control-Predictive functional control algorithm(PFC)is applied to the heat exchanger outlet temperature control.The PFC algorithm is improved,and the improved predictive functional control(IPFC)scheme is simulated and compared.The main research contents are as follows:1.Firstly,the control characteristics of the heat exchanger system are analyzed,and the formula of amplification coefficient of four channels is given from the static characteristic analysis,and the transfer function formula of four channels is given from the dynamic characteristic analysis.The model of four channels of heat exchanger is established through the actual operation data of heat exchanger equipment in industrial field.2.Secondly,the characteristics of the incremental PID control algorithm and the PFC control algorithm are analyzed,and the commonness of the two algorithms to solve the deviation is utilized.The theoretical formula of PID control is substituted into the quadratic performance index formula of the PFC algorithm,and the PFC algorithm is improved,so as to synthesize the advantages of the two control algorithms.The IPFC control algorithm is compared with the traditional PID algorithm and PFC cascade PID algorithm.The results show that the improved algorithm has faster response speed and good control effect when the model parameters change.3.Third,aiming at the problem that the improved algorithm needs to adjust many parameters and manual trial is difficult,a particle swarm optimization algorithm(CFPSO)with compression factor is proposed to optimize the IPFC parameter control scheme.Through the simulation experiments also show the effectiveness of the proposed optimization algorithm optimization.4.At last,two cascade control schemes are proposed to solve the problem that the heat exchanger may be affected by the large disturbance of the outside world.The first is a cascade control scheme based on IPFC,and IPFC controller is used as the main controller,and the cascade control loop is used to suppress the interference.The simulation comparison with the two cascade control schemes verifies the superiority of the cascade control scheme.The second control scheme is based on IPFC feedforward cascade compound control scheme.The feedforward control is used to compensate three groups of disturbances which can be measured but cannot be used as control variables in the input variables of heat exchanger,thus greatly reducing the influence of interference on the control system.The simulation analysis of three types of disturbance under model adaptation and model mismatch proves that the scheme has superior effect on interference suppression.