Research On Fuzzy Immune PID Algorithm And Its Application To Dry Section Of Tissue Paper Machine

In recent years,with the improvement of people's living standards,the demand for tissue paper has increased year by year,which promotes the development of the paper industry.However,a lot of resources are needed in the tissue paper production.Under the background of advocating low-carbon and environmental protection,it is an urgent task for paper industry to achieve energy saving and promote green production.The drying section of tissue paper machine is the main energy-consuming section part of the papermaking process,and its steam consumption cost accounts for more than 50% of the total steam consumption cost of papermaking process.Research shows that differential pressure of dryer inlet and outlet and zero-level of closed hood are important control variables of the drying section.And their control effect is directly related to the energy consumption and paper quality.But they have time-delay,time-varying,nonlinear and other characteristics,it is difficult for conventional PID control to achieve the desired control effect.The analysis shows that whether PID control can be applied to time-delay,time-varying and nonlinear controlled objects depending on the tuning of PID parameters.Fuzzy immune algorithm is an intelligent algorithm combining fuzzy control and immune feedback mechanism.It can adjust the PID parameters automatically according to the characteristics of the controlled object,which can obtain good control for it.Under the support of science and technology coordination innovation project in Shaanxi Province(2016KTCQ01-35),the fuzzy immune algorithm is researched.Then the results of research is applied to the drying section of tissue machine production line in Baoding,Hebei to improve the control effect of system and the energy consumption of dry section.The main work of the thesis is as follows:I.Analysis of Factors Affecting Energy Consumption and Related Process Variables in Drying Section of Tissue Paper MachineThe process flow of the dryer section system of the tissue machine is introduced,the factors affecting the energy consumption are analyzed,and the model of dry section energy consumption is established.The characteristics of differential pressure of dryer inlet and outlet and zero-level of closed hood are analyzed and related mathematical models are established.A fuzzy immune PID control scheme is designed for the former.A fuzzy immune feedforward feedback control scheme is designed for the latter.II.Parameter Tuning of PID Based on Fuzzy Immune AlgorithmAiming at the control problems of time-delay,time-varying and nonlinear controlled objects in industrial process,fuzzy immune algorithm is proposed for tuning of PID(FI-PID)parameters based on the analysis of fuzzy control and immune feedback mechanism.For the common model of industrial process control,including the differential pressure control model of the dryer inlet and outlet,proposed algorithm is compared with Z-N,immune PID(I-PID)and fuzzy PID(F-PID)for simulation experiment.The results show that set value tracking performance,anti-interference performance and robust performance of system based on FI-PID are better.III.Optimization of Immune Parameters Based on Genetic AlgorithmIn the fuzzy immune algorithm,the selection of immune parameters is often used in the experience piece-try method,which takes a long time and the parameters are not necessarily optimal.In order to overcome the problem of large overshoot and slow response speed caused by improper selection of immune parameters,genetic algorithm of global optimization is applied to optimize immune parameters.A genentic fuzzy immune PID(GFI-PID)algorithm is designed.For the common model of industrial process control,including the differential pressure control model of the dryer inlet and outlet,proposed algorithm is compared with FI-PID.The results show that GFI-PID improves the control performance.A fuzzy immune feedforward feedback(FIFF)control scheme is designed by combining the improved algorithm with feedforward feedback,and it is applied to simulate the zero-level control system of hood.The results show that compared with conventional control methods,the control effect of FIFF is better.IV.Design and Implementation of Control System for Drying Section of Tissue MachineThe corresponding control scheme is designed based on the analysis of control points of the drying section of tissue machine.With SIEMENS S7-300 PLC as the main control hardware and STEP7&WinCC as the development software,a set of DCS system of drying section of paper machine is designed.The fuzzy immune PID algorithm is applied to the drying section control system of tissue paper machine based on OPC technology,which realizes the communication between MATLAB and WinCC.The research results of this paper have been applied to the tissue paper factory in Baoding,Hebei.The operation results show that differential pressure fluctuation range of dryer inlet and outlet is controlled within 4%,and differential pressure fluctuation range of zero-level in closed hood is controlled within 3%.The deviation is reasonable and the control effect is good.The application results show that the average ton of paper steam consumption is reduced by about 9.1%,which achieves good economic benefits for the papermaking enterprises.