Multi-model Disturbance-free Switching Control For Hybrid Systems Based On Fuzzy

As modern industrial processes increase the requirements for automation and industrial process control accuracy,the systems we face are more complex.Specifically,some systems can no longer be completely described by a single continuous-time dynamic process or discrete event process,and hybrid systems can describe the process better.Therefore,hybrid systems have received great attention in the field of control,but because hybrid systems involve fields presently,there is no unified model description,so the research on its control method can only be carried out based on the problems we are studying.In view of this,this article mainly studies the hybrid switching system model that can completely describe the dynamic characteristics of the system based on the hybrid system switching system modeling theory from the perspective of engineering application,and studies when the system changes due to working conditions or large input disturbances.How to ensure that there is no disturbance of system control at the moment of system model switching.In order to effectively solve the above problems,this paper adopts a multi-model undisturbed switching control method,focusing on the undisturbed switching algorithm between the system local sub-controllers at the moment of system local sub-model switching,to ensure that the system is at the moment of model switching The control quantity is undisturbed,and the above control algorithm is applied to the control of the steam turbine system of the thermal power plant.The main work of this paper can be briefly summarized as follows:1)Aiming at the problem of large disturbances in the output of the system controller caused by the system model switching moments due to changes in operating conditions or large input disturbances in engineering applications,this paper adopts multi-model undisturbed switching control as its control strategy.And because simple PID controllers are often used to control the system in engineering applications,in addition,the dynamic characteristics of the system under a single working condition are also relatively simple,so this article is more suitable for solving engineering applications.The problem is that the local sub-controller of the system adopts a fuzzy PI controller,which dynamically adjusts the parameters of the PI controller through the output of the fuzzy controller to make up for the defect of the fixed parameter value of the conventional PI controller,which can better respond to the system under current operating conditions.The change.Two non-disturbance switching algorithms between controllers based on multi-model switching control theory are studied.One is a progressive tracking non-disturbance switching algorithm based on introducing an integrator to gradually eliminate the output deviation between the tracking controller and the effective controller.,The other is a real-time tracking undisturbed switching algorithm based on real-time solving of the initial value of the tracking controller integral and stopping the calculation of the initial integral value when the tracking controller is switched to a valid controller and keeping the integral initial value unchanged at the moment before switching.2)Taking the steam turbine system of a 350 MW unit in a thermal power plant as the application object,it is found that the steam turbine system has typical hybrid characteristics by analyzing the dynamic characteristics of the steam turbine system.The specific performance is that there are big differences in the system speed/load model structure in the impulse-to-speed-increasing condition,grid-connected power generation condition and island operation condition.Therefore,this paper firstly establishes these three models based on the method of mechanism modeling.A model under a typical operating condition,and then based on the hybrid system switching system modeling theory combined with the given time constant switching signal to obtain the speed/load hybrid switching model of the steam turbine system.And because the steam power model structure of the steam turbine system is suitable for the full range of working conditions,it reflects the influence of the opening degree of the steam turbine regulating valve and the main steam pressure on the performance of the steam turbine system,so it is established according to the mechanism modeling method.Simulate and analyze the dynamic characteristics of the built model on the Matlab/Simulink simulation platform.3)In the above-mentioned established steam turbine system models,the control effects of the two tracking and bumpless switching algorithms designed in this paper based on the multi-model switching control theory are verified.First,design the fuzzy PI controllers of the steam turbine system under three typical working conditions and compare them with the conventional PI controllers in these three typical working conditions.Then,the control valve part of the steam turbine is not considered and the part of the control valve is considered.In the two cases,the control effects of the two tracking undisturbed switching algorithms designed in this paper based on the multi-model switching control theory are simulated and verified.Finally,the control effects of the system under the two tracking undisturbed switching algorithms and the system are not added.The control effect of the disturbance switching algorithm is compared.The simulation results show that the two tracking non-disturbance switching algorithms designed in this paper based on the multi-model switching control theory can achieve the disturbance-free system control at the moment of system model switching.