Research And Application Of Active Disturbance Rejection Control In Gas Flow Facilities

As the important basis of flow metrology and measurement technique,gas flow facility is built for the test,transmission and calibration about the performance of various gas flow meters.Because of the compressibility of the gas,the research process of gas flow meters needs under the conditions of different pressure and flowrate,which is provided by the gas flow rig.With the more widespread application of gas flow meters,the performance of the facility needs to be further boosted.Compared with the liquid flow measurement,there are still many control problems in the gas flow measurement system which involves a variety of process parameters.Active disturbance rejection control(ADRC)is an advanced control algorithm based on the combination of PID control and modern control theory.The kernel of the ADRC treats internal uncertainties and external disturbance together as total disturbance,and then it can be accurately estimated by the extended state observer(ESO)and cancelled out by the control law.It reduced algorithm dependency on mathematical model,and improved system robustness.Nowadays,ADRC technology has been applied in many practical systems.In order to solve the control problems in the application of gas flow facility,based on ADRC algorithm,this paper completed this following works:Firstly,regulating valves can realize switching between different flow and pressure points of the gas flow rig.It is known that the flow rate and the pressure in the test pipeline are strongly coupled,which caused large oscillations of process parameters and waste of time and resources in regulating process.To solve this control problem,the ADRC decoupling algorithm and the comprehensive decoupling algorithm(CDC)are adopted.Basd on simulations and experiments,the performance indexes of the two algorithms,such as stability,decoupling effect,anti-interference effect and performance robustness,are analyzed.The feasibilities of these methods in facility are verified.Secondly,for the whole control system of gas flow facility,the selecting control strategy is designed,which combines the PID control algorithm and the ADRC algorithm.The application range is expanded.The flexible switching between different flow and pressure points of the gas flow rig based on decoupling control is realized.Thirdly,for the gas flow facility with medium-pressure and closed-loop pipeline,the exhaust pressure control system of air compressor is identified and analyzed.Compared with the existing PI control algorithm,the superiority of ADRC algorithm is confirmed by the preliminary research.Based on the above work,a modification scheme for the whole control system of this facility is designed.