Active disturbance rejection control for closed-loop gas flow facilities

Gas flow facilities are essential to test gas flow sensors, meters and other devices. Pressure control is a key problem in particular for high pressure gas flow facilities. An appropriate control scheme is critical to improve the stability and the speed of the pressure control. This paper presents a linear Active Disturbance Rejection Control (ADRC) scheme for high pressure gas flow facilities with closed-loop pipelines. The control model of the flow facility is identified by a step response method. A reduced-order linear expansion state observer and a related control law are designed to estimate and compensate the total disturbance of the system. The robustness of the ADRC algorithm is compared with a PID control algorithm by Monte Carlo simulation. Control speed and disturbance rejection ability of ADRC are also compared with PID through simulation and gas flow experiments. The results show that, compared with PID, ADRC has a shorter settling time, stronger disturbance rejecting capability and more robust performance. The improved pressure stability has been proved to be beneficial to test gas flow sensors in the facility.