Is dual PID better or segmented control?
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The pressure vessel or tower is equipped with nitrogen supplementation and drainage systems, both of which have control valves. To regulate the pressure within the vessel or tower, it is possible to use hierarchical control based on pressure along with nitrogen supplementation and drainage functions, or to employ two separate PID controls. This dual-PID approach has not been used before; however, some people are now suggesting it. Do experts have any particular advantages to suggest for using this method? I always feel that this might lead to conflicts between the two PIDs; is such a possibility existing?
Either one is fine. 1. Split mode: There is a period between the discharge curve and the nitrogen replenishment curve during which neither valve operates; the controller calculates and determines when each valve should be activated based on the set pressure. Most design institutes are designed in stages. The advantage is that it is simple and clear. 2. By using two controllers, the same objective can also be achieved, with the pressure setpoint of the emission control controller being higher than that of the nitrogen make-up control controller. This setup allows for flexible control, and different PID parameters can be set for the two controllers, enabling different response speeds for emission control and nitrogen supplementation.
This post was last edited by Ku Liang Zhi Le on 2020-4-20 at 12:06. Two pressure single-loop control systems are set up; the same pressure parameter is sent to two controllers, which in turn control the nitrogen supplementation control valve and the discharge control valve. Because the operation of the nitrogen make-up valve affects pressure, and the operation of the discharge valve also affects pressure, the two pressure single-loop control systems are clearly interconnected in a significant manner; neither of these control systems can function properly ； A split-range control system involves detecting pressure and sending it to a pressure controller; the output from this controller is then sent to either a nitrogen supplementation control valve or an exhaust control valve. By setting appropriate split points, pressure can be controlled effectively ； If it is necessary to have two separate pressure control systems, the proportional gain of one controller can be set lower (making it less responsive), while that of the other controller can be set higher (making it more responsive). By adjusting the operating frequencies of the two systems, the correlation between them can be reduced, but it cannot be completely eliminated.