Anti-Windup PID Control for Globe Valve Internal Disturbances: Design and Simulation Approach

Internal disturbances of a working globe valves come in three variants. The variants are the breakaway point, the stuck point, and the moving friction point. The breakaway point is the point where the fluid is just about to be free after being stuck for some period within the medium. This point comes with excessive friction and it is expected that the globe valve should be able to withstand this excessive friction. At stuck point, initial movement of fluid is practically stalled due to friction which should not be allowed to prolong to prevent damage of the globe valve. The moving friction point is the normal operational point friction of the globe valve when handling fluid movement. In practice, these disturbances transition from one point to another sequentially making them seem combined because of the fast rate at which they transition. In order to solve these problems, the natures of these disturbances are modeled mathematically and simulated using SIMULINK. Then, Anti-windup Proportional Integral Derivative controller (AW-PID) is introduced to control the operation of the globe valve to overcome the saturation effect associated with actuators which the conventional PID controller could not handle effectively. For a medium without the disturbances, AW-PID gives an overshoot of 1.40%, rise time of 0.015s for a unit step input function at 0.0042s settling time. For a fully working globe valve, an overshoot of 7.25% is obtained for a unit step input function with a rise time of 0.133s and a settling time of 0.536s. This work presents an improved technique to handle the internal disturbances of a working globe valve.