The flow characteristics of the control valve cannot be ignored. The flow characteristics of the control valve are too steep. As long as the adjusted amount has a small deviation, the adjusted medium will have a greater change. Even if the controller has a very small output, due to the valve, the medium flow will change greatly, which will cause over-adjustment and cause constant amplitude oscillation in the entire system. For the above situations, if the characteristics of the valve cannot be modified, the proportional gain of the controller can be reduced to improve the control quality.
