I would like to ask what a PID controller means in Aspen dynamic simulation

PID (Proportional-Integral-Derivative) controller is a proportional-integral-derivative control device. It is one of the most fundamental controllers widely used in the industrial sector, whose main function is to output corrections proportionally based on the deviation value. P refers to a popular linear control strategy ； I represents integral control, whose main function is to output corrections based on the integral of the deviation value in order to eliminate that deviation ； D denotes derivative control, whose main function is to enable direction correction \"in advance\". To achieve the desired level of control performance, it is necessary to adjust the three parameters such as PID in various situations such as process variations; this process is known as PID parameter tuning. 　　In a PID controller, the error signal (the difference between the temperature desired by the controlled system and the actual temperature) is amplified in three ways—proportional, integral, and derivative—before being applied to the temperature control power supply circuit. The proportional gain provides an instantaneous response to the error signal. The integral gain calculates the integral of the error signal, reducing the error to a level close to zero. Integral gain also helps to filter out noise in the measured temperature signal. The differential gain makes the drive dependent on the rate of change of the measured temperature; proper use of differential gain can reduce the stabilization time required when the response position changes or due to other disturbances. However, in many cases, the proportional-integral (PI: Proportional-Integral, without derivative gain) control strategy can also produce results that meet the requirements, and it is usually easier to adjust it to a stable operating state and achieve a satisfactory settling time compared to a full PID controller.

Thank you, moderator! You’re really great, haha

PID is an abbreviation for Proportional, Integral, and Derivative. The proportional control mechanism responds in proportion to the deviation of the system; as soon as a deviation occurs, proportional control takes action to reduce that deviation. A large proportional gain can speed up regulation and reduce errors, but an excessively high proportional gain reduces the stability of the system, and may even lead to its instability. Integral control function: It enables the system to eliminate steady-state error and improve accuracy. Due to errors, integral control is applied until no error remains, at which point the integral control stops and an constant value is output by it. The strength of the integration effect depends on the integration time constant Ti; the smaller Ti is, the stronger the integration effect. Conversely, a larger Ti value results in a weaker integrating effect; the addition of integral control can reduce system stability and slow down the dynamic response. Integral action is often combined with the other two control laws to form a PI controller or a PID controller. Differential regulating effect: The differential action reflects the rate of change of the system’s deviation signal; it has predictive capabilities, allowing it to anticipate the trend in deviation changes. As a result, it enables preemptive control, eliminating the deviation before it even arises. Therefore, the dynamic performance of the system can be improved. By selecting an appropriate differential time, overshoot can be reduced, as well as the settling time. Differential action amplifies noise interference; therefore, excessive differential adjustment is detrimental to the system’s resistance to interference. Furthermore, a differential reaction deals with the rate of change, and when there is no change in the input, the output of the differential operation is zero. Differential action cannot be used alone; it needs to be combined with the other two control mechanisms to form PD or PID controllers.

:) Advanced control usually opts for PID control, right?

It is the PID controller used in conventional DCS control; all modern advanced control methods are based on PID control.