Concept and Application of PID Control and Implementation of Continuous PID Controller in Siemens PLCs

A multi-process pilot plant as a didactical tool for the teaching of industrial processes control in electrical engineering course

“…When students open or close it, they change the water flow rate from the upper to the lower reservoir, which impacts the level control system; When the group opens the solenoid valves that connect pipes to the upper and lower reservoirs, water flows to both reservoirs, and therefore, more power is required from pump no. 2 than when only the necessary solenoid valve is open; When the group opens the manual valve between the reservoirs and the two solenoid valves, the drive’s frequency at which the system remains stable almost reaches 43 Hz (maximum allowed for these drives is 66 Hz); After accomplishing the extra goal of the flow rate control project, the groups concluded that the appropriate gains are Kp (proportional) between 1.0 and 2.0, Ki (integral) between 40 and 50, and Kd (derivative) null or close to 0; For the level control system, Group 1 of the Wednesday classes could change the gains of the PID controller using Kp 1.0, Ki 30, and Kd 0.1; Groups that selected the PID control action could understand the role of each gain and observe the effects of testing different combinations, 15,23 which is a “trial-and-error” method for the controller tuning; Both level and flow system controllers are reverse-acting, i.e. when the measured process variable increases in comparison to the SP, the controller output decreases; In the level and flow rate control projects, the system response is faster than that of the temperature control project and the error in the ON–OFF control systems tends to be greater than that of PID control systems.…”

“…Groups that selected the PID control action could understand the role of each gain and observe the effects of testing different combinations, 15,23 which is a “trial-and-error” method for the controller tuning;…”

Implementation of Digital PID Controller in Siemens PLC S7-300

“…Integral term is proportional to the integral of the error. As it integrates the error over the time, it can lead to the overshoot of present value to the Set Point value [1,2,3,4,5].…”

The industrial control system cyber defence triage process

“…Based on this data the controller determines the necessary corrective action, represented as a Manipulated Variable (mv) that drives the behaviour of Final Control Elements such as a valve, that manipulate the mass or energy entering the process. Those control devices that act upon CV and provide logic to drive mv in the vulnerable process steps are deemed most critical [34].…”