15. Handy Instruction Design Examples Step 2: From the figure, we can see that when K P = 40, there will be over-reaction, so we will not select it. When K P = 20, the PV reaction curve will be close to SV and there will not be over-reaction, but due to its fast start-up with big transient MV, we will value more smoothly, so we will use it. Finally when K P = 5, we will not consider it consider to put it aside. When K P = 10, the PV reaction curve will get close to SV due to the slow reaction. Step 3: Select K P = 10 and adjust K I from small to big (e.g. 1, 2, 4 to 8). K I should not be bigger than K P . Adjust K D from small to big (e.g. 0.01, 0.05, 0.1 and 0.2).
K D should not exceed 10% of K P . Finally we obtain the figure of PV and SV below. 1.5 PV=SV 1 0.5 K =10,K =8,K =0.2 P I D 00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Time (sec) Note: This example is only for your reference. Please adjust your parameters to proper ones according to your actual condition of the control system. z In the temperature control environment, Delta PLC provides auto-tuning on parameters of PID instruction, so users can get good control results without parameter adjusting steps . See below for the auto-tuning process in this example: 1. Initial adjustment. Operate the most suitable parameter for PID temperature control and store the result in D200~D219.
See the reaction curve below: Auto tuning area S +4 = K3 PID control area S +4 = k4 3 3 DVP-PLC Application Examples 15-24