770 likes | 3.11k Views
Course PEF3006 Process Control Fall 2018. Feedforward Control. By Finn Aakre Haugen (finn.haugen@hit.no). Why feedforward control? Faster disturbance compensation and/or Faster setpoint tracking (important only with time-varying setpoint ).
E N D
Course PEF3006 Process ControlFall 2018 Feedforward Control By Finn Aakre Haugen (finn.haugen@hit.no) PEF3006 Process Control. USN. F. Haugen. 2018
Why feedforward control? • Faster disturbance compensation • and/or • Faster setpoint tracking (important only with time-varying setpoint) PEF3006 Process Control. USN. F. Haugen. 2018
Control system with bothfeedforward and feedback: PEF3006 Process Control. USN. F. Haugen. 2018
Example 1: Feedforward in level control system Simulator Let's derive the feedforward controller (it is quite easy). Skala: LTLine brukerforum, 9.1.18: Minikurs i regtek. F. Haugen.
Example 2:Feedforward control in a temperature control system • (Wewill run a simulator ofthisexample.) PEF3006 Process Control. USN. F. Haugen. 2018
Example cont.: How to derive the feedforward controller: (1) Process modelling: Energy balance: (2) The feedforward controller is obtained bysolving for the control variable, andsubstituting the process variable by its setpoint: Can it be implemented? Find out by inspecting the right-hand side! All terms must have known values. Which sensors are needed? PEF3006 Process Control. USN. F. Haugen. 2018
Example cont.: • Simulator: • Feedforward control in temperature control system PEF3006 Process Control. USN. F. Haugen. 2018
Example 3:Feedforward in a DP system( dynamic positioning) 8 • Simulator: • Feedforward in DP system PEF3006 Process Control. USN. F. Haugen. 2018
9 Experimental feedforward PEF3006 Process Control. USN. F. Haugen. 2018
10 Structure of control system: PEF3006 Process Control. USN. F. Haugen. 2018
11 Relation between disturbance measurement and steady-state control signal (with PID controller): PEF3006 Process Control. USN. F. Haugen. 2018
Example 1: Temperature control of air heater 12 PEF3006 Process Control. USN. F. Haugen. 2018
Example 1 cont. 13 Potensio- meter Pot.metervoltage Air flow (fan speed) Temp at outlet PEF3006 Process Control. USN. F. Haugen. 2018
Without feedforward (only feedback): 14 PEF3006 Process Control. USN. F. Haugen. 2018
With feedforward (and feedback) 15 Improvement? PEF3006 Process Control. USN. F. Haugen. 2018
Example 2: Feedforward from inlet temperatur (Tp_inn)in temp. control of heat ex. • Simulator PEF3006 Process Control. USN. F. Haugen. 2018