A5.4 Pid Computation Details; A5.4.1 Proportional Derivative Leading Type Pid Control Algorithm (I-Pd) - YOKOGAWA Admag TI Series User Manual

Parameter
Index
Name
61 HI_ALM
62 LO_ALM
63 LO_LO_ALM
64 DV_HI_ALM
65 DV_LO_ALM
A5.4 PID Computation Details
As the PID calculation method, the I-PD method (PI-D method for some modes) is employed.
A5.4.1 Proportional Derivative Leading Type PID Control
Algorithm (I-PD)
The proportional derivative leading type PID control algorithm (I-PD) ensures control stability
against sudden changes in the setpoint, such as when the user enters a new setpoint value. At
the same time, the I-PD algorithm ensures excellent controllability by performing proportional,
integral, and derivative control actions in response to changes of characteristics in the controlled
process, changes in load, and occurrences of disturbances. If the mode of the PID block is Auto
and RCas, calculation is done with this I-PD method. When the mode of the block is Cas, the
proportional derivative leading type PID control algorithm is employed in order to obtain better
performance against the changes in the setpoint. The control algorithm is automatically switched
by the block in accordance with the mode.
The basic form of each algorithm is expressed in the equation below.
比例微分先行形PID （I-PD方式）
{
ΔMVn＝K ΔPVn+
微分先行形PID （PI-D方式）
{
ΔMVn＝K Δ(PVn－SPn)+
ΔMVn : change in control output
ΔPVn : change in measured (controlled) value ΔPVn=PVn- PVn-1
ΔT : control period (Block Header.period_of_execution)
K : proportional gain (GAIN)
Ti :i ntegral time (RESET)
Td : derivative time (RATE)
The subscripts, n and n-1, represent the time of sampling such that PVn and PVn-1 denote the
PV value sampled most recently and the PV value sampled at the preceding control period,
respectively.
Default Write
Value mode
--- ---
--- ---
--- ---
--- ---
--- ---
ΔT Td
(PVn－SPn)+ Δ(ΔPVn)
Ti ΔT
ΔT
(PVn－SPn)+
Ti
<Appendix 5. PID Block>
Valid
Range
Same as HI_HI_ALM.
Same as HI_HI_ALM.
Cleared when the PV value increases
above LO_LIM + ALM_HYS.
Same as LO_ALM.
Alarm that is generated when the value of
(PV - SP) has exceeded the DV_HI_LIM
value. Other features are the same as
HI_HI_ALM.
Alarm that is generated when the value of
(PV - SP) decreases below the DV_LO_LIM
value. Other features are the same as
LO_LO_ALM.
}
}
Td
Δ(ΔPVn)
ΔT
282
Description
IM 01E21A02-03EN