Civil Engineering Reference
In-Depth Information
Input
Output
T2
Resc
PID
T1
Set-point
Resc
V-1
PID
T3
SUM
Resc
PID
V-2
H3
T4
Resc
AXB
PID
NEG
Damper
H4
Enthalpy
(0 or 1)
COM
Enthalpy
Figure 8.14
Example of CAV control strategy implemented in a symbolic program-
ming environment.
Table 8.2
Function routines used in the control program listed in Table 8.1
FUNCTION RSCLFR(E,F,G)
C Rescale from 0-100 to E-F
RSCLFR=E+G*(F-E)/100.0
IF (E.LT.F) THEN
RSCLFR=MIN(F,MAX(E,RSCLFR))
ELSE
RSCLFR=MIN(E,MAX(F,RSCLFR))
ENDIF
RETURN
END
FUNCTION RSCLTO(E,F,G)
C Rescale to 0-100 from E-F
RSCLTO=100.0*(G-E)/(F-E)
RSCLTO=MIN(100.0,MAX(0.0,RSCLTO))
RETURN
END
split-range control (excluding outdoor air flow control), the room temperature
control and humidity control in a simplified symbolic programming environ-
ment for BAS stations is shown in Figure 8.14. An implementation of the
same strategy in a high-level-language programming environment is shown
in Table 8.1, where the Fortran language format is used. The PID function
presented in Table 7.4 is used. The function routines used, except the func-
tion for enthalpy calculation, are listed in Table 8.2. It is worth noting that
the programs presented here might have some stability problems due to the
interference of different PID functions and in the transient regions between
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