SWMM - Control Rules - Modulated Controls

Modulated controls are control rules that provide a continuous degree of control applied to a Pump or flow regulator as determined by the value of some controller variable, such as the depth of water at a node or by time. The functional relationship between the control configuration and the controller variable can be specified using a control , a time series or a PID controller. Some examples of modulated control rules are:

 
RULE MC1
IF NODE N2 DEPTH >= 0
THEN WEIR W25 SETTING = CURVE C25

RULE MC2
IF SIMULATION TIME > 0
THEN PUMP P12 SETTING = TIMESERIES TS101

RULE MC3
IF LINK L33 FLOW <> 1.6
THEN ORIFICE O12 SETTING = PID 0.1 0.0 0.0 

Notice how a modified form of the action clause is used to specify the name of the control curve, time series, or PID parameter set that defines the degree of control. A set of PID parameters contains three values:

• proportional gain coefficient
• full time (in minutes)
• derivative time (in minutes)

Also, by convention, the controller variable used in a Control Curve or Controller PID will always be the object and attribute named in the last condition clause of the rule. As an example, in rule MC1 above, Curve C25 would define how the fractional fit in Weir W25 varied with water depth at Node N2. In rule MC3, the PID controller adjusts the opening height of Orifice O12 to maintain a flow rate of 1.6 on Link L33.

See also: SWMM Rules Controls