Creating RTC controls in MIKE+ can help the modeller to simulate unconventional situations and user specified operational schemes - as for instance, a pump working on an hourly schedule regardless of any level sensors (i.e., as wet well level). The control functions in RTC work on a Boolean logic and under TRUE conditions, it goes to the next condition and so on until complete. In this example, a pump working from 16:00 hrs. and shuts down at 20:00 hrs. is demonstrated.
This operation includes the following steps:
#01 - Set the pump operation conditions - see Fig. 1.
A series of conditions and two actions (ON //OFF) can do the job. The variable Hour(SimulationTime()) allows the user to select a time of the day to operate a control. The conditions discretized below are the time before pump start (time before 16:00 HRS), time at pump start until pump stop time (time at 20:00 HRS) and the time after the pump should have stopped.
Fig. 1 - Discretized operation conditions of the pump
#02 - Set up the actions to be performed by the controlled structures - see Fig. 2.
For this purpose, two actions are sufficient to perform the desired operational scheme. One to start the pump and another one to Stop the pump.
Fig. 2 - Controlled Structure Actions in MIKE+
#03 - Run the simulation and check the results - see Fig. 3.
Under these conditions the pump discharge follows this flow pattern:
Fig. 3 - Scheduled pump discharge in MIKE+
#04 - Other options to set up the conditions
There are other options to write these conditions in a more effective way, for example running the pump between 16:00 and 20:00 hrs.
Hour( SimTime() ) > 16 && Hour( SimTime() ) < 20
The user can be more specific and define a timer to the minute:
TimeOfDay ( SimTime () ) > #+16:25:00# && TimeOfDay ( SimTime () ) < #+20:35:00#
As an example, the set of conditions can be simplified as follows:
Fig. 4 - Set up control conditions in MIKE+
#05 - ACTION Using the same action option of ON and OFF – see Fig. 5.
Fig. 5 - Controlled Structure Actions in MIKE+
#06 - This will result in a pump working on a specific hourly schedule - see Fig. 6.
The discharge of the pump is controlled under a daily schedule.
Fig. 6 - Pump discharge in MIKE+
The pump can be controlled to discharge on a daily schedule using the function variable Hour(SimulationTime(). This will allow the use of time as the control physical variable instead of the most commonly used sensor water level.
FURTHER INFORMATION & USEFUL LINKS
MIKEPlus Release Notes