Proportional-Integral Controller for Water Level


The input file Level-Base.inp models a standpipe with forced liquid inflow at 14 m/s, and a drain with velocity driven by the height of water above.  Run the problem and plot the water level to convince yourself that it has achieved a steady state.  Make a hw6 directory, and copy the file trcdmp to it with the name "BaseDump".  If jEdit is able to submit TRACE jobs for you open Level-Step.inp, and use the SNAP plugin to execute the deck.  When the execution monitor's "Submit Calculation" window appears, fill in the "Restart File" box with the full path to your "BaseDump" file. If this capability is not available, follow the instructions in class to run TRACE from a Bash shell (typed commands).  Plot the results. Based on the plot select either the Cohen and Koon or Ziegler-Nichols method, and use what you learned from the lecture on control theory to set the gain and integration time scale on a PI controller that will drive the level to 7.5m.  I've provided you with templates for both proportional and PI controllers that start from "BaseDump".

Show all and explain all results relevant to selection of the initial gain and integration time scale for the PI controller.  Once you have these values, make four more runs with base gain and integration time multiplied and divided by 2.  Plot level vs. time from 0 to 100 seconds for all five of these runs . Select the result that drives the water level to within 0.01m of 7.5m in the least amount of time (show any detailed plots you need to make this selection).  If it is not the original, make one more study on the variation (half and double) of parameters from the previous run with best results.  This will give you three more curves of level vs. time to plot in addition to your previous best.  Again document your selection of best parameters.



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