WasteWater.Misc

Information

This package provides a collection of "conrollers" that are needed for the
complex wastewater treatment plant example.

Main Author:
 
          Gerald Reichl
          Technische Universitaet Ilmenau
          Faculty of Informatics and Automation
          Department Dynamics and Simulation of ecological Systems
          P.O. Box 10 05 65
          98684 Ilmenau
          Germany
          email: gerald.reichl@tu-ilmenau.de

 
Copyright (C) 2000 - 2003, Gerald Reichl

The Modelica package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying disclaimer in the documentation of package Modelica in file "Modelica/package.mo".

WasteWater.Misc.TwoPoint

Information

This is an on-off (two-point) controller with hysteresis.
The hysteresis is the difference beetween the parameter on and off.
When the input signal exceeds the "on" value, the output signal
is "out_on" and when the input signal drops below the
"off" value, the output signal is "out_off".

Parameters

Name	Default	Description
on	1.0
off	0.0
out_on	1.0
out_off	0.0

Modelica definition

model TwoPoint "On-Off controller with hysteresis" 
  //Two-point controller 
  parameter Real on=1.0;
  parameter Real off=0.0;
  parameter Real out_on=1.0;
  parameter Real out_off=0.0;
  Boolean mode;
  Modelica.Blocks.Interfaces.InPort e(final n=1);
  Modelica.Blocks.Interfaces.OutPort u(final n=1);
algorithm 
  // 0: Controller is off
  // 1: Controller is on
  
  when initial() then
    mode := if e.signal[1] >= on then true else false;
  end when;
  
  when e.signal[1] >= on and mode == false then
    mode := true;
  end when;
  
  when e.signal[1] <= off and mode == true then
    mode := false;
  end when;
  
  u.signal[1] := if mode == true then out_on else out_off;
end TwoPoint;

WasteWater.Misc.ReturnController

Information

Input signal is a flow measurement.
Output is a control signal between -1 and 1.

This component is only used for the complex plant example.
Therefore no further documentation.

Parameters

Name	Default	Description
Qmin	500	minimal allowed return acticated sludge (RAS) flow [m3/h]
Qdry	1200	flow until dry weather is assumed [m3/h]
Qrain	1500	maximum RAS flow during rain situation [m3/h]
Qmax	2520	maximum flow the treatment plant can handle [m3/h]
RAS_ratio	120	RAS/Inflow ratio during dry weather [%]

Modelica definition

model ReturnController "Return Sludge Controller" 
  
  parameter Real Qmin=500 "Minimum RAS flow [m3/h]";
  parameter Real Qdry=1200 
    "Dry weather inflow until RAS is ratio dependent [m3/h]";
  parameter Real Qrain=1500 "Maximum RAS flow during rain situation [m3/h]";
  parameter Real Qmax=2520 "Maximum wastewater flow to WWTP [m3/h]";
  parameter Real RAS_ratio=120 "RAS/Inflow ratio [%]";
  
  Real u1;
  Real u2;
  Real u3;
  
  Modelica.Blocks.Interfaces.InPort in1(final n=1);
  Modelica.Blocks.Interfaces.OutPort out(final n=1);
equation 
  
  u1 = Qmin;
  u2 = in1.signal[1]/24*RAS_ratio/100;
  u3 = Qdry*RAS_ratio/100 + (Qrain - Qdry*RAS_ratio/100)/(Qmax - Qdry)*(in1.
    signal[1]/24 - Qdry);
  
  out.signal[1] = 2*min(max(u1, u2), u3)/Qmax - 1;
  
end ReturnController;

WasteWater.Misc.RecycleController1

Information

Input signal is a nitrate measurement,
output is a control signal between -1 and 1
and is calculated in two discrete steps between NO3max
and NO3min.

This component is only used for the complex plant example.
Therefore no further documentation.

Parameters

Name	Default	Description
NO3max	2.0	[mg/l]
NO3min	1.0	[mg/l]
Pref	70	Reference pumppower between NO3max and NO3min [%]
dNO3max	30	Reduction of the ref. pumppower at NO3-max by x [%]
dNO3min	30	Increase of the ref. pumppower at NO3-min by x [%]

Modelica definition

model RecycleController1 "Recycle Sludge Controller1" 
  
  parameter Real NO3max=2.0 "[mg/l]";
  parameter Real NO3min=1.0 "[mg/l]";
  parameter Real Pref=70 "Reference pumppower between NO3max and NO3min [%]";
  parameter Real dNO3max=30 "Reduction of the ref. pumppower at
  NO3-max by x [%]";
  parameter Real dNO3min=30 "Increase of the ref. pumppower at NO3-min
  by x [%]";
  
  Real u1;
  Real u2;
  Real u3;
  
  Modelica.Blocks.Interfaces.InPort in1(final n=1);
  Modelica.Blocks.Interfaces.OutPort out(final n=1);
equation 
  
  //red = Pp*dNO3max/100;
  //[%]
  //inc = Pp*dNO3min/100;
  //[%]
  u1 = 2*(Pref + dNO3min)/100 - 1;
  u2 = 2*Pref/100 - 1;
  u3 = 2*(Pref - dNO3max)/100 - 1;
  out.signal[1] = if in1.signal[1] < NO3min then u1 else if in1.signal[1] < 
    NO3max then u2 else u3;
  
end RecycleController1;

WasteWater.Misc.RecycleController2

Information

Input signal is a Nitrate measurement
Output is a control signal between -1 and 1
and is linear interpolated between NO3min and NO3 max.

This component is only used for the complex plant example.
Therefore no further documentation.

Parameters

Name	Default	Description
NO3max	2.0	[mg/l]
NO3min	1.0	[mg/l]
Pref	70	Reference pumppower between NO3max and NO3min [%]
dNO3max	30	Reduction of the ref. pumppower at NO3-max by x [%]
dNO3min	30	Increase of the ref. pumppower at NO3-min by x [%]

Modelica definition

model RecycleController2 "Recycle Sludge Controller2" 
  
  parameter Real NO3max=2.0 "[mg/l]";
  parameter Real NO3min=1.0 "[mg/l]";
  parameter Real Pref=70 "Reference pumppower between NO3max and NO3min [%]";
  parameter Real dNO3max=30 "Reduction of the ref. pumppower at
  NO3-max by x [%]";
  parameter Real dNO3min=30 "Increase of the ref. pumppower at NO3-min
  by x [%]";
  
  Real u1;
  Real u2;
  Real u3;
  Modelica.Blocks.Interfaces.InPort in1(final n=1);
  Modelica.Blocks.Interfaces.OutPort out(final n=1);
equation 
  
  //red = Pp*dNO3max/100;
  //[%]
  //inc = Pp*dNO3min/100;
  //[%]
  u1 = 2*(Pref + dNO3min)/100 - 1;
  //u2 = 2*Pref/100 - 1;
  u2 = 2*((Pref + dNO3min)/100 - ((dNO3max + dNO3min)/100)/(NO3max - NO3min)*(
    in1.signal[1] - NO3min)) - 1;
  u3 = 2*(Pref - dNO3max)/100 - 1;
  out.signal[1] = if in1.signal[1] < NO3min then u1 else if in1.signal[1] < 
    NO3max then u2 else u3;
  
end RecycleController2;