package TwoTankExample

connector ActSignal
Real act;
end ActSignal;

partial model BaseController
parameter Real K = 2;
parameter Real T(unit = "s") = 10;
ReadSignal cIn;
ActSignal cOut;
parameter Real ref;
Real error;
Real outCtr;
equation
cOut.act = outCtr;
error = ref - cIn.val;
end BaseController;

connector LiquidFlow
Real lflow(unit = "m3/s");
end LiquidFlow;

model LiquidSource
LiquidFlow qOut;
parameter Real flowLevel = 0.02;
equation
qOut.lflow = if time > 150 then 3*flowLevel else flowLevel;
end LiquidSource;

model PIcontinuousController
extends BaseController(T = 10, K = 2);
Real x;
equation
der(x) = error/T;
outCtr = K*(error + x);
end PIcontinuousController;

connector ReadSignal
Real val(unit = "m");
end ReadSignal;

model Tank
ReadSignal tSensor;
ActSignal tActuator;
LiquidFlow qIn;
LiquidFlow qOut;
parameter Real area(unit = "m2") = 0.5;
parameter Real flowGain(unit = "m2/s") = 0.05;
parameter Real minV = 0;
parameter Real maxV = 10;
Real h(start = 0.0, unit = "m");
equation
tSensor.val = h;
assert(minV >= 0, "minV - minimum Valve level must be  >= 0 ");
der(h) = (qIn.lflow - qOut.lflow)/area;
qOut.lflow = limitValue(minV, maxV, -flowGain*tActuator.act);
end Tank;

model TanksConnectedPI
LiquidSource source(flowLevel = 0.02);
Tank tank1(area = 1);
Tank tank2(area = 1.3);
PIcontinuousController piContinuous1(ref = 0.25);
PIcontinuousController piContinuous2(ref = 0.4);
equation
connect(tank2.tActuator,piContinuous2.cOut);
connect(tank1.tActuator,piContinuous1.cOut);
connect(tank1.tSensor,piContinuous1.cIn);
connect(tank1.qOut,tank2.qIn);
connect(tank2.tSensor,piContinuous2.cIn);
connect(source.qOut,tank1.qIn);
end TanksConnectedPI;

function limitValue
input Real pMin;
input Real pMax;
input Real p;
output Real pLim;
algorithm
pLim := if p > pMax then pMax else if p < pMin then pMin else p;
end limitValue;

end TwoTankExample;