mechanizator
Member
Dear all
I would like to ask you for help in solving one algorithm, because I never worked with cascade PID.
I have to realize heating valve control basing on 2 temperatures. It look like:
there's main bath tank, heat exchanger, 2 temperature probes and modulating valve.
Temperature TT2 and modulating valve are placed on entry hot water circuit that heats up exchanger. Temperature TT1 is placed on exit circuit from heat exchanger and it's showing real temperature of the water that goes to bath tank.
Operator can change setpoint of bath temperature and change also treshold for deltaT. DeltaT is calculated as temp difference: DeltaT=(T2-T1).
If treshold set > DeltaT it closes the modulating valve and it's opening back when deltaT goes below the treshold set. In theory I should use main PID to calculate difference between temperature T1 and bath temperature setpoint but I don't know how to parametrize the slave PID that will calculate the right output for valve basing on both temperatures difference.
Thank you for your help
Kind regards
I would like to ask you for help in solving one algorithm, because I never worked with cascade PID.
I have to realize heating valve control basing on 2 temperatures. It look like:
there's main bath tank, heat exchanger, 2 temperature probes and modulating valve.
Temperature TT2 and modulating valve are placed on entry hot water circuit that heats up exchanger. Temperature TT1 is placed on exit circuit from heat exchanger and it's showing real temperature of the water that goes to bath tank.
Operator can change setpoint of bath temperature and change also treshold for deltaT. DeltaT is calculated as temp difference: DeltaT=(T2-T1).
If treshold set > DeltaT it closes the modulating valve and it's opening back when deltaT goes below the treshold set. In theory I should use main PID to calculate difference between temperature T1 and bath temperature setpoint but I don't know how to parametrize the slave PID that will calculate the right output for valve basing on both temperatures difference.
Thank you for your help
Kind regards