I have cascade control loop consists of 3 parameters
1-Boiler level
2-steam flow
3-water flow to compensate the decrease of the level in the boiler
The first loop is auto for the level of the boiler
The other loop is the water flow to compensate the decrease of the level
In cascade mode it take its set point from the steam flow+ the op of the control valve of the level
The main issue when converting the pid of the water flow to cascade some time it responds for 2-3 hours and then not responding
If we converted the loop to manual mode and give it op manual then convert again to cascade it will keep the same op
Then we observed to alarm at the pid from the network wind up status
And output wind up status was giving hi and lo
After decreasing the gain the windup became normal but the main issue still not solved

 

why are you using PID for your water flow control valve?

 

AI to DACA block for the reading of the flow meter and the PV of the flow meter became the input to the PID then the OP is the input for the AO
Do you have any other suggestions that may help?

 

PID designates the control action being taken. Suggest you read the manual for your controller function.

 

This sounds like "classic" boiler drum level control, and needs the ability to compensate for shrink and/or swell (classic boiler drum level control terminology). Most programmable controllers for this kind of application have "blocks" ready-made to insert in the control logic as it's pretty common when boilers are being controlled.

But this doesn't sound like a good application for PID control (though in the right hands it just might be depending on the application).

 

This sounds like "classic" boiler drum level control, and needs the ability to compensate for shrink and/or swell (classic boiler drum level control terminology). Most programmable controllers for this kind of application have "blocks" ready-made to insert in the control logic as it's pretty common when boilers are being controlled.

But this doesn't sound like a good application for PID control (though in the right hands it just might be depending on the application).

Yes itis incinerator and the design already implemented and it suppose to be working from 4 years
But now at startup itis working normal in manual or auto mode but not working in cascade
Do you have any suggestions?
Any idea to make it work as cascade ?
What block do you think will work better?

 

Block implemented as attached

 

I have no experience with Honeywell controllers; but I have encountered them on several occasions in various power plant applications with boilers (exhaust heat recovery boilers; auxiliary boilers; utility boilers; etc.), so I presume they have a boiler drum level control block--or they can recommend the best configuration of component blocks.

 

Ahmed,
Please explain what you think PID means.

 

Ahmed,
Please explain what you think PID means.

I already attached a photo for the PID block as Honeywell implemented it

 

what are the controller settings

 

Has this controller been in service for before? you noted 'startup' in your notes. Normally when working with PID function blocks in Experion controllers initialization will be handled automatically in many cases IF the control blocks used can pass initialization from the secondary (water) controller to the primary (level) controller when the water controller is in manual or auto. The Add.out parameter setting the water flow setpoint is typical of a math Add block. Math blocks cannot pass initialization back. The level controller does not know where to have its output when the water controller is put in cascade. A Reg control Summer block that adds the steam flow and the output of the level controller to provide an output to the setpoint of the water controller would be one way to set this up. Set up a test control module with a couple PID blocks and a reg control summer in between to see how the initialization to the primary would work as you switch secondary (water) controller mode in and out of cascade.