Forecasting

How you can use a Forecasting Model in your control system.

Forecasting models are ideal for predicting what a certain process value should be given all other relevant process information. This can give an operator peace of mind when they are second guessing a value they are seeing, and it can give an instrument technician more flexibility when they need to work on a critical piece of equipment.

Typical Use Cases

When implementing a forecasting model into your control system, you will need to determine what you would like to accomplish with this predicted value. Here we will go over typical PLC or DCS use cases:

Creating a “Soft Sensor” with a deviation alarm

The prediction from the forecasting model is typically brought in as a “soft” point and displayed on the HMI near the actual device’s readout. This is ofter accompanied by a deviation alarm to visually show the operator when the predicted value has strayed from the real world value.

Using the prediction for control

Sometimes you may want to allow the prediction to be fed into a PID controller. If the typical transmitter or sensor is experiencing issues, the operator may wish to control using the predicted value while the technician works to repair or test the device. The below diagram shows a simple application for adding a value selector that swaps between I/O and the prediction.