Control of high-order processes: repeated-pole plus dead-time models' identification

Abstract

This paper aims to present two approaches for repeated-pole plus dead-time (RPPDT) models identification procedures for highorder processes based. First approach is based on using two or three points over the process reaction curve −an open-loop test− whereas the second approach is based on the use of the process relay control oscillating signals −a closed-loop test. Equations are provided for both model parameters identification as well as order estimation. Comparison tests confirm that the RPPDT models provide a better representation of the high-order process dynamics than its simple, usually employed, first-order approximation. These models are suitable for process representation in dynamic simulations and control system design studies.

Keywords:

• High-order processes
• model identification
• repeated-pole plus dead-time models
• step-test response
• relay-feedback test

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 https://github.com/JuliaNLSolvers/LsqFit.jl

2 For processes with positive gain K.

3 Control system simulation and optimisation is conducted using the JModelica.org environment.

Additional information

Funding

This research was supported by the Catalan Government under Project 2017 SGR 1202 and the Spanish Government through the MICINN project (PID2019-105434RB-C33).