Control loop performance monitoring in chemical control applications

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Sähkötekniikan korkeakoulu | Master's thesis
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Date

2024-05-20

Department

Major/Subject

Control, Robotics and Autonomous Systems

Mcode

ELEC3025

Degree programme

AEE - Master’s Programme in Automation and Electrical Engineering (TS2013)

Language

en

Pages

90

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Abstract

Water treatment is an important process to meet the water-quality requirements based on the usage purpose. The processes are controlled through a control loop. To achieve water that meets the requirements, it is important that the control loop should perform satisfactorily. Control loop performance monitoring (CPM) has brought much attention in the process industry to recognize poorly performing control loops. Because of this, numerous CPM indices have been developed based on process needs. These include Harris index, integral-based indices and LQG evaluation index, among others. In this thesis, the control loop performance is monitored in four control loops in different water treatment processes. CPM is achieved by calculating the Integral of Absolute Error (IAE), Integral of Square Time derivative of the Control input (ISTC), and the average time between two zero-crossings. The indices are modified and combined according to the process needs and findings, resulting in a combined performance index. The combined performance index showed that it describes closely the control loop performance, which makes it an effective tool for CPM. This index will be useful to determine the control loop performance status in the particular control loops. Based on the results, the combined performance index can be used in complex processes with long delays. This thesis recommends that the combined performance index is utilized to evaluate a particular control loop.

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Supervisor

Corona, Francesco

Thesis advisor

Tikkala, Vesa-Matti

Keywords

control loop performance monitoring, control loop performance assessment, wastewater treatment, WWTP, raw water treatment

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https://urn.fi/URN:NBN:fi:aalto-202405263665

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