文档介绍：ARTICLE IN PRESS
Control Engineering Practice 14 (2006) 1395–1412
ate/conengprac
Automatic detection and quantification of stiction in control valves$
. Shoukat Choudhurya, . Shaha,Ã, . Thornhillb, David S. Shookc
aDepartment of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G6
bDepartment of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
cMatrikon Inc., Suite 1800, 10405 Jasper Avenue, Edmonton, AB, Canada T5J 3N4
Received 11 September 2004; accepted 4 October 2005
Available online 1 December 2005
Abstract
Stiction is mon problem in spring-diaphragm type valves, which are widely used in the process industry. Although there have
been many attempts to understand and detect stiction in control valves, none of the current methods can simultaneously detect and
quantify stiction. Conventional invasive methods such as the valve travel test can easily detect stiction, but are expensive and tedious to
apply to hundreds of valves to detect stiction. Thus there is a clear need in the process industry for a non-invasive method that can not
only detect but also quantify stiction so that the valves that need repair or maintenance can be identified, isolated and repaired. This
work describes a model free method that can detect and quantify stiction that may be present in control valves using routine operating
data obtained from the process. No additional excitation or experimentation of the plant is required. Over a dozen industrial case studies
have demonstrated the wide applicability and practicality of this method as an useful diagnostic aid in control loop performance
monitoring.
r 2005 Elsevier Ltd. All rights reserved.
Keywords: Stiction; Stickband; Deadband; Hysteresis; Actuator; Control valve
1. Introduction control valve problems account for about one-third of the
32% of controllers classified as ‘poor’ or ‘fair’ in an
A typical chemical plant has hund