* Diagnosis of Fluid Systems utilizing Gröbner Bases and
  Filtering of Consistency Relations
* Jonas Biteus
* Reg nr: LiTH-ISY-EX-3237
* 23rd October 2001

Abstract

The objective of this master's thesis is to develop a method 
for automatic design of diagnostic systems for pulp and paper 
industry. General models for fluid systems are presented. The 
models simulate slow dynamics based on object-oriented sub-
models. The sub-models are tanks, pipes, control valves, 
pumps, mixers and dividers. The diagnostic systems are based 
on hypothesis tests and decision structures. The hypothesis 
tests are formed as tests with thresholds. The tests are con-
structed as normalized residuals. Consistency relations are 
used to construct the residuals. The consistency relations 
are extracted from model equations. Through calculations of 
Gröbner bases, good decision structures are achieved.

To evaluate the methods, they are applied to a stock pre-
paration and broke treatment system from a paper mill. Three 
different simulations including three different faults are 
presented. A semi-automatic algorithm, with the ability to 
construct diagnostic systems for arbitrary fluid systems, is 
presented. The diagnostic system, constructed with the semi-
automatic algorithm, can detect and isolate faults. Arbitrary 
slow dynamic faults can be detected and isolated.