In this work, an artificial neural network (ANN) based framework for fault
diagnosis in batch chemical plants is presented. The proposed FDS consists
of an ANN structure supplemented with a knowledge based expert system (KBES
) in a block-oriented configuration. The system combines the adaptive learn
ing diagnostic procedure of the ANN and the transparent deep knowledge repr
esentation of the KBES. The information needed to implement the FDS include
s a historical database of past batches, a hazard and operability (HAZOP) a
nalysis and a model of the batch plant. The historical database that includ
es information related to normal and abnormal operating conditions is used
to train the ANN structure. The deviations of the on-line measurements from
a reference profile are processed by a multi-scale wavelet in order to det
ermine the singularities of the transients and to reduce the dimensionality
of the data. The processed signals are the inputs of an ANN. The ANNs outp
uts are the signals of the different suspected faults. The HAZOP analysis i
s useful to build the process deep knowledge base (KB) of the plant. This b
ase relies on the knowledge of the operators and engineers about the proces
s and allows the formulation of artificial intelligence algorithms. The cas
e study corresponds to a batch reactor. The FDS performance is demonstrated
through the simulation of different process faults. The FDS proposed is al
so compared with other approaches based on multi-way principal component an
alysis. (C) 2000 Elsevier Science Ltd. All rights reserved.