elements (static converters, machine, load, ... ), closely interacting. This work attempts to study such interactions considering harmonic disturbanc,es, and to determine, or build the best compUtation tools for analysis and further 'optimisation of the systems. The common solution consists inusing heavy simulation programs and spectra computation algorithms. But it is too time and memory consuming; it does not help much in understanding the phenomena, and the validity of the. results is questionable. That is why simplified models and optimised procedures must be looked for, to analyse the phenomena. Such anapproach implies the system to be civided in elements, using functionnal or physical criteria. Then the interactions to study must be defined, and consequently a model chosen for each of the elelements and,its environment. Finaly, the best calculation tool must be chosen. An harnonic analysis method, able to take into account mutual interactions between source, converter and machine is proposed. It provises a gread precision. It the case under study, it has been shown that the interactjons are not significant and that the global model can be simplified. The method is also applied to an example of electromagnetic compatibility. In this case, time and memory consumption are significantly reduced. The optimisation problem has not been faced yet, but this work presents a first step towards a generalised scheme for complex systems analysis, in a minimised computation volume..
