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Expertise regarding diesel generator fed complex systems

You can contact the CAPSIM's specialist of this activity:
   - By email
   - By phone: +33 (0)4 42 63 61 18

Soon after the commissioning of a 3MVA diesel generator on a site, degradations and tears were noticed in the mechanical coupling between the diesel engine and the alternator. The expert checking on the mechanical coupling did not show any fault on the deteriorations.
The network manager therefore requested CAPSIM to do a diagnostic based on numerical simulations.

Capsim did a modelling of the diesel engine, the alternator and the mechanical coupling in order to create a virtual test bench allowing the observation of constraints faced by the coupling in the various exploitation phases.
Several assumptions were considered and then simulated in agreement with the technical direction:
  • Constraints belonging to the electrical network
    • Load acceptances in normal and other degraded conditions,
    • Load pulsation,
    • Transformer energisation,
    • ...
  • Constraints belonging to the diesel engine
    • Loss of a cylinder (injector blocked or clogged air filter), ,
    • Speed regulator pumping,
    • Faulty turbo system,
    • ...,

Finally, the simulations allowed identifying the problem. It was actually the over speed protection that activated in the end phase of the diesel engine start which, associated with the specific inertia of the alternator, caused a torque shear which was beyond the actual capacity of the mechanical coupling.

The use of these complex multi-physical system modelling helped to create a virtual (or numerical) test bench on which all tests regarding the variation of characteristics are possible and all of the instrumental variables are without risk for the installation.

The use of this virtual test bench enabled showing and quantifying various phenomena. It also helped verify the relevance of the recommended solutions (solving of the issue and hence no perturbation of the system behaviour).

Thanks to this study, a modification of the Diesel over-speed management strategies was brought forward by the Diesel manufacturer.

CAPSIM - 11 Boulevard de la Grande Thumine - Parc d'Ariane, Batiment E1 - 13090 Aix-en-Provence - France
Tel : +33 (0)4 42 63 61 18