Requirement
Following the commissioning of the all electric ship’s power station, a phenomenon active power “pumping” (of several MW) between 2 diesel generators has been observed. This phenomenon is characterised by active power transfer in both ways from one diesel generator to another; and is likely to cause a malfunction of the control system as well as an accelerated deterioration of the diesel generators themselves. The network operator wishes to identify the causes of this issue and to solve this problem.
Realization
An investigation was carried out in order to identify, with the technical direction of the client, the probable causes of the power “pumping” (malfunctioning injector, blocked air filters, incorrect settings of speed regulators, etc...).
The following assumptions were simulated in order to recreate this active power “pumping”.
As per CAPSIM’s suggestion, the IEEE typical excitation system of the generators was replaced by a more detailed and complex one. This allowed showing a non-linearity of the excitation system leading to an amplification of the natural pulsation torque of the Diesel generator linked to the pistons strokes.
A modification of the excitation system parameters (validated by simulation) made the non-linearity to disappear and hence to solve the problem.
Results
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).
