A cycle-based and multirate approach for power system simulation application to the ageing estimation of a supercapacitor-based ferry

- Cycle-based formulation for the simulation of power systems.
- Multi-physical modelling of energy storage device.
- Ageing behaviour simulation of supercapacitor throughout a lifetime of several years of operation.
- Integration of a multi-rate simulation method based on variable step solver.

This paper presents a general multi-rate method for the simulation of power systems with a wide range of time scales and with high mutual dependency between the fast and slow state variables. The original concept developed in this work relies on a cycle-based problem formulation, which consists in finding the repeating operation sequences of the system, at the different time scales. Next, a discrete form version of a conventional second order variable step solver is proposed and allows the extrapolation of the results beyond a large number of cycles, while maintaining and controlling a predetermined error tolerance on the state variables. This cycle-based formulation is applied to the ageing behaviour simulation of the energy storage unit of an all-electric ferry which only uses supercapacitors as energy storage. This problem needs the simulation of the electrical power operation of the boat, throughout its lifetime of 20 years. With this original cycle-based formulation, the computation effort can be reduced by several hundreds while maintaining low error tolerances.