Benchmarking of model-based systems engineering tools for the performance assessment of marine energy systems
van Vugt, J.
The purpose of this paper is to highlight the stages where standardization is needed for model-based simulation as part of the holistic design and operational performance assessment of ship machinery systems. This need may rise in different stages of ship lifecycle, when model results are used and compared (e.g. as performance metrics for bids) therefore showing the need of model standardization. Four state-of-the-art Model-Based Systems Engineering (MBSE) tools are used for the assessment of the annual energy and emissions performance of an Offshore Supply Vessel, namely the DNV GL COSSMOS (COmplex Ship Systems MOdelling and Simulation), (2) the Rolls-Royce Marine MPSET (Marine Power System Evaluation Tool), (3) the TNO-SD GES (General Energy Systems) and (4) the BVSEECAT (Ship Energy Efficiency Calculation and Analysis Tool). The example marine energy system for the study comprises a hybrid-electric solution of two 4-stroke marine Diesel engines of 2880 break kW with power-take in/outcapability (1500/1200kW), two 4- stroke Diesel generators of 2765kW electrical production capacity and two energy storage devices of 500kWh. The consumers included two 4380kW mechanically driven contra-rotating propellers, two 1050kW tunnel aft thrusters, one 1150kW tunnel fore thruster and one 1200kW swing-up azimuth thruster. The level ofcomplexity of the integrated marine energy systems creates the need of advanced tools to identify the optimal dispatch of consumer loads to the engines and the batteries for higher energy efficiency and minimum emissions. The annual operation of the OSV’s powertrain was optimized using all four tools (MPSET and COSSMOS) for a known annualoperational profile, including hours in harbour, transit and dynamic positioning modes. The results between COSSMOS, GES, SEECAT and MPSET were compared and analysed revealing the critical stages to benchmark and the areas of necessary standardization. An absolute difference from the mean model result of 0 to 9% (4% in average)was observed for the total fuel consumption with minor differences between variant modes, highlighting the need of concrete case specifications and assumptions alignment when various MBSE systems are used. Differences in emissions calculations were found to be due to the different calculation model used. The emission differences were found to be larger than the fuel consumption differences, highlighting the need for respective standardisation to allow for objective evaluation in the design process. The stage of case specifications and modelling assumptions is the first critical step to ensure comparable results. Also, the definition of equivalent operating strategies of the hybridized system was shown to be important. This work is held as part the EC-funded project HOLISHIP (Horizon 2020), on the holistic, multiobjective, multi-disciplinary and multi-fidelity optimisation of ship design, operation and retrofitting.
Model-based systems engineering
To reference this document use:
Ship machinery modelling and simulation
Maritime & Offshore
2nd International Conference on Modelling and Optimisation of Ship Energy Systems, 8-10 May 2019, Glasgow, Scotland, UK