On the Power Balancing of Diesel Engines in CODAD Ship Propulsion Plants

ABSTRACT: In a CODAD propulsion plant configuration, with two diesel engines assigned to a shaft line, the power balancing between the two diesel engines is managed by the propulsion plant governor mainly by equally distributing the fuel mass flow between the two engines, without verifying the effective power delivered by each engine. If one of the diesel engines of a CODAD propulsion plant runs under faulty conditions, its power is different, also in case of equal fuel mass flow, from that delivered by the other (un-faulty) diesel engine of the same propulsion system. Usually this power unbalancing cannot be detected by the engines governor and then cannot be corrected, with the consequence that one engine of the system (the un-faulty one) runs in overloading conditions. In this paper an improvement of the CODAD propulsion plant governor logic is proposed in order to cancel or reduce the power unbalance determined by an engine working in faulty conditions. The proposed improved governor scheme has been tested by simulating different engine failures through the use of a suitable CODAD propulsion system simulator, developed by the authors, and by comparing the simulation results with those obtained in case of a conventional governor.