A Combinatorial Safety Analysis of Cruise Ship Diesel–Electric Propulsion Plant Blackout

Abstract

Diesel–Electric Propulsion (DEP) has been widely used for the propulsion of various ship types including cruise ships. Considering the potential consequences of blackouts, especially on cruise ships, it is essential to design and operate the ships’ power plants for avoiding and preventing such events. This study aims at implementing a comprehensive safety analysis for a cruise ship Diesel–Electric Propulsion (DEP) plant focusing on blackout events. The Combinatorial Approach to Safety Analysis (CASA) method is used to develop Fault Trees considering the blackout as the top event, and subsequently estimate the blackout frequency as well as implement importance analysis. The derived results demonstrate that the overall blackout frequency is close to corresponding values reported in the pertinent literature as well as estimations based on available accident investigations. This study deduces that the blackout frequency depends on the number of operating Diesel Generator (DG) sets, the DG set’s loading profile, the amount of electrical load that can be tripped during overload conditions and the plant operation phase. In addition, failures of the engine auxiliary systems and the fast-electrical load reduction functions, as well as the power generation control components, are identified as important. This study demonstrates the applicability of the CASA method to complex marine systems and reveals the parameters influencing the investigated system blackout frequency, thus providing better insights for these systems’ safety analysis and enhancement.

Dynamic Blackout Probability Monitoring System for Cruise Ship Power Plants

“…Other methods/software tools could be also used, such as Hip-HOPs [24], COMPASS [25] or MADe [26][27][28] for automatically deriving the Fault Tree or Dynamic Fault Trees. This study employs the Combinatorial Approach to Safety Analysis (CASA) method, which is presented in [29][30][31]. The CASA method advantage is that it captures more accurately the dynamic and software-intensive character of cyber-physical systems compared to the classical Fault Tree Analysis [29].…”

“…Methods such as Boolean-Driven Markovian Processes, Hip-HOPs, COMPASS, or MADe do not capture properly the software-intensive character of cyberphysical systems. Therefore, the use of fault trees developed by employing the CASA method is considered as advantageous for the safety analysis in diesel-electric power plants (DEP) system as reported in [30].…”

“…The use of these equations constitutes an improvement to the CASA calculations, as they allow for estimating the selected safety metrics time variations, compared to the static predictions of the previously presented approaches [29,30].…”

“…Prewarning alarms can allow a DG set to switch over to a healthy DG set, for example, in cases of lubricating oil low-pressure alarm, high exhaust gas temperature alarm and high cooling water temperature alarm are present. More detailed information about the investigated system can be found in [30].…”

“…The analysis and simulations require reliability and maintenance interval data for the components of the investigated power plant. However, this data sets were already presented in [30], and for reasons of brevity, are not provided herein.…”