Efficiency Estimation of Synchronous Generators for Marine Applications and Verification With Shop Trial Data and Real Ship Operation Data

Kifune, Hiroyasu; Zadhe, Mehdi Karbalaye; Sasaki, Hidetsugu

doi:10.1109/access.2020.3033404

Cited by 6 publications

(6 citation statements)

References 35 publications

(38 reference statements)

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“…The value of e reliq is dependent on the cryogenic fuel undergoing reliquefaction; due to its lower boiling point, LH2 requires more energy to reliquefy than LNG. Its value and the value of η gen can be determined from the literature (e.g., References [45][46][47][48]56,57]).…”

Section: Power Consumption and Fuel Utilisationmentioning

confidence: 99%

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Modelling of Boil-Off and Sloshing Relevant to Future Liquid Hydrogen Carriers

2022

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This study presents an approach for estimating fuel boil-off behaviour in cryogenic energy carrier ships, such as future liquid hydrogen (LH2) carriers. By relying on thermodynamic modelling and empirical formulas for ship motion and propulsion, the approach can be used to investigate boil-off as a function of tank properties, weather conditions, and operating velocities during a laden voyage. The model is first calibrated against data from a liquefied natural gas (LNG) carrier and is consequently used to investigate various design configurations of an LH2 ship. Results indicate that an LH2 ship with the same tank volume and glass wool insulation thickness as a conventional LNG carrier stores 40% of the fuel energy and is characterised by a boil-off rate nine times higher and twice as sensitive to sloshing. Adding a reliquefaction unit can reduce the LH2 fuel depletion rate by at least 38.7% but can increase its variability regarding velocity and weather conditions. In calm weather, LH2 boil-off rates can only meet LNG carrier standards by utilising at least 6.6 times the insulation thickness. By adopting fuel cell propulsion in an LH2 ship, a 1.1% increase in fuel delivery is expected. An LH2 ship with fuel cells and reliquefaction is required to be at least 1.7 times larger than an existing LNG carrier to deliver the same energy. Further comparison of alternative scenarios indicates that LH2 carriers necessitate significant redesigns if LNG carrier standards are desired. The present approach can assist future feasibility studies featuring other vessels and propulsion technologies, and can be seen as an extendable framework that can predict boil-off in real-time.

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Section: Power Consumption and Fuel Utilisationmentioning

confidence: 99%

“…Thus, no fuel is reliquefied, and the total fuel depleted is equal to that utilised for propulsion. Efficiency of Generator (Independent of Engine, Approximately Mid-Range) % 92.5 [56] * At a pressure of 1.01325 bar and the vapour temperature detailed in Table 5.…”

Section: Addition Of a Reliquefaction Unitmentioning

confidence: 99%

Modelling of Boil-Off and Sloshing Relevant to Future Liquid Hydrogen Carriers

2022

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“…Therefore, identical power losses occur in generators and motors. The copper, iron, and mechanical losses are the significant losses in these machines [6], [16], [17]. As the copper loss (P Loss,Cu ) is the sum of power losses in the stator and rotor windings, it is load-dependent and can be expressed as…”

Section: System Overviewmentioning

confidence: 99%

Dynamic Efficiency Modeling of a Marine DC Hybrid Power System

Ghimire

Zadeh

Pedersen

et al. 2021

2021 IEEE Applied Power Electronics Conference and Exposition (APEC)

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With the share of high-power electronic converters, the emerging marine DC hybrid power systems have been increasingly attractive for ship designers because of their higher operational flexibility. The system efficiency analysis, one of the critical factors while embracing an emerging system, requires a detailed estimation and evaluation. Conventionally, the rated efficiency for each component is the basis for the system efficiency estimation. However, the efficiency may vary with the loading conditions in any component, directly affected by the actual load and the load-sharing strategies. In this work, dynamic efficiency models are developed for the DC hybrid power system components, which are used to estimate the overall system efficiency using a realistic load power profile and a rule-based power and energy management system (PEMS). The efficiency analysis shows that the overall power efficiency increases with optimal battery usage in a hybrid power system. Moreover, three different power-sharing control strategies are compared. The modified rule-based PEMS offers the highest efficiency, while conventional diesel generator operation offers the least efficiency for the given load profile and power system configuration.

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“…The modeling of losses in the electric machines through polynomial curve fitting using the data available in commercial data sheets are presented in [24]. The synchronous generator's efficiency estimation methods are established and verified with the shop trial and real ship operational data in [25]. The high power drives efficiency calculations are discussed in [26].…”

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confidence: 99%

Data-Driven Efficiency Modeling and Analysis of All-Electric Ship Powertrain: A Comparison of Power System Architectures

Ghimire

Zadeh

Thorstensen³

et al. 2022

IEEE Trans. Transp. Electrific.

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In this paper, a data-driven dynamic efficiency model is developed for efficiency evaluation and comparison of ship electric powertrain with various system configurations and load-sharing methods. Based on the proposed method, the entire powertrain efficiency is assessed from the fuel consumption to the propulsion unit and the rest of the onboard load. The efficiency model is repeated for the conventional diesel-electric and the hybrid power system with batteries. In the latter case, the efficiency of the battery system is also included in the model. Then, the analysis is extended for different power system architectures such as AC-and DC onboard power systems. As a case study, system efficiency in a cruise ship is investigated using a real operational profile. A comprehensive analysis is performed to demonstrate the loss distribution in each subsystem of a hybrid AC-and DC power system. For a fair comparison between AC and DC, the battery charge level is equalized based on fuel compensation. The case study shows that hybridizing the ship power system increases system efficiency and enhances operational flexibility for the studied use case vessel. Further, the DC hybrid power system can improve the efficiency of the whole ship powertrain thanks to the variable speed operation of engines.Index Terms-Electric propulsion, ship hybrid power systems, power system efficiency, AC & DC power system. I. INTRODUCTIONW ITH the ever-increasing onboard electrical power demand, the ship power systems evolve gradually to a complex system [1]. The complexity is even increased due to incorporating energy storage devices (ESDs), highly dynamic consumers, and various energy carriers, which do not operate in the same power system. Thus, the discussion of alternating current (AC) vs. direct current (DC) is once Manuscript

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Efficiency Estimation of Synchronous Generators for Marine Applications and Verification With Shop Trial Data and Real Ship Operation Data

Cited by 6 publications

References 35 publications

Modelling of Boil-Off and Sloshing Relevant to Future Liquid Hydrogen Carriers

Modelling of Boil-Off and Sloshing Relevant to Future Liquid Hydrogen Carriers

Dynamic Efficiency Modeling of a Marine DC Hybrid Power System

Data-Driven Efficiency Modeling and Analysis of All-Electric Ship Powertrain: A Comparison of Power System Architectures

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