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Electric Ship Technologies Symposium, 2007. ESTS '07. IEEE

Date 21-23 May 2007

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  • Sizing Power Generation and Fuel Capacity of the All-Electric Warship

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    Current sizing algorithms for warship power generation and fuel tank capacity were developed over forty five years ago when ship service loads were a small fraction of the overall power demand. Electric load growth, particularly with the introduction of high power mission systems, results in ship service maximum margined loads being nearly the same as the maximum propulsion load. In many operating conditions, ship service power demands exceed propulsion demands. This paper proposes new sizing methods for all-electric warships that are tied to operational effectiveness. These sizing methods are based on mobility mission tactical situations such as high speed transit, economical speed transit, and on station time. Additionally, the methods are sensitive to drag reduction efforts, temperature, and the ability to maintain speed in higher sea states. The goal is to optimize shipboard power and propulsion system life cycle cost while meeting operational requirements. View full abstract»

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  • Integrated Electric Power and Propulsion System on Land An Overview

    Page(s): 7 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    This paper set out to describe the electric ship technology demonstrator and how it is being used to de-risk future technology. The main purpose of the project is to stretch the technology boundaries and extend the understanding. To this end the project is a success with the facility fully integrated and operating as an advanced system. View full abstract»

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  • Impact of Marine Power System Architectures on IFEP Vessel Availability and Survivability

    Page(s): 14 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    In recent years integrated full electric propulsion (IFEP) has become a popular power system concept within the marine community, both for the naval and the commercial community. In this paper the authors discuss the need for a detailed investigation into the impact of different IFEP power system architectures on the availability of power and hence on the survivability of the vessel. The power system architectures considered here could relate to either a commercial or a naval vessel and include radial, ring and hybrid AC/DC arrangements. Comparative fault studies of the architectures were carried out in an attempt to make valuable observations on the survivability of a vessel. Simulation results demonstrate that the ring and hybrid AC/DC architectural contribute to a higher survivability than the radial architecture. However, there are still challenges that need to be addressed and therefore potential solutions such as fault current limiters will be considered. View full abstract»

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  • Performance Metrics for Electric Warship Integrated Engineering Plant Battle Damage Response

    Page(s): 22 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    In military applications, it is important for a platform (warship, aircraft, etc.) or an installation (airbase, etc.) to maintain war fighting ability after being damaged. In particular, if the unit requires electric power, cooling, or other resources to perform its mission, then these resources must be available following a weapon detonation event. The integrated engineering plant is responsible for providing these services to the mission critical loads in a unit. Novel continuity of service metrics for integrated engineering plants are set forth. These metrics provide a quantitative means of predicting the worst case scenario for a given system, as well as the level of service the plant can provide under the worst case scenario. This provides a method of making meaningful comparisons between different designs. The computation and meaning of the proposed metrics are explored using the notional plant. View full abstract»

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  • U.S.S. Makin Island: Simulation-Based Analysis and its Role in Electric-Plant Control System Design

    Page(s): 30 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (761 KB) |  | HTML iconHTML  

    The LHD 8 amphibious assault ship (Makin Island) is currently under construction at Northrop Grumman Ship Systems, in Pascagoula, MS. A hybrid propulsion plant, in which the ship has the capability to be propelled by electric propulsion motors or gas turbine engines, exists aboard LHD 8. The electric propulsion motors provide for totally-electric propulsion for the majority of Makin Island's operation at low speeds. The Makin Island concept for electrical power generation, distribution, and electric propulsion represents the intent of the all-electric warship i.e., a highly automated electric-plant with minimal manning. This and other similar electric-plant system topologies offer alternate means of supplying power to loads by reconfiguring main distribution paths. Automated plant reconfiguration (load shedding) and power management is accomplished by a digital Machinery Control System (MCS) for various casualty or loading conditions. An Electric Plant Computer Model Simulation (EPCMS) is used to assess the impact of faults, plant stability, signal latencies, etc. with regards to the electric plant. Several system design configurations were analyzed during ship construction based on simulation results. This paper illustrates the role that dynamic simulation-based analyses can play in influencing electric plant designs as it applies to the parallel diesel generator load sharing algorithm and plant reconfiguration as well as an evaluation of the response of the existing simulated system and the relative improvement in response with the proposed upgrades. View full abstract»

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  • Large-Signal Stability Analysis in Power Systems with a Synchronous Generator Connected to a Large Motor Drive

    Page(s): 42 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (538 KB) |  | HTML iconHTML  

    This paper studies the large-signal stability of a synchronous generator connected to a motor drive of a similar power. The generator-motor drive set, with additional auxiliary lower power loads represents a simplified version of an all electric ship power system. The use of Lyapunov linearization method allows identifying the region of stable operation. This description is valid only locally. However, the boundaries of this region where the equilibrium points change their stability condition represent bifurcations of the nonlinear system. In addition, nonlinear behavior is likely to appear close to those boundaries. The paper also describes observed nonlinear behavior created by the action of hard limits in the system. View full abstract»

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  • Impedance Identification of Integrated Power System Components using Recurrent Neural Networks

    Page(s): 48 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    Impedance characteristics of shipboard power systems provide important information for studies on system stability and integration. Existing injection based impedance measurement techniques require multiple tests on the system to obtain characteristics over wide frequency ranges. In this paper, recurrent neural networks (RNNs) are used to model the small signal dynamics of power electronic systems based on a single test in which randomized signals are injected into the system. The trained RNN is then used to extract the small-signal impedances/admittances of the system. A number of tests have been carried out in simulation to verify the effectiveness of the proposed method. View full abstract»

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  • The Reduction of Simulation Software Execution Time for Models of Integrated Electric Propulsion Systems through Partitioning and Distribution

    Page(s): 53 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1019 KB) |  | HTML iconHTML  

    Software time-domain simulation models are useful to the naval engineering community both for the system design of future vessels and for the in-service support of existing vessels. For future platforms, the existence of a model of the vessel's electrical power system provides a means of assessing the performance of the system against defined requirements. This could be at the stage of requirements definition, bid assessment or any subsequent stage in the design process. For in-service support of existing platforms, the existence of a model of the vessel's electrical power system provides a means of assessing the possible cause and effect of operational defects reported by ship's staff, or of assessing the possible future implications of some change in the equipment line-up or operating conditions for the vessel. Detailed high fidelity time-domain simulation of systems, however, can be problematic due to extended execution time. This arises from the model's mathematically stiff nature: models of Integrated Electric Propulsion systems can also require significant computational resource. A conventional time-domain software simulation model is only able to utilize a single computer processor at any one time. The duration of time required to obtain results from a software model could be significantly reduced if more computer processors were utilized simultaneously. This paper details the development of a distributed simulation environment. This environment provides a mechanism for partitioning a time-domain software simulation model and running it on a cluster of computer processors. The number of processors utilized in the cluster ranges between four and sixteen nodes. The benefit of this approach is that reductions in simulation duration are achievable by an appropriate choice of model partitioning. From an engineering perspective, any net timing reduction translates to an increase in the availability of data, from which more efficient analysis and design follows. View full abstract»

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  • Modeling and Simulation of Electric Propulsion Systems for All-Electric Cruise Liners

    Page(s): 60 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (353 KB) |  | HTML iconHTML  

    Electric propulsion for cruise liners has now become a standard owing to its several advantages. However propulsion drives have a large impact on the ship power system. This gives rise to the requirement for designers to understand in depth the effects of propulsion drives on the ship network in different operating conditions. For this purpose computer simulations have proved to be a very useful tool. In the paper a typical propulsion drive for an all-electric cruise liner is described and simulation results are shown. Owing to the model complexity, simulations turn out to be computationally quite heavy. For this reason a simplified model has been developed. Simulation results, from the ship network viewpoint, proved to be close to the detailed model ones. View full abstract»

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  • Multi-Objective Design Optimisation of Submarine Electric Drive Systems

    Page(s): 65 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1019 KB) |  | HTML iconHTML  

    The design of an integrated electric propulsion (IEP) system is considered for naval submarine propulsion. A multi-objective genetic algorithm is used to explore potential IEP topologies and designs, including direct-drive, geared-drive and hybrid steam-turbine/electric drive. Typical submarine mission scenarios are simulated and trade-offs in performance are investigated. Compromises in propeller and electric motor efficiency are found, as are large discrepancies in electric motor technology and the technology required for the realisation of direct-electrical propulsion. Multiple electric motors and a hybrid drive approach are found to reduce this discrepancy to an extent that IEP becomes a feasible propulsion option. View full abstract»

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  • Suppression of the Thrust Loss for the Maximum Thrust Operation in the Electric Propulsion Ship

    Page(s): 72 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (681 KB) |  | HTML iconHTML  

    This paper presents a thrust loss suppression algorithm in an electric propulsion ship. From the viewpoint of the speed controller of the propulsion motor, the thrust loss due to cavitation can be regarded as a disturbance torque. The disturbance torque is estimated by means of a disturbance observer. Considering the estimated disturbance torque, the speed reference of the propeller is modified to suppress the thrust loss. The experimental results which performed in the cavitation tunnel with an electrically driven propulsion system are shown to verify the proposed algorithm. View full abstract»

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  • Modelling and Analysis of Electro-Mechanical Interactions between Prime-Mover and Load in a Marine IFEP System

    Page(s): 77 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1237 KB) |  | HTML iconHTML  

    This paper reports on the simulation of a marine Integrated Electric Full Electric Propulsion (IFEP) system to assess its ability to absorb variations in propulsion or auxiliary load without excessive degradation of the electrical supply quality or imposing excessive demands on the prime movers. IFEP systems are expected to yield economic benefits to ship operators by permitting the capacity of ship engines in use to be more closely tailored to the electrical demand of auxiliary and propulsion systems. However, the extent to which these savings can be realised at times of low demand is dependent on the ability of the shipboard electrical system to absorb disturbances. In this paper, simulations are conducted for a variety of frequencies of load variation, and the results assessed. Measures which might be taken to reduce the observed effects are suggested. View full abstract»

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  • Software in Maritime: Cost efficient Quality Management and Control

    Page(s): 85 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (262 KB) |  | HTML iconHTML  

    Software is to an increasing degree delivering value to the maritime industry through, e.g., optimized energy use, prolonged equipment life, bridge decision support, integrated control systems, alarm systems, and emergency shut-down systems. However, as the amount of software onboard vessels increases, so does the possibilities for undependable vessel behavior. Based on research performed in cooperation between yards, equipment manufacturers and standards professionals during a multinational, multi-organization joint industry project, it has become clear that there is a concern that the measures required by vessel and equipment buyers may not be fully adequate for tomorrow's software controlled vessels. Standard products are engineered into a system as one phase, and then integrated, parameterized, and tuned in a compressed time space, on site. Based on incidents investigated in the research project, needs for increased attention to certain foci areas in large scale software engineering are identified. Furthermore, a framework for overall quality assessment is suggested, based on suggestions from senior industry professionals in eight organizations from four European countries. View full abstract»

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  • Improved System Operational Availability (AO) through Autonomous Data Transfer and Analysis

    Page(s): 90 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB) |  | HTML iconHTML  

    A means to improved operational availability (Ao) of fielded Open Architecture (OA) Commercial Off The Shelf (COTS) systems is through enhanced transfer of system performance and logistics data and automating subsequent analysis and response processes. The Maintenance Free Operating Period (MFOP) initiative implemented as part of the sonar system deployed on US Navy submarines is leveraging the enhancement and automation. Off-hull data transfer from fielded MFOP sonar systems currently exists. Data is sent back to the system Life Cycle Integrator (LCI) as an e-mail attachment for manual analyses and response. Advancement in Remote Off-Hull Maintenance Support (ROHMS) and Autonomic Logistics (AL) analysis has transformed data transfer, analysis and response to be more automated vs. a manual procedural based approach. ROHMS is a WEB application with communication protocol links to MFOP system agents that retrieve data and transmit it back to the LCI. Data is then analyzed at the LCI by predetermined intelligent agents and logistics process triggers. Data transfer advancements paralleled by autonomic logistics analysis results in optimum support responses for improved System Ao. This concept of maintenance could also be applied to electric ship technologies. View full abstract»

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  • Dynamic Simulation Based Analysis of a New Load Shedding Scheme for a Notional Destroyer Class Shipboard Power System

    Page(s): 95 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (450 KB) |  | HTML iconHTML  

    In this article, an expert system based load shedding scheme for ship power systems is revisited. In this load shedding scheme, a popular decision making tool termed the analytical hierarchy process, is utilized for prioritizing the loads to be shed onboard a notional all-electric ship power system. The analytical hierarchy process based load shedding scheme overcomes some of the major drawbacks of traditional load shedding schemes implemented on ship power systems by minimizing the number of loads disconnected, differentiating the priority of loads based on system conditions, and considering a wider ranger of factors that may potentially influence the shedding of electrical loads. An illustration of the developed load shedding scheme implementation to a destroyer class shipboard power system simulated in a real time digital simulator is presented. View full abstract»

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  • Modeling and Testing of Protection Devices for SPS using MATLAB/Simulink and VTB

    Page(s): 103 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (394 KB) |  | HTML iconHTML  

    For both terrestrial and shipboard power systems (SPS), a protection system is essential to minimize the effects of faults in the system. SPS present challenges, such as increased fault vulnerability and lack of electrical ground in the system. For this reason, protection devices such as digital relays have to be designed such that the whole SPS protection system ensures the reliability and survivability of the electric ship. The development of elaborate digital protection devices requires appropriate tools for modeling, simulation, and testing. This paper explores the application of two software tools in protective relay modeling, simulation and testing. The first software tool is MATLAB/simulink and the second is the virtual test bed (VTB). An instantaneous overcurrent relay model has been developed using both software tools. To test this model, a transmission line protection application has been developed. In MATLAB/simulink, the proposed overcurrent relay model has been tested for fault conditions applied on a simple power system. The same test is replicated in VTB. Future work includes the implementation of the proposed overcurrent relay model on a hardware platform (dSPACE controller board) to perform hardware-in-the-loop (HIL) testing using a real-time simulation platform, such as the real-time extension of VTB, VTB-RT. View full abstract»

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  • Graph Trace Analysis Based Shipboard HM&E System Priority Management and Recovery Analysis

    Page(s): 109 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB) |  | HTML iconHTML  

    This paper presents a new priority management algorithm for use with interdependent, reconfigurable systems. It is based on a multidiscipline analysis approach called graph trace analysis (GTA) which was originally developed at Virginia Tech for integrated analysis and design of power utility systems. GTA's generic nature, combined with the collaborative environment it provides makes it possible to define and solve multidiscipline problems in new ways that closely follow the natural problem structure defined by the system. This simplifies integration, provides for fewer modification and extension problems in the future, and reduces analysis time. In addition to presenting the new algorithm together with a simple example problem, the paper also provides an overview of GTA and a description of shipboard system priority management from a multidiscipline GTA perspective. View full abstract»

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  • Meeting Harmonic Limits on Marine Vessels

    Page(s): 115 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (678 KB) |  | HTML iconHTML  

    Recent advances in power electronic drive converters have led to an increased use of this technology for electric propulsion and other variable speed drive applications on marine vessels such as ships and offshore oil platforms. The current and voltage harmonics these devices introduce however have caused marine regulating bodies to introduce strict harmonic voltage limits to ensure that the reliability of equipment and the safety of crews are not compromised by their use. In order to meet these new standards, methods to control harmonics must be adopted. This paper will discuss some of these methods and present an application where a unique wide spectrum passive harmonic filter was used to meet harmonic limits on a cable laying ship that previously required the use of rented generators to allow operation of variable speed drives. View full abstract»

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  • Insulated Bus Pipe (IBP) for Shipboard Applications

    Page(s): 122 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    The commercial shipbuilding industry and the U.S. Navy have decreed that the aim of the "all electric ship" power system design will be for survivability and continuity of electrical power supply. In general, ship service electric power and electric propulsion power requirements are approaching hundreds of megawatts. There are major challenges to the use of standard cable at medium voltage levels onboard due to cable stiffness, and cable bend radius requirements for distributing very high current around the ship. This paper examines the practical design and installation benefits associated with IBP as a possible alternative to shipboard electric power cable. Although IBP is widely used in the utility industry, the shipboard use of IBP is limited to several passenger cruise ships. IBP is considered a more efficient medium & high voltage transmission line over cable for integrated power system (IPS) ships due to cable size, quantity, and installation time. There are technical issues that must be resolved before advocating the use of IBP onboard Navy ships. This paper presents an overview of IBP technology, examines IBP technical issues and presents probable solutions for Navy and commercial shipboard applications. One of the probable solutions that are discussed is a new type of insulating material for IBP that should significantly enhance the Navy 3 hour gas flame circuit integrity flame test withstand capability. This paper recommends that the proven IBP prototypes and their models be the procurement specifications. The paper also recommends: (1) inclusion of IBP application recommended practices in shipbuilding standards such as IEEE-45 and IEEE-1580 (2) inclusion of IBP in ABS rules for commercial ships, ABS NVR for naval vessels, and other national and international shipbuilding rules and regulations. View full abstract»

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