By Topic

Electric Ship Technologies Symposium, 2005 IEEE

Date 25-27 July 2005

Filter Results

Displaying Results 1 - 25 of 84
  • Two techniques for modeling an induction motor with skewed slots with a time-stepping 2D-3D finite element method

    Page(s): 463 - 467
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    This paper presents the computation of the effect of rotor skewing in induction machines. Two cases of rotors with an identical number of bars but different skewing angles (0 and 10.23 degrees) are compared. This analysis is based on results obtained from measurements on a skewed rotor bars induction machine; results computed using a 2D (non skewed model) simulations; and results computed using a skewed model simulation. A new application called SKEW, neither to 2D nor 3D, has been developed and implemented in a commercial FEM software. Two approaches were considered in developing the application SKEW: the N-slice model and the extruded model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electric ship power system integration analyses through modeling and simulation

    Page(s): 70 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    The Center for Electromechanics (CEM) at the University of Texas is engaged in the development of a comprehensive power system model in order to address several challenging issues facing the development of a viable and effective integrated power system architecture for future naval platforms. The power system under consideration reflects the notional DD power system architecture and is developed in the Matlab/Simulink environment. System components such as motors and generators are modeled using parameters based on actual machine design and analysis work performed at CEM. Simulation results of models including permanent-magnet propulsion motors and generators with simple reconfiguration scenarios simulating loss and recovery of power to propulsion and vital loads are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reconfiguration: a tool for designing new ships

    Page(s): 81 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    The objective of reconfiguration is to re-route power during failure or compromised conditions to improve fight through capability and survivability. Rapid algorithms for the task may serve the dual purpose of managing power flow under dynamic load change. Among the critical constraints of power redirection is the line current rating. Reconfiguration algorithms serve an equally useful task in system grid design. An exhaustive search optimization routine can be used to specify grid layout necessary to guarantee 100% performance in the face of single and multiple line loss. A genetic optimization routine is employed to determine required line rating and switch configuration during generator loss to satisfy critical load demands. The combination of these tests results in line current rating and switch locations necessary for reliable ship operation for the least cost. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • System reconfiguration on shipboard DC zonal electrical system

    Page(s): 86 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    In this paper, an automated agent based reconfiguration scheme has been proposed for the DC zonal shipboard electrical system (SES). It is shown that the scheme can reconfigure the system following a disturbance in order to maintain the continuity of supply to loads. The paper identifies the main design issues, which include the number and location of the sectionalizers, primary and secondary DC bus configurations. The paper illustrates that with proper design, the automated reconfiguration can provide the expected performance with regards to continuity and quality of supply to loads. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal shipboard power system management via mixed integer dynamic programming

    Page(s): 55 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (413 KB) |  | HTML iconHTML  

    Power systems involve continuous and discrete components and controls. The modeling of 'hybrid' power systems using a logical specification to define the transition dynamics of the discrete subsystem is described. A computational tool for reduction of the logical specification to a set of inequalities is discussed. The use of the transformed model in a dynamic programming approach to the design of optimal feedback controls is described. Examples are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Materials for advanced electric machines: an overview

    Page(s): 478 - 480
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (165 KB) |  | HTML iconHTML  

    Materials behavior, along with the machine design, controls the performance of the electric machine. Advanced electric machines are placing increased demands on materials behavior especially to achieve power density, efficiency, and endurance. For the electric ship, such advanced electric machines include actuators, motors, generators, certain energy storage systems, electric clutches and brakes, and specialized machines for weaponry. Small engineering refinements from practice are often inadequate for the advanced electric machine systems and the associated materials utilized in these machines to meet performance goals. A method for directing appropriate attention to materials requirements based on the machine performance goals is needed. This paper presents a method for prioritizing materials issues based on ten machine performance categories. As each advanced electric machine presents a unique set of requirements, the prioritization guides valuing of associated materials issues. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Investigating singularities of the observability Jacobian for nonlinear power systems

    Page(s): 75 - 80
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (287 KB) |  | HTML iconHTML  

    This paper focuses on computing and interpreting the significance of the observability Jacobian singularities. Previous efforts have focused on developing an observability index and determining the effects of model/measurement changes to the observability formulation. Using this index, the singularities of the Jacobian are extracted, and preliminary results indicate that there is a duality between the loss of stability (whether it be phase or voltage stability), and the loss of observability. Thus, providing a single dual-use metric capable of forecasting both stability and observability characteristics of a system. The results are illustrated using a sample 3-bus system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Grounding and ground fault protection of bussed stand-alone generators

    Page(s): 112 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB) |  | HTML iconHTML  

    High impedance grounding of direct connected generators is considered in this paper, along with the detection of ground faults within the generator zone of protection. This paper discusses several possible grounding schemes, and compares the damage measure for these devices. Finally, the paper considers a method of detecting the location of ground faults that do occur on the system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced high-speed flywheel energy storage systems for pulsed power applications

    Page(s): 379 - 386
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (379 KB) |  | HTML iconHTML  

    A flywheel energy storage system (FESS) for naval applications based around a high-speed surface mount permanent magnet synchronous machine (PMSM) is explored in this paper. A back-to-back converter controls the bi-directional flow of energy for charging and discharging the flywheel. At first, the impacts of power factor and armature reaction on the operation of the PMSM are discussed and then the developed control method is outlined. Finally, the operation of the FESS in the discharge mode with leading power factor and no armature reaction is explained. The overall system is simulated in PSIM package and the results are presented as a proof of what has been claimed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Real and reactive power analysis for interharmonics

    Page(s): 244 - 247
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    Due to the non-harmonic nature of interharmonics, power flow analysis associated with interharmonic frequencies has not been intensively studied. Hence, we propose the use of the cross power spectrum technique for interharmonic power analysis. The cross power spectrum allows one to determine the magnitude and direction of real and reactive power flow at every frequency of interest. Therefore, the method appears to be an appropriate tool for interharmonic power analysis. The efficacy of the proposed method is demonstrated through an investigation of voltage and current waveforms from a simulated current source type inverter drive system based on ATP-EMTP. It is shown that power flow associated with interharmonic events can be better understood in a quantitative manner with the use of the cross power spectrum method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Testing a 5 MW high-temperature superconducting propulsion motor

    Page(s): 206 - 213
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB) |  | HTML iconHTML  

    A prototype marine propulsion motor manufactured by American Superconductor Corporation has been tested in the advanced test facility at the Center for Advanced Power Systems at Florida State University. The rotor of this 5 MW synchronous machine is constructed of high-temperature superconducting wire; the three-phase stator is of conventional wire. Testing was conducted with a dynamometer consisting of two 2.5 MW induction motors which permitted a wide range of conventional and novel procedures to be carried out for the characterization of the HTS motor. These tests and some of their results are discussed. The HTS motor functioned satisfactorily in all tests. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Operational experience with intelligent software agents for shipboard diesel and gas turbine engine health monitoring

    Page(s): 184 - 194
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (559 KB) |  | HTML iconHTML  

    The power distribution network aboard future navy warships are vital to reliable operations and survivability. Power distribution involves delivering electric power from multiple generation sources to a dynamic set of load devices. Advanced power electronics, intelligent controllers, and a communications infrastructure form a shipboard power distribution network, much like the domestic electric utility power grid. Multiple electric generation and storage devices distributed throughout the ship will eliminate dependence on any single power source through dynamic load management and power grid connectivity. Although new technologies are under development, gas turbine and diesel generators remain as the likely near-term power sources for the future all-electric ship integrated power system (IPS). Health monitoring of these critical IPS power sources are essential to achieving reliability and survivability goals. System complexity, timing constraints, and manning constraints will shift both control and equipment health monitoring functions from human operators to intelligent machines. Drastic manning reductions coupled with a large increase in the number of sensor monitoring points makes automated condition-based maintenance (CBM) a stringent requirement. CBM has traditionally been labor intensive and expensive to implement, relying on human experiential knowledge, interactive data processing, information management, and cognitive processing. The diagnostic robustness and accuracy of these embedded software agents are essential, as false or missed diagnostic calls have severe ramifications within the intelligent, automated control environment. This paper presents some of the first reported results of intelligent diagnostic software agents operating in real-time onboard naval ships with gas turbine and diesel machinery plants. The agents are shown to perform a substantial amount of CBM-related data processing and analysis that would not otherwise be performed by the crew, including real-time, neural network diagnostic inferencing. The agents are designed to diagnose existing system faults and to predict machinery problems at their earliest stage of development. The results reported herein should be of particular interest to those involved with future all-electric - ship designs that includes both gas turbine and diesel engines as primary electrical power sources. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of the energy flow characteristics in power electronic conversion systems

    Page(s): 333 - 339
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    The way to cost reduction and improved reliability in power electronic converters passes through their modularization and standardization. After the system is partitioned into modules, the characteristics of the interfaces acquire major importance because they provide the information necessary for module interconnection. This paper contributes to the description of the energetic characteristics of the interfaces in a modular system. In order to achieve the goal the energy flow in a power electronic converter is analyzed using proper analytic tools. The analysis is also useful to gain insight on how a power converter processes the energy and eventually find ways for modularization and an improved design. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The load as an energy asset in a distributed architecture

    Page(s): 261 - 267
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB) |  | HTML iconHTML  

    As future naval ships become more electrically integrated, the ability to manage the total energy resources becomes critical. Currently these functions are available only through a centralized controller, which limits flexibility, reconfigurability, and reliability. These limitations can be avoided, and still provide system level coordination through distributed controls based on local information. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced commercial power system protection practices applied to naval medium voltage power systems

    Page(s): 444 - 450
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    In the U.S. navy's transition to an all-electric ship, system designers must take great care to ensure that critical design choices provide highly reliable and safe power system operation and protection during all mission scenarios. Transitioning from low voltage (450 VAC) radial configurations to medium voltage (13.8 kVAC) multi-source systems requires new naval protection schemes. This paper specifically analyzes methods for quickly determining ground faults in ungrounded and high-impedance grounded naval power systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Five-phase permanent magnet motor drives for ship propulsion applications

    Page(s): 371 - 378
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    Multi-phase machines are very good candidates for ship propulsion application. In this paper, first a literature survey on the work accomplished in the area of multi-phase, split-phase and dual stator machines are presented. In the rest of the paper, additional degrees of freedom in multi-phase permanent magnet machines are employed to improve the overall performance of the system. Among all, the paper suggests and focuses on four significant features of multi-phase machines. First, the ability of injecting harmonic of currents in the motor and improving the torque production capability is discussed. Second, better torque and flux adjustment in DTC controlled multi phase motor is presented. Third, fault resilient current control of multi phase drive under loss of phases is examined. Finally the possibility of controlling multi motors through a single inverter is pointed out. The five phase permanent magnet motor is considered in this paper as an example. However the concept can be extended to higher number of phases. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the cause of arcing faults in low voltage switchboards

    Page(s): 125 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (746 KB) |  | HTML iconHTML  

    It is widely recognized that arcing faults in switchboards contain large amounts of power and can create significant damage including melting switchboards, destroying substations, disabling ships, and causing human fatalities. While arcing faults occur with a fairly high frequency, electricity is so ubiquitous in our lives that most engineers are not personally associated with a major arcing fault. The navy has invested twenty five years investigating the causes, behavior, and prevention of arcing failures in low and medium voltage switchboards. Laboratory testing used to help understand the behavior of arcs in switchboards is presented. That data is then used to analyze actual switchboard arcing events and thus to determine the root causes of the events. Additional testing used to confirm the cause of each event is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study on health assessment of generator winding insulation

    Page(s): 468 - 477
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB) |  | HTML iconHTML  

    Reliable operation of a generator is critically dependent on the integrity of its stator winding insulation. As this insulation is exposed to a wide variety of stresses like thermal, electrical and mechanical, it deteriorates on use over the time leading to failure. These stresses may be continuous, cyclic or intermittent. In addition, factors such as the presence of moisture, corrosive materials and radiation can lead directly to insulation breakdown, or to accelerate the aging process from voltage, temperature and mechanical vibration. Unexpected failure in the insulation may cause serious expenses for material, repair work and unplanned non-availability. To steer clear of unplanned outages periodic diagnostic tests on the insulation have become an integral part of the condition monitoring for generators. Such diagnostic tests generally include non-destructive measurements of various parameters associated with the winding insulation. In the paper efforts have been directed towards the residual life assessment of winding insulation of the existing units in India. This would help in not only the determination of the potential of the existing plants, but would also facilitate in planning for the capacity addition. Some researchers have adopted these methods for life prediction of the samples of the used winding insulations assuming different endurance models and others have tested to the breakdown voltage of winding, which is believed to be related to the residual life of insulation. This paper reviews the various life models under individual stresses and their combinations along with the statistical methods for estimation of residual life of stator winding insulation. The paper also critically discusses the various non-destructive tests and diagnostic parameters, which are helpful in assessing the health of the insulation and HV breakdown and withstand tests to correlate them to its residual life. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A reconfigurable induction motor drive with harmonic cancellation feature

    Page(s): 93 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    This paper proposes a reconfigurable induction motor (IM) drive with harmonic cancellation ability for shipboard power grids. Power electronic building blocks (PEBBs) and universal controllers (UCs) are used for reconfigurable (multi-function) control. When there are no significant current harmonics in the power grids, the UC controls the IM only. When significant current harmonics are introduced in the power grid, the UC reconfigures the active front end from an active rectifier to an active filter to cancel the harmonics while continuing to control the IM. Therefore, this reconfigurable drive system is universal in applications for harmonic cancellation requirement as well as controlling the existing IM. It supports power quality considerations without adding more equipment to the power system and therefore reduces the shipboard power system cost. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ship electrical system simulation

    Page(s): 63 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (295 KB) |  | HTML iconHTML  

    Several ship systems were evaluated as part of the "HTS benefits to ship system" study funded by the U.S. Office of Naval Research (ONR) in 2004. A commercially available power system simulation software application called PSCAD was used to evaluate the dynamic response of the selected ship electrical systems. The generic, large combatant ship electric systems reported here consist of the following: 1) two 36.5 MW propulsion motors with their variable speed drives (VSDs), 2) two 36 MW generators with gas turbines, and 3) Two 4 MW auxiliary generators for auxiliary loads. Each system studied employed rotating machines that were built using high-temperature superconductor (HTS) wires. The PSCAD software enabled modeling of electrical systems with full transient details to study the dynamic response of the electric system over a wide frequency range. The default models and standard features available in PSCAD served all the requirements. A number of fault and load scenarios were studied. The goal of this simulation work was to develop a model for studying the dynamic behavior of the ship electrical system. This goal was successfully achieved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modem, high-converter-populations argue for changing how to design naval electric power systems

    Page(s): 280 - 283
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    U.S. Navy ships, being designed presently, employs an increasing number of power electronic power converters, particularly in ships with integrated power systems wherein all loads, including propulsion, are supplied through converters. Looking into future missions and capabilities and technologies leads to the conclusion that this trend is not very likely to change. A discussion of the historical approach to the design of U.S. Navy naval electric power systems offers insights into the effect of capabilities and technology on how such systems are designed. These insights indicate the need for a new, different approach to design, one that is mission-operations oriented and load-centric. Acknowledging some characteristics of power electronic power converters implies additional changes to how naval electric power systems are designed. Perhaps it is time to develop, then explicitly articulate a new design approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Active compensator prototyping tools for electric ship applications

    Page(s): 268 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    Future naval electric distribution systems will require compensation of harmonic distortion caused by numerous power electronic converters. Active compensation with various control methods and active compensator configurations have been proposed as a solution. In order to efficiently evaluate the various options, prototyping tools and procedures are developed. Namely, a hardware-in-the-loop prototyping tool is developed using commercially available hardware and software from National Instruments. It allows the developer to evaluate performance of a DSP based digital controller without the need to complete the entire hardware prototype of the active compensator. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Constant power loads and negative impedance instability in sea and undersea vehicles: statement of the problem and comprehensive large-signal solution

    Page(s): 313 - 320
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (442 KB) |  | HTML iconHTML  

    Power electronic converters are usually loaded by passive loads or combinations of passive elements and voltage and current sources. However, there is an emerging vehicular system configuration where converters are loaded by power converters and a better model for the load is a constant power model. This converter operation appears in multi-converter applications such as advanced sea and undersea vehicles where a main converter has as loads a set of converters operating in closed-loop with tight output voltage regulation. This set of converters present at the input terminals a dynamic behavior similar to a constant power load (CPL) for a range of input voltages and a frequency span that ranges from DC up to the bandwidth of the converters. The primary goal of this paper is the development and extension of a technique for large-signal analysis of power electronic converters operating with constant power loads in sea and undersea vehicles using a phase plane analysis. This proposed approach could be used to present advantages and limitations of different controllers and, based on that analysis, define the selection and synthesis of controllers to achieve the required performance and robustness of the system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Augmenting E-ship power system evaluation and converter controller design by means of real-time hardware-in-loop simulation

    Page(s): 171 - 175
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    This paper evaluates the performance of an industrial power electronic building block (PEBB) controller in a large scale all electric ship power system by means of real-time hardware in the loop (RT-HIL) simulation. As an example relevant to future all electric navy ships, transients originating from the charging circuit of a pulse power load integrated with the prolusion motor drive and its impact on the system are studied. Different solutions to mitigate the impact by coordinating the power sharing between the pulse load's energy storage system and the ship propulsion motor drive are proposed and evaluated. The second part of the paper discusses how the RT-HTL tool can be used for system-wide performance optimization. Experimental results show the effectiveness of this method in finding the optimal parameter setting for the voltage loop control. It is concluded that due to distinct advantages of the RT-HTL method over conventional (off-line) simulations for system response analysis as well as for performance optimization, RT-HTL shall be employed more rigorously for electric ship system designs in the future. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effectiveness of generator control strategies on meeting pulsed load requirements in ship electric systems

    Page(s): 459 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    The performance of a notional fully-integrated ship power system with a pulsed power combat system load was analyzed in the virtual test bed (VTB). Two traditional voltage control strategies (General Electric SCR excitation control and Westinghouse brushless control) and a nonlinear voltage control based on the Lyapunov direct method were implemented as voltage control for the synchronous generator. The power system is simulated for each of the three control strategies and responses to the pulsed power load are compared. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.