Browsing by Subject "Electric ship"
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Item Directly-Coupled Gas Turbine Permanent Magnet Generator Sets for Prime Power Generation on Board Electric Ships(IEEE, 2007-05) Vijlee, S.; Ouroua, A.; Domaschk, L.N.; Beno, J.H.Prime power generation on board all-electric ships presents several options that affect fuel consumption, power density, operational effectiveness, and survivability. A study that aims at understanding the effects of some of these options has been conducted and results are reported in this paper. It is found that direct coupling of gas turbines to permanent magnet generators reduces system mass and volume significantly as compared to electric power generation systems installed on present-day navy ships. Furthermore, it is found that a significant benefit this topology brings is a reduction in gas turbine air duct volume if the compact gen-set units are relocated on or near the ship's upper decks. In addition, a combinatory analysis revealed that the choice of the number of generating units and their respective power levels has a significant influence on overall efficiency.Item Distribution network topology design for renewable energy integration and high resiliency(2018-09-25) Jothibasu, Suma; Santoso, Surya; Baldick, Ross; Arapostathis, Aristotle; King, Carey; Feng, XianyongPresent-day electric power distribution grid faces multiple challenges in maintaining high power quality standards. This dissertation aims to examine and design modern distribution grid topologies that can provide reliable power service to customers at all times. One of the recent challenges in distribution grids is imposed by increased residential PV integration. A detailed analysis on its impacts on different grids is conducted and a generalization on factors that affect high PV integration in distribution grid is provided. Based on the study, an optimization framework is proposed to design distribution grid topologies with high PV hosting capacity, while maintaining the required power quality standards. Furthermore, new topologies are designed for networks with high resiliency needs. In this work, a specific application of electric ship networks that are commissioned for military use is studied in detail, but the design approach is applicable for other networks as well. Finally, a reduced-scale hardware test-bed design for distribution grid analysis with distributed energy resources like PV, storage and capacitors is described in this dissertation. As a part of the hardware development, a novel programmable load model that can provide variable fundamental and harmonic load characteristics is proposedItem Electric power system concepts for integration of advanced sensor and pulsed loads in the DDG-51 class ships(0000-00-00) Herbst, J.D.; Pish, S.P.; Jackson, J.R.; Gully, B.; Gattozzi, A.L.Advanced weapons and sensors increase demand on the electric power systems of Navy surface combatants, driving the need for fully Integrated Power Systems (IPS) such as those found in the DDG-1000 Zumwalt class of ships. The goal of this paper is to introduce novel power system configurations that could potentially be integrated into future flights of the DDG-51 class to support expanded electric power system capability at reasonable cost. Two concepts are presented: the first addresses the need for additional power for advanced sensor systems and the second addresses the need for a more significant increase in capacity to support higher power electric loads.Item Fault location and characterization in AC and DC power systems(2012-12) Kulkarni, Saurabh Shirish; Santoso, SuryaThe focus of this research is on identification, location, interruption, characterization and overall management of faults in conventional AC distribution systems as well as isolated MVDC power systems. The primary focus in AC distributions systems is on identifying and locating underground cable faults using voltage and current waveforms as the input data. Cable failure process is gradual and is characterized by a series of single-phase sub-cycle incipient faults with high arc voltage. They often go undetected and eventually result in a permanent fault in the same phase. In order to locate such incipient cable faults, a robust yet practical algorithm is developed taking into account the fault arc voltage. The algorithm is implemented in the time-domain and utilizes power quality monitor data to estimate the distance to the fault in terms of the line impedance. It can be applied to locate both sub-cycle as well as permanent faults. The proposed algorithm is evaluated and proved out using field data collected from utility distribution circuits. Furthermore, this algorithm is extended to locate evolving faults on overhead distribution lines. Evolving faults are faults beginning in one phase of a distribution circuit and spreading to another phase after a few cycles. The algorithm is divided into two parts, namely, the single line-to-ground portion of the fault and the line-to-line-to-ground portion of the fault. For the single line-to-ground portion of the fault, the distance to the fault is estimated in terms of the loop or self-reactance between the monitor and the fault. On the other hand, for the line-to-line-to-ground and line-to-line portion of the fault the distance is estimated in terms of the positive-sequence reactance. The secondary focus of fault management in AC distribution systems is on identifying fault cause employing voltage and current waveform data as well as meteorological information. As the first step, unique characteristics of cable faults are examined along with methods to identify such faults with suitable accuracy. These characteristics are also used to distinguish underground cable faults from other overhead distribution line faults. The overhead line faults include tree contact, animal contact and lightning induced faults. Waveform signature analysis, wavelet transforms and arc voltages during the fault event are used for fault cause identification and classification. A statistical based classification methodology to identify fault cause is developed by utilizing promising characteristics. Unlike the AC system infrastructure which is already in place, the DC system considered in this document is that of a notional electric ship. The nature of DC current, with the absence of a current zero as well as the presence of power electronic devices influencing the current behavior, makes interrupting DC fault currents challenging. As a part of this research an innovative DC fault interruption scheme is proposed for rectifier- fed MVDC systems. A fault at the terminals of a phase-controlled rectifier results in a high magnitude current impulse caused by the filter capacitor discharging into the fault resistance. It is proposed to use a series inductor to limit the magnitude of this current impulse. The addition of the inductor results in an underdamped series RLC circuit at the output terminals of the rectifier which causes the fault current to oscillate about zero. Furthermore, it is proposed to utilize a conventional AC circuit breaker to interrupt this fault current by exploiting the zero crossings resulting from the oscillations. Using the proposed scheme for the example case, the peak fault current magnitude as well as the interruption time is significantly reduced.Item Modeling and Simulation Roadmap to Enhance Electrical Energy security of U.S. Naval Bases(Office of Naval Research, 2012-04) Hebner, R.E.; Herbst, J.D.; Gattozzi, A.L.; Uriarte, F.M.The enhancement of the electrical energy security of Navy bases within the continental U.S. has been studied using an approach based on modeling and simulation, with the intent to achieve real time control and energy management. The commercially available software packages are reviewed and the most suitable ones are indicated. A notional base was developed and used for this study. Its format is general enough to be able to be used as a template for each specific Navy installation. Several preliminary simulations using commercial software have been performed on the power system of this notional base addressing a variety of operating scenarios including islanded mode and the impact of wind and solar power sources. Results of steady state and transient operation are also reviewed. The results of these simulations indicate that existing software packages available today, with proper adaptations, can provide a well validated and consistent process for evaluating power system architectures and technologies and, therefore, can become a valuable tool for the implementation of the described plan for Navy bases. The study concludes giving the details of the roadmap to move forward in the process of energy security enhancement of U.S. Navy bases through modeling and simulation.Item Power System and Energy Storage Models for Laser Integration on Naval Platforms(2015-06) Gattozzi, A. L.; Herbst, J. D; Hebner, R. E; Blau, J. A; Cohn, K. R; Colson, W. B; Sylvester, J. E; Woehrman, M. A.High power solid state laser systems are being developed for advanced weapons and sensors for a variety of Department of Defense applications including naval surface combatants. The transient power and cooling requirements of these emerging technologies present significant challenges to the electric power distribution and thermal management systems, particularly for applications requiring back fit of the new systems onto existing platforms with limited electric power generation and cooling capacities.