Browsing by Subject "ESRDC"

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Accelerating the Simulation of Shipboard Power Systems
(Society for Modeling & Simulation International, 2011) Uriarte, F.M.; Hebner, R.E.; Gattozzi, A.L.
This paper presents an approach to accelerate the simulation of shipboard power systems. A common issue in the ship research community is the simulation run time of large-scale shipboard power systems. A contributor to lengthy run times is that PC-based power system simulators do not exploit multicore technology, which stems from the fact that software trails advances in hardware. The Center for Electromechanics at the University of Texas at Austin (UT-CEM) is developing a multicore power system solver (CEMSolver) to simulate shipboard power system models in significantly less time. The simulation run time is reduced by first partitioning power system models and then creating simulations at the subsystem level. This accelerates the simulation of shipboard power systems. A general overview of CEMSolver and a comparison of its run times against those of SimPowerSystems are presented. The results demonstrate thatCEMSolver can speed up the simulation of shipboard power system models built with SimPowerSystems up to 80 times, and that, despite common belief, multicore desktop computers are capable of executing complex simulation scenarios.
Analysis of Fault Events in MVDC Architecture
(IEEE, 2009-04) Ouroua, A.; Beno, J.H; Hebner, R.E.
Effective interruption of load currents under both normal and fault conditions presents major challenges in medium-voltage DC distribution systems. In a highly-integrated DC power system, the preponderance of power converters connecting several loads with power ranging from (W) to (MW) levels rises additional concerns about the effects of a DC fault on other loads connected to the same bus or adjacent buses. Equally critical are the interactions between these power converters during the fault isolation and clearance process. In order to address some of these issues a basic but relevant model has been constructed to study the behavior and effects of DC faults in an MVDC power system for an all-electric ship. Results of the analysis are presented.
Analysis of the Power Quality Impact of Multiple Directed Energy Loads on an Electric Ship Power System
(2010-06) Hebner, R. E.; Gattozzi, A. L; Cohn, K. R; Colson, W. B.
The electrical power system of an all-electric ship has been modeled in Simulink for the case of a ship supporting several high power directed energy loads, among which are a Free Electron Laser (FEL), an Active Denial System (ADS), and a Laser Weapon System (LaWS). Starting from a load centered approach, and a physical description of the components of the various loads, individual models of each load plus a combined model for a system supporting simultaneously one instance of all loads have been developed. Sample case studies are presented corresponding to expected operational scenarios for a US Navy ship and to potential emergency conditions. The models have been designed to be interactive, allowing the operator to change key settings dynamically while the simulation is running, thus mimicking an actual operation of the power system on a ship in real time. A preliminary graphical user interface has also been developed to demonstrate the ability of these models to be converted into top-level training tools for Navy personnel supported by a realistic representation of the ship power system.
Analytical Description of a Series Fault on a DC Bus
(IEEE, 2012-01) Gattozzi, A.L.; Herbst, J.D.; Uriarte, F.M.; Hebner, R.E.
The solution of the equations of a dc circuit containing an arc is given and compared with experimental data. The arc is modeled according to its classical equivalent circuit and the adequacy of this model is discussed. The analytical solution for the circuit with an opening gap is given for the case of a constant gap and the results are extended to the cases of a gap opening with uniform velocity and a gap opening with constant acceleration, under the assumption of a quasi-static approximation for which the limits of applicability are estimated. Voltage and current evolutions in time are derived, including an estimate of the arc duration and quenching time. The results are compared to experimental data. Also provided is a generalized view of the transient behavior of an arc in a circuit that extends the description commonly used, in terms of only a voltage-current relationship, by also including inductive effects.
Approaches to Shipboard Power Management
(2005-02) Davey, K.R.; Meek, C; Tucker, D; Shutt, B; Hebner, R.E.
Shipboard power grid reconfiguration is a key ingredient for survivability, under adverse conditions, and for efficient grid operation. Two requirements surface if the procedure is to be implemented close to real time. First, the complicated dynamics of the system must be accurately modeled by a simpler equivalent model. Second, a constrained optimization problem has to be solved very rapidly. The second objective's challenge grows exponentially with the number of possible switch states. Both discrete integer optimization techniques and stochastic algorithms have been successfully examined in this regard. A new and promising technique involves partial variable solutions; a subset of the solution space is treated as known and the global solution approached iteratively. The technique shows a 60: 1 speed up in solution on a test grid with 16 million possible configurations.
Assessing Confidence in Parallel Simulation Results
(IEEE, 2013-04) Uriarte, F.M.; Hebner, R.E.
To accelerate the simulation of microgrid behavior, a parallel power system solver is being developed. The solver (CEMSolver) aims to accelerate the simulation of large-scale shipboard power system models created in MATLAB/Simulink with the SimPowerSystems blockset. While speedups of 50x have been reported, there remains insufficient confidence in the simulation results. This paper presents a point-by-point comparison of the results produced by MATLAB/Simulink 2012a and in parallel by CEMSolver. A large shipboard power system model is used for the comparison. It is concluded that, while the results show differences related to integration methods, all reported measurements of instantaneous voltage and current waveforms are within reasonable agreement.
A collaborative early-stage ship design environment
(2012) Chalfant, J.; Langland, B.; Abdelwahed, S.; Chryssostomidis, C.; Dougal, R.; Dubey, A.; El Mezyani, T.; Herbst, J. D.; Kiehne, T.; Ordonez, J.; Pish, S.P.; Srivastava, S.; Zivi, E.
Recent advances in sensor and weapons systems are significantly increasing the electrical power that is required and the thermal loads that must be dissipated onboard US Navy ships. Thus, design tools and methods must bring detailed consideration of all disciplines early in the design process, including electrical, thermal and controls in addition to the traditional naval architecture and marine engineering. Effective interface of the multiple disciplines demands a collaborative design process. The Electric Ship Research and Development Consortium (ESRDC) has developed the backbone structure of a collaborative design environment with the goal of bringing together many disciplines early in the ship design process. This design environment brings many innovations, especially in the arena of simultaneous collaborative design. This paper describes the Smart Ship System Design (S3D) environment as developed to date, along with overall and discipline-specific visions of implementation of the environment in ship design.
Coordination of large pulsed loads on future electric ships
(IEEE, 2007-01) Domaschk, L.N.; Ouroua, A.; Hebner, R.E.; Bowlin, O.E.; Colson, W.B.
Part of the technical versatility of future all-electric ships is the potential ability to share large amounts of power among a variety of high-power loads. To help evaluate this potential and to provide information to help guide technology selection, a physics-based model of a power train for an electric ship has been developed and implemented on three modeling platforms. Using this model, three different investigations have been carried out to explore aspects of the behavior of a rotating machine power source for a shipboard rail launcher. These were: 1) influence of rapid charging of the rotating machine system on the ship power system; 2) use of the stored energy in the rotating machines to improve ship power quality; and 3) use of the stored energy in the rotating machines to power a pulsed free-electron laser. Each study highlighted different integration opportunities and challenges. The first showed that, because the charging of the rail launchers was through 5-MW motors, there could be a voltage sag for a few cycles, but this could easily be managed so that the sag could be reduced to an inconsequential level. The second study showed that, with appropriate power electronics, the stored energy in the rail launcher power supply can be used to correct power quality problems introduced by other ship systems. Finally, the stored energy in the launcher power supply can be used to fire a free electron laser for ship defense. This feature opens the possibility of routine operation of the entire ship at highest efficiency, i.e., with the smallest number of gas turbines operating near full power, while providing stored energy needed for ship defense
Cross-platform validation of notional baseline architecture models of naval electric ship power systems
(2011) Ali, H.; Dougal, R; Ouroua, A; Hebner, R; Steurer, M; Andrus, M; Langston, J; Schoder, K; Hovsapian, R.
To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.
A dc arc model for series faults in low voltage microgrids
(IEEE, 2012-12) Uriarte, F.M.; Gattozzi, A.L.; Herbst, J.D.; Estes, H.B.; Hotz, T.J.; Kwasinski, A.; Hebner, R.E.
This paper presents a dc arc model to simplify the study of a critical issue in dc microgrids: series faults. The model is derived from a hyperbolic approximation of observed arc voltage and current patterns, which permit analyzing the arc in terms of its resistance, power, energy, and quenching condition. Recent faults staged by the authors on a dc microgrid yielded enough data to develop an arc model for three fault types: constant-gap speed, fixed-gap distance, and accelerated gap. The results in this paper compare experimental and simulation results for the three fault types. It is concluded that because the instantaneous voltage, current, power, and energy waveforms produced by the model agree well with experimental results, the model is suitable for transient simulations.
Design and analysis of a 20 MW propulsion power train
(2004-03) Beno, J.H.; Flynn, M.M.; Hayes, R.J.; Hebner, R.E.; Jackson, J.R.; Ouroua, A.; Pichot, M.A.; Schroeder, E.; Zierer, J.J.; Weeks, D.A.
The electric ship research program at the University of Texas at Austin focuses on the development of power system technology for future electric ships. The main goal of the on-going research activity is to identify critical, high pay-off technology development needed to enable major improvement, in size and functionality, of navy ships power systems. Initial efforts were directed towards the establishment of a baseline power train which highlights various constraints and provides a basis for later optimization efforts. A 20 MW power train system was chosen for such a baseline, and all components, from fuel to propulsion motor, were considered and their impact on the whole power system assessed. The baseline design consists of a 25 MVA/3600 rpm radial flux permanent magnet generator, a 22 MVA PWM converter, and a 20 MW/150 rpm radial flux permanent magnet motor, along with the amount of fuel sized for an assumed mission profile, and the widely used LM2500 gas turbine. The analysis shows that fuel is by far the dominant component contributing to weight and volume and, consequently, overall efficiency of power train components is the most relevant parameter to reduce weight and volume. The 3600 rpm generator is the smallest component. The 150 rpm motor is the heaviest component, other than fuel, weighing close to 100 tonnes.
Designing Pulse Power Generators
(IEEE, 2005-08) Davey, K.R.; Uglum, J.R.
When the performance criteria for a pulsed power generator is power density, and the duty cycle remains short ( s), then copper coils with an exciter are favored over permanent magnet rotors. If the permanent magnets are replaced with copper coils, steel, and an exciter, with the same total weight, the copper coil alternative will return a higher magnetomotive force/weight, and thus a higher power density system. A variable metric optimization is completed for a generator, assuming the objective is to charge a capacitor bank. The equations governing allowed current density in capacitor charging applications and alternating current/direct current (ac/dc) resistance ratios are derived.
Development and analysis of trapped field magnets in electromechanical devices
(0000-00-00) Davey, K.; Wienstein, R.; Sawh, R.
High temperature superconducting trapped field magnets (TFM) offer great potential as an alternative to 2>d generation YBCO wire, both in cost and performance. Attention is given to the calculation of current distribution within YBCO disks at partial and full activation and comparing this to experimental values. The best results are obtained by treating the current as a sequence of nested current rings. The fields are computed by integrating the elliptic integrals representing the fields from these rings and using variable metric optimization to choose the ring radii to best match the activation field over the on-activated material. A technique for treating the sub-regions of the TFM as voltage fed coils appears most expeditious for computing forces.
Development of a Multicore Power System Simulator for Ship Systems
(2011-04) Uriarte, F.M.; Hebner, R.E.
An important impediment to using widely available software to simulate the behavior of advanced power systems for electric ships is that the simulation time is too long to be practical. Consequently, the Center for Electromechanics at the University of Texas at Austin (UT-CEM) is developing a multicore power system solver to simulate large shipboard power systems. In its first year of development, the focus is on testing CEM’s solver (CEMS) for accuracy. This paper presents an overview of the major traits of CEMS, and compares its simulation results to the well-known commercial power system simulator SimPowerSystems. Preliminary results show that accuracy is maintained and improved in specific test cases.
Development of Electric Propulsion Motors with Integrated Power Electronics
(2004-01) Schroeder, E.; Pichot, M.A; Ouroua, A; Flynn, M.M; Beno, J.H.
The effective integration of electric power in future naval ships requires the development of technologies that allow for volume and mass reduction of critical components. The University of Texas at Austin Center for Electromechanics is studying the potential for volume and mass reduction through the integration of power electronics into an electric propulsion motor. Two conceptual designs of a motor with integrated power electronics are presented. Integration of power electronics into the motor frame offers space saving advantages, allowing the motor and power electronics to share the same housing and cooling system. Accordingly, significant mass and volume reductions are possible in the power electronics housing and cooling auxiliaries.
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.
Dynamic Simulations of a Large High-Frequency Power System
(Society for Modeling & Simulation International, 2011) Hebner, R.E.; Beno, J.H.; Ouroua, A.
Dynamic simulations to assess performance aspects of a large high-frequency power system have been conducted. The analysis uses a model of an 80-MW power system for an all-electric ship. The model, developed in the Matlab/Simulink environment, includes several power generation units, two propulsion power trains, an energy storage system, a high-power pulse load, and several service loads. Three case studies were addressed. The first considers the response of the power system to a high-power step load, representing a sudden request for acceleration of the ship. The second deals with the effects of a partial loss of generation during operation. The third addresses the effects of load drop on the power system.
Dynamic thermal modeling and simulation framework: design of modeling techniques and external integration tools
(2009-12) Pierce, Michael Stephen; Kiehne, Thomas M.; Seepersad, Carolyn
In looking to the future of naval warfare, the US Navy has committed itself to development of future classes of an All-Electric Ship (AES) that will incorporate significant technological advancements in the areas of power management, advanced sensor equipment and weaponry, reconfigurability, and survivability systems while simultaneously increasing overall system efficiencies and decreasing the operational costs of the future naval fleet. As part of the consortium responsible for investigating the viability of numerous next-generation technologies, the University of Texas at Austin is dedicated to providing the capabilities and tools to better address thermal management issues aboard the future AES. Research efforts at the University of Texas in Austin have focused on the development of physics-based, dynamic models of components and subsystems that simulate notional future AES, system-level, thermal architectures. This research has resulted in the development of an in-house thermal management tool, known as the Dynamic Thermal Modeling and Simulation (DTMS) Framework. The work presented herein has sought to increase the modeling capabilities of the DTMS Framework and provide valuable tools to aid both developers and users of this simulation environment. Using numerical approximations of complex physical behaviors, the scope of the DTMS Framework has been expanded beyond elements of thermal-fluid behaviors to capture the dynamic, transient nature of far broader, more complex architectures containing interconnected thermal-mechanical-electrical components. Sophisticated interfacial systems have also been developed that allow integration of the DTMS Framework with external software products that improve and enhance the user experience. Developmental tools addressing customizable presentation of simulation data, debugging systems that aid in introduction of new features into the existing framework, and error-reporting mechanisms to ease the process of utilizing the power of the simulation environment have been added to improve the applicability and accessibility of the DTMS Framework. Finally, initial efforts in collaboration with Mississippi State University are presented that provide a graphical user interface for the DTMS Framework and thus provide far more insight into the complex interactions of numerous shipboard systems than would ever be possible using raw numerical data.
Effects of EM weapons requirements on the electric ship power system
(2004-06) Beno, J.H.; Ouroua, A; Flynn, M.
The electric ship research effort at the University of Texas, Center for Electromechanics, is presently focusing on the development of a comprehensive model of ship power system. The model will allow the study of various architectures and power system configurations. The power system performance is assessed under prescribed scenarios that include representative mission profiles, advanced technologies in various system components, and fault mitigation. Particular attention will be given to the interaction of EM weapons with the whole power system and their effects on system stability. The potential benefits of an auxiliary energy storage system for EM weapons will be investigated. Initial analyses results will be presented.
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.