C. E. Lucas, E. A. Walters, J. Jatskevich, O. Wasynczuk, PC Krause and Associates, Inc; P. T. Lamm, U.S. Air Force Research Laboratory In this paper, a new technique useful for the numerical simulation of large-scale systems is presented. This approach enables the overall system simulation to be formed by the dynamic interconnection of the various interdependent simulations, each representing a specific component or subsystem such as electrical, mechanical, hydraulic, or thermal. Each simulation may be developed separately using possibly different commercial-off-the shelf simulation programs thereby allowing the most suitable language or tool to be used based on the design/analysis needs. For the purpose of demonstration, this technique is applied to a detailed simulation of a representative aircraft power system. This system is comprised of ten component models each developed using MATLAB/SimulinkTM, EASY5TM, or ACSLTM. When the ten component simulations were distributed across just four personal computers (PCs), a greater than 15-fold improvement in simulation speed (compared to the single-computer implementation) was achieved. 2002 SAE Power Systems Conference, October 29-31, 2002, Coral Spring, FL. Paper...
Read MoreCommunication Interval Selection in Distributed Heterogeneous Simulation of Large-Scale Dynamical Systems
C. E. Lucas, E. A. Walters, J. Jatskevich, O. Wasynczuk, PC Krause and Associates, Inc; P. T. Lamm, U.S. Air Force Research Laboratory In this paper, a new technique useful for the numerical simulation of large-scale systems is presented. This approach enables the overall system simulation to be formed by the dynamic interconnection of the various interdependent simulations, each representing a specific component or subsystem such as control, electrical, mechanical, hydraulic, or thermal. Each simulation may be developed separately using possibly different commercial-off-the-shelf simulation programs thereby allowing the most suitable language or tool to be used based on the design/analysis needs. These subsystems communicate the required interface variables at specific time intervals. A discussion concerning the selection of appropriate communication intervals is presented herein. For the purpose of demonstration, this technique is applied to a detailed simulation of a representative aircraft power system, such as that found on the Joint Strike Fighter (JSF). This system is comprised of ten component models each developed using MATLAB/SimulinkTM, EASY5TM, or ACSLTM. When the ten component simulations were distributed across just four personal computers (PCs), a greater than 15-fold improvement in simulation speed (compared to the single-computer implementation) was achieved. SPIE 17th Annual International Symposium AeroSense, April 22-25, 2003, Orlando, FL. and SPIE Proceedings Enabling Technologies for Simulation Science VII, vol. 5091, September 4, 2003, pp....
Read MoreDistributed Simulation of an Uninhabited Aerial Vehicle Power System (SAE Paper) and Distributed Simulation (Aerospace Engineering)
Scott Graham, Ivan Wong, Won-Zon Chen, Alex Lazarevic, Keith Cleek, Northrop Grumman Corporation ; E. A. Walters, C. E. Lucas, O. Wasynczuk PC Krause and Associates, Inc; Peter Lamm, U.S. Air Force Research Laboratory Future Air Force intelligence, surveillance, and reconnaissance (ISR) platforms, such as high-altitude Uninhabited Aerial Vehicles (UAV), may drastically change the requirements of aircraft power systems. For example, there are potential interactions between large pulsed-power payloads and the turbine engine that could compromise the operation of the power system within certain flight envelopes. Until now, the development of large-scale, multi-disciplinary (propulsion, electrical, mechanical, hydraulic, thermal, etc.) simulations to investigate such interactions has been prohibitive due to the size of the system and the computational power required. Moreover, the subsystem simulations that are developed separately often are written in different commercial-off-the-shelf simulation programs. In this paper, a new technique useful for the numerical simulation of large-scale systems to overcome these obstacles, known as Distributed Heterogeneous Simulation (DHS), is utilized to form a dynamic system-level simulation of a high-altitude, long-endurance UAV-type of power system. This system includes detailed dynamic models of a turbine engine, high- and low-spool generators, and payloads. Although not necessary, all of the component models for this system were developed within the same simulation environment, specifically with MATLAB/Simulink. This enabled a single-computer integrated system model and a distributed computer system simulation to be formed thereby allowing for a direct comparison of simulation accuracy and computational performance for the two simulation approaches. From this comparison, it was determined that by distributing the system simulation across three computers, a 21-fold increase in simulation speed could be realized while producing nearly identical results. 2004 SAE Power Systems Conference, November 2-4, 2004 Paper #2004-01-3193 and Aerospace Engineering, November 2004,...
Read MoreCross-Platform Distributed Heterogeneous Simulation of a More Electric Aircraft Power System
C. E. Lucas, E. A. Walters, O. Wasynczuk, PC Krause and Associates, Inc; Peter T. Lamm, U. S. Air Force Research Laboratory To support research and analysis requirements in the development of future power systems, a flexible and efficient means of predicting the dynamic performance of large-scale multi-disciplinary systems prior to hardware trials is crucial. With the development of Distributed Heterogeneous Simulation (DHS), the technology now exists to enable this type of investigation. Previously, DHS was shown to allow the interconnection of component simulations running on a single- or distributed-computer network and developed using any combination of a variety of commercial-off-the-shelf software packages for the Microsoft Windows operating system. However, for large-scale systems, all subsystem models may not be developed in software packages operating under Windows thereby requiring a translation of such models in order to incorporate them within a system simulation. In this paper, the DHS technique is expanded to support the UNIX operating system, thus, allowing subsystem models developed and executed on either UNIX- or Windows-based computers to be interconnected to form a dynamic system simulation. For the purpose of demonstration, a more-electric fighter (MEF) power system, such as that found on the Joint Strike Fighter (JSF), has been selected as a study system. This system is comprised of ten component models each developed using MATLAB/Simulink, EASY5, or ACSL. Utilizing the system simulation, studies have been performed to illustrate the dynamic interactions between the subsystems when simulated on a heterogeneous computer network containing both Windows- and Unix-based machines. SPIE Defense and Security Symposium Proceedings, March 2005. Contact information:...
Read MoreAverage-Value Model of a High-Frequency Six-Phase Generation System
Juri Jatskevich University of British Columbia; E. A. Walters, C. E. Lucas, PC Krause and Associates, Inc; Peter T. Lamm U.S. Air Force Research Laboratory In this paper, a parametric average-value modeling approach is applied to a high-frequency six-phase aircraft generation subsystem. This approach utilizes a detailed switch-level model of the system to numerically establish the averaged dynamic relationships between the ac inputs of the rectifier and the dc-link outputs. A comparison between the average-value and detailed models is presented, wherein, the average-value model is shown to accurately portray both the large-signal time-domain transients and the small-signal frequency-domain characteristics. Since the discontinuous switching events are not present in the average-value model, significant gains can be realized in the computational performance. For the study system, the developed average-value simulation executed more than two orders of magnitude faster than the detailed simulation. SAE Transactions Journal of Aerospace, July 2005, pp. xxx, and 2004 SAE Power Systems Conference, November 2-4, 2004, Reno, NV, Paper...
Read MoreAn Algorithm for the Optimal Allocation of Subsystem Simulations within a Distributed Heterogeneous Simulation
C. E. Lucas, E. A. Walters, PC Krause and Associates, Inc; O. Wasynczuk, Purdue University; Peter T. Lamm, U. S. Air Force Research Laboratory An allocation algorithm for optimally assigning the various subsystem simulations, within a distributed heterogeneous simulation, to a specific set of computational resources has been developed. This algorithm uses a cost function that approximates the simulation execution time for each of the subsystems based upon the model complexity and the performance parameters of the available computer resources. The cost function is then evaluated to determine the optimal allocation that ensures the overall simulation execution time is minimized. In this paper, the allocation algorithm is applied to a large-scale power-electronic-based aircraft electrical power system. This study system is comprised of ten component simulations that together are modeled by 85 state variables and include 74 switching devices. Both optimal and sub-optimal allocations are considered and the predicted simulation run times are verified experimentally. SAE Transactions Journal of Aerospace, July 2005, pp. 1871-1878 and 2004 SAE Power Systems Conference, November 2-4, 2004, Reno, NV, Paper #...
Read More