S. D. Pekarek, O. Wasynczuk, Purdue University; E. A. Walters, J. V. Jatskevich, C. E. Lucas, N. Wu, PC Krause and Associate, Inc; P. T. Lamm, U.S. Air Force Research Laboratory A novel multi-rate method of simulating power-electronic-based systems containing a wide range of time scales is presented. In this method, any suitable integration algorithm, with fixed or variable time-step, can be applied to the fast and/or slow subsystems. The subsystems exchange coupling variables at a communication interval that can be fixed or varied dynamically depending upon the state of the system variables. The proposed multi-rate method is applied to two example power systems that include power-electronic subsystems. Increases in simulation speed of 183-281% over established single-rate integration algorithms are demonstrated. IEEE Transactions on Power Systems, vol. 19, no. 1, February 2004, pp....
Read MoreDistributed Heterogeneous Simulation, a New Paradigm for Simulating Integrated Naval Power 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; T. E. Neeves, Naval Surface Warfare Center A new paradigm for simulating large-scale dynamical systems is described and applied to an integrated naval power system. This approach enables the overall system simulation to be formed as an interconnection of interdependent dynamic simulations, each representing a specific electrical, mechanical, hydraulic, and/or thermal component/subsystem. Each simulation may be developed independently 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. The proposed simulation paradigm is applied to an advanced naval electric power system that includes a zonal dc electric distribution system and an integrated electric generation and propulsion system. The composite system simulation is implemented on a three-computer network of personal computers by interconnecting simulations of the constituent subsystems. It is shown that significant improvements in computational speed are achieved using this approach. WSEAS/IASME Transactions, issue 3, vol. 1, July 2004, pp....
Read MoreSynchronous Generator-Rectifier Average-Value Modeling for a Naval Electric Power System
Juri Jatskevich, University of British Columbia; E. A. Walters, C. E. Lucas, PC Krause and Associates, Inc. A prototype Integrated Power System that is representative of advanced power systems of future warships is considered. This system is comprised of an AC Generation and Propulsion System as well as a DC Zonal Electrical Distribution System. Obtaining accurate average-value models of individual subsystems that can be used for extracting the input/output impedance as well as for increasing the simulation speed of the respective models. In this paper, a parametric approach for developing a dynamic average-value model of a generator-rectifier subsystem is presented. The method initially requires a detailed switched model from which the rectifier/dc-link dynamics are captured using numerical averaging; however, the resulting model is continuous and computationally efficient. The developed average-value model is compared against measured and detailed simulation results and is shown to be very accurate in both the time- and frequency-domains. A 74-fold increase in simulation speed is achieved. WSEAS/IASME Transactions, issue 3, vol. 1, July 2004, 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 MoreAutomated Average-Value Modeling of Power Electronic Sources and Loads
N. Wu, O. Wasynczuk, Purdue University; E. A. Walters, C. E. Lucas, PC Krause and Associates, Inc; Peter T. Lamm, U.S. Air Force Research Laboratory Power systems that include regulated power-electronic sources and/or loads are susceptible to potentially destabilizing interactions between these components. A variety of techniques and methodologies have been developed to characterize the small- and large displacement stability of such systems. Perhaps the most common approach is to establish the input/output impedance-versus-frequency characteristics of all sources and loads, whereby Nyquist- and/or Bode-inspired criteria may be used to characterize interconnected system stability. Essential to this methodology is a means of accurately and efficiently determining the input and/or output impedance-versus-frequency characteristics of the power electronic components that comprise the overall system. These frequency-domain characteristics can be established by (1) direct measurement, (2) exercising detailed simulations, or, more commonly, (3) using state-space average-value models. The primary disadvantage of using direct measurements is that the hardware must be available a-priori which makes it difficult and/or expensive to change or tailor the impedance characteristics if instabilities occur. Calculation of the impedance characteristics from detailed simulations is generally time consuming, especially if the low-frequency characteristics are needed, and little insight is gained as to how the impedance characteristics are affected by the various design parameters. Average-value models overcome the previous disadvantages; however, they introduce a new one. In particular, the derivation of an average value models is typically time consuming, especially if the circuit topology is complex and/or the power converter exhibits multiple load-dependent modes of operation. In this paper, an automated approach of establishing average-value models of power electronic converters of arbitrary complexity is set forth. The user-supplied inputs consist of a standard Spice-like circuit description (branch parameters and network graph) whereupon the input/output impedance-versus frequency characteristics are automatically and rapidly established. In addition to eliminating the need for the analytical derivation of average-value models, this technique readily permits the inclusion of secondary effects such as conduction losses, switching losses, and magnetic nonlinearities, to name a few. This technique has been successfully applied to characterize the output impedance of a one-quadrant dc/dc buck converter and a three-phase generator/rectifier source. Proceedings 3rd International Energy Conversion Engineering Conference, August 15-18, 2005, San Francisco,...
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