J. Jatskevich, O. Wasynczuk, S. D. Pekarek, Purdue University; C. E. Lucas, E. A. Walters, PC Krause and Associates, Inc. In the analysis of power-electronic-based energy conversion systems, it is important to identify the operational modes of the associated converters and inverters. However, as the number of switching elements increases, it becomes more difficult to analytically establish all possible modes of operation. In this paper, a modeling technique is described wherein a state-space representation of the overall system is generated automatically and updated dynamically as each new topology is encountered. Utilizing this approach, it becomes possible to identify the operational modes of converters and inverters based upon the cyclically repeated sequences of topologies that can be observed during steady-state operation. To demonstrate this technique, an example system comprised of a 6-phase synchronous machine, rectifier, and interphase transformer is considered. This system exhibits several distinct modes of operation that depend upon specific circuit connections. These operating modes are automatically identified using the proposed methodology and the results are compared with measured dynamic performance. SAE Transactions Journal of Aerospace, sec. 1, set 3, Month, 2000, pp....
Read MoreAn Observer-Based Automated Averaging Technique for Power Electronic Circuits
E. A. Walters, O. Wasynczuk, J. V. Jatskevich, C. E. Lucas, PC Krause and Associates, Inc. Average-value models are commonly used in the design and analysis of power electronic-based systems as a method of portraying the overall system dynamics while neglecting discontinuities that arise from switching. Although numerous averaging methodologies have been developed to eliminate discontinuities, they are typically limited to specific circuits operating in specific modes. Therefore, substantial analytical effort is generally required to select an appropriate averaging technique and develop the corresponding average-value model that is valid for a given converter. To reduce this effort, an automated averaging technique is set forth in which an averaged model is established via coupling with a detailed simulation of the system. The structure of the averaged model is based upon state-space averaging with the detailed simulation used to calculate state models for each switching topology, the time spent per cycle in each topology, and the operating mode (continuous or discontinuous) of the circuit. However, since classical state-space averaging is not applicable to circuits with state-dependent switching logic and does not portray high- frequency dynamics associated with discontinuous states, a state feedback loop is introduced such that the high-frequency dynamics associated with state- dependent switching or discontinuous modes are accurately portrayed. To demonstrate the new technique, to example systems are examined, a PWM-controlled buck converter operating in both continuous and discontinuous modes and buck converter with a hysteresis current controller. The new averaging technique is verified by comparison with established analytical and numerical methods. SAE Transactions Journal of Aerospace, sec. 1, set 3, Month 2000, pp....
Read MoreDistributed Simulation of Electric Power Systems
J. Jatskevich, O. Wasynczuk, N. Mohd Noor, Purdue University; E. A. Walters, PC Krause and Associates, Inc; C. E. Lucas, Purdue University; P. T. Lamm, U.S. Air Force Research Laboratory Recent advancements in computer networking have enabled the interconnection of inexpensive desktop computers to form powerful computational clusters that can be effectively utilized when simulating electric power systems. In order to maximize the computational gain, it is necessary to identify the computational tasks that can be performed concurrently and to optimally distribute those tasks among the available processors. In this paper, the electrical power system is viewed as a collection of interconnected dynamical subsystems each described by a set of differential/algebraic equations. The tasks that can be performed concurrently are identified and a new approach of optimally distributing the corresponding calculations is set forth. The effectiveness of the proposed approach is demonstrated by distributing a detailed simulation of the Western System Coordinating Council (WSCC) three machine nine-bus system on an SCI-based network composed of three personal computers. The simulation includes the effects of network and stator transients. Using the Runge-Kutta-Fehlberg integration algorithm, a 206% improvement in simulation speed was achieved. Proceedings 14th Power Systems Computation Conference, June 24-28, 2002, Sevilla,...
Read MoreA Distributed Heterogeneous Simulation of a Representative Aircraft Power System
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 MoreReal-Time Distributed Simulation of DC Zonal Electrical Distribution System
J. Jatskevich, C. E. Lucas, E. A. Walters, O. Wasynczuk, PC Krause and Associates Inc; E. L. Zivi, U.S. Naval Academy In this paper, a prototype DC Zonal Electrical Distribution System (ZEDS) developed under the Naval Combat Survivability effort is considered. A model of one zone is described in detail on a component level, and is viewed as a collection of interconnected dynamical subsystems each described by a set of state equations. An innovative approach for distributing the subsystems among multiple computers is shown to result in a significant improvement in simulation speed. Moreover, when Average Value Models (AVMs) replace the detailed converter models, a faster than real-time simulation can be achieved. 2002 SAE Power Systems Conference, October 29-31, 2002, Coral Spring, FL. Paper...
Read MoreDistributed Heterogeneous Simulation of Large-Scale Dynamical Systems
C. E. Lucas, E. A. Walters, J. Jatskevich, O. Wasynczuk, PC Krause and Associates, Inc; E. Zivi, U.S. Naval Academy 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. For the purpose of demonstration, this technique is applied to a detailed simulation of a representative naval 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. 13th Ship Control Systems Symposium, April 7-9, 2003, Orlando,...
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