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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/Simulink™, EASY5™, or ACSL™.

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.

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 modelling 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.

In this paper, a new control strategy is proposed which is simple in structure and has the straightforward goal of minimizing the stator current amplitude for a given load torque. It is shown that the resulting induction motor efficiency is reasonably close to optimal and that the approach is insensitive to variations in rotor resistance. Although the torque response is not as fast as in field-oriented control strategies, the response is reasonably fast. In fact, if the mechanical time constant is large relative to the rotor time constant, which is frequently the case, the sacrifice in dynamic performance is insignificant relative to FO strategies.

In this paper, a recently-developed algorithmic method of deriving the state equations of power systems containing power electronic components is described. Therein the system is described by the pertinent branch parameters and the circuit topology; however, unlike circuit-based algorithms, the difference equations are not implemented at the branch level. Instead, the composite system state equations are established. A demonstration of the computer implementation of this algorithm to model a variable-speed, constant-frequency aircraft generation system is described. Because of the large number of states and complexity of the system, particular attention is placed on the development of a model structure which provides optimal simulation efficiency.

Design-oriented stability criteria are developed for ac power systems with regulated electronic loads. The systems are assumed to contain rotating machines as well as regulated solid-state switching power converters. The system models are developed such that the generalized Nyquist and Bode techniques are possible. Then small-disturbance stability criteria are set forth. The stability constraints are simplified and formulated in terms of different subsystem matrix input impedance norms. An example system is analyzed using the proposed techniques. A comparison with time domain simulations and eigenvalue analysis is performed to validate the advanced stability criteria.

The performance of two 20-kHz actuator power systems being built for an advanced launch system are evaluated for a typical launch scenario using an end-to-end system simulation. Aspects of system performance ranging from the switching of the power electronic devices to the vehicle aerodynamics are represented in the simulation. It is shown that both systems adequately stabilize the vehicle against a wind gust during a launch. However, it is also shown that in both cases there are bus voltage and current fluctuations which make system power quality a concern.

The performance of a resonant dc link based actuator power system being built for an advanced launch system application is evaluated for a typical launch scenario using two end-to-end system simulations, one using a digital computer and the other using a hybrid computer. Aspects of system performance from the switching of the power electronic devices to the vehicle aerodynamics are addressed. Using these simulations, it is shown that the resonant dc link actuator adequately stabilize the vehicle against a wind gust during a launch.