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This paper describes methods and issues related to interfacing electromagnetic transient simulation programs with general mathematical algorithms, which are either custom-developed by the user or are available through other mathematical analysis platforms. Various interfacing types and techniques are described along with potential areas of application. Implementation methods are detailed for each type of interface as well. This paper presents several interfacing examples from a wide variety of applications, including advanced switching schemes for power converters and controller implementation. Index Terms--Electromagnetic transient simulation, interfacing, mathematical algorithms.

This paper presents an approach to the design of robust power-electronic systems (i.e., those which have optimal operation over a range of operating configurations). Designing nonlinear systems, such as power-electronic converters, to be robust is a challenging task as settings that may be optimal for a given operating configuration may be inadequate for another. This paper extends the method of combining nonlinear optimization with electromagnetic transient simulation, which has previously been successfully applied to the design of optimal systems at only one operating point; to an approach which simultaneously considers a range of operating points. The method is exemplified using two examples. In the first example, adc power supply is designed to operate optimally over a range of current order settings. The second is the case of an HVdc system, which is optimized to work well with a range of possible ac system configurations. Index Terms--DC power supply, electromagnetic transient simulation, HVdc transmission, nonlinear optimization, robustness.

Electromagnetic transient simulation programs (emtp-type programs) are powerful tools for the study of a wide range of power system transient problems. This paper introduces a novel tool in which an emtp-type program becomes the objective function evaluator for a nonlinear optimization algorithm. In this approach, the nonlinear optimization program is given control to perform several consecutive runs with a view to minimize (or maximize) the desired objective function, which is computed from the results of each simulation run. Since the optimization algorithm strategically selects the parameters for the emtp run, the overall design process is orders of magnitude faster than that possible from sequential or random (Monte-Carlo-type) multiple-runs of the emtp-type program. The paper discusses the mechanics of the interface as well as design of objective functions. The power of the proposed method is demonstrated through two examples for the design of power-electronic converters. Index Terms--dc-dc converter, optimal pulse-width modulation (PWM), optimization, transient simulation, voltage-sourced converter.

Electric power distribution systems of many commercial and industrial sites often employ variable frequency drives and other loads that internally utilize dc. Such loads are often based on front-end line-commutated rectifiers. The detailed switch-level models of such rectifier systems can be readily implemented using a number of widely available digital programs and transient simulation tools, including the Electromagnetic Transient (EMT)-based programs and Matlab/Simulink. To improve the simulation efficiency for the system-level transient studies with a large number of such subsystems, the so-called dynamic average models have been utilized. This paper presents the average-value modeling methodologies for the conventional three-phase (six-pulse) front-end rectifier loads. We demonstrate the system operation and the dynamic performance of the developed average models in discontinuous and continuous modes, as well as under balanced and unbalanced operation. [ABSTRACT FROM PUBLISHER]