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Your search keyword '"Shahrtash, S. Mohammad"' showing total 37 results
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37 results on '"Shahrtash, S. Mohammad"'

10. Passivity enforcement using an infeasible-interior-point primal-dual method

Author

Porkar, Babak, Vakilian, Mehdi, Iravani, Reza, and Shahrtash, S. Mohammad

Subjects
Electric power systems -- United States, Electric power systems -- Management, Electric power systems -- Equipment and supplies, Convex functions -- Evaluation, Quadratic functions -- Evaluation, Mathematical optimization -- Research, Company business management, Business, Electronics, Electronics and electrical industries
Abstract

Application of the network equivalent concept for external system representation in electromagnetic transient studies is well known. However, the challenge in application of an equivalent model, approximated by rational functions, is to guarantee passivity of the corresponding model. Therefore, there is a need to enforce passivity of the equivalent model. In this paper, the passivity enforcement problem is first formulated as a quadratic programming (QP) problem, and then solved based on an efficient implementation, using an infeasible-interior-point primal-dual method. An application of this method for passivity enforcement of a six-port admittance model (with large passivity violations) demonstrates its effectiveness and computational efficiency. Index Terms--Convex quadratic optimization problem, infeasible-interior-point primal-dual method, network equivalent, passivity enforcement.

Published
2008

35. Transient-Based Fault-Location Method for Multiterminal Lines Employing S-Transform.

Author

Ahmadimanesh, Alireza and Shahrtash, S. Mohammad

Subjects
*MULTITERMINAL networks, *SIMULATION methods & models, *ELECTRIC currents, *ELECTRIC faults, *TRANSIENT analysis
Abstract

In this paper, a novel method for fault location in multiterminal transmission lines is presented. The method is based on applying the S-transform to the modal components of synchronized measured currents at different terminals to extract time of arrival of the first arrived transient wave generated by the fault. These arrival times are then reported to a central processor where they are converted to distance indices and involved in a decision procedure. The simulation results have shown good performance of the proposed method under different fault resistances, fault inception angles, fault locations (even on tap points), fault types, and faulted sections. [ABSTRACT FROM PUBLISHER]

Published
2013
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37. Comprehensive 3-capacitors model for partial discharge in power cables.

Author

Haghjoo, Farhad, Khanahmadloo, Esmaeel, and Shahrtash, S. Mohammad

Subjects
ELECTRIC cables, ELECTRIC circuits, INTEGRATED circuits, REDUCED instruction set computers, ELECTRONIC circuits, MICROELECTRONICS
Abstract

Purpose |!|#8211; The paper proposes and presents a comprehensive and integrated circuit model for investigating the behaviour of partial discharges occurring in voids inside the solid insulations of medium and high voltage cables. Design/methodology/approach |!|#8211; The model is based on the well-known three capacitors model, which is remarkably improved to handle physical parameters such as cavity size, position, shape and pressure, environmental parameters such as cable temperature, in addition to operational parameters such as the contributions of the avalanche of free electrons inside the cavity through considering stochastic time delays. Findings |!|#8211; A complete, flexible and reliable model for partial discharges in voids inside the solid insulation of medium and high voltage cables is presented whose output agrees with experimental reported results. Research limitations/implications |!|#8211; The proposed model deals only with single voids, and the semiconductor layers in the insulation of cables are not considered. Practical implications |!|#8211; The model can be used in different physical, environmental and operational conditions in order to investigate the characteristics of partial discharge signals to be used as the bases for partial discharge detection and classification in power cables. Originality/value |!|#8211; This paper presents a novel comprehensive and integrated circuit model with controlling functions to propose the behaviour of partial discharge occurring in voids inside the solid insulation of power cables. The model provides the contribution of geometrical parameters of the void, and operational conditions such as cable temperature and source frequency in partial discharge analysis. [ABSTRACT FROM AUTHOR]

Published
2012
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