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ABSTRACT: This letter presents an extended Mayr's equation-based model for the pantograph detachment arc of the high-speed railway traction system. The proposed model is composed of Mayr's model for arc behavior control and time-controlled switches for starting pantograph detachment and reattachment events, which are developed by MODELS language and TACS in Electromagnetic Transients Program/Alternate Transients Program. With the combination of a traction motor drive circuit, an effective simulation is performed to observe the harmonic spectrum of pantograph current that is caused by pantograph detachment arcs. By comparing this with the actual measurements for validation, it shows that the proposed arc model is useful for estimating the harmonic frequency range of the pantograph arc current and for power-quality studies.
IEEE Transactions on Power Delivery 08/2010; · 1.35 Impact Factor
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ABSTRACT: This paper presents a new procedure to track the disturbance source location of voltage sags and shunt capacitor switching transients in a power system based on branch current measurements. In the proposed method, the power-quality metering locations are first determined by the sensitivity of the system fault-current level to the fault voltage. Then, a current deviation index for representing the change of each measured branch current rms magnitudes before and after the disturbance is calculated to track the disturbance source location within an area confined by the directions of the top-priority branches. The IEEE 30-bus benchmark system and an actual transmission system with recorded power-quality disturbance events are used to illustrate the usefulness of the proposed method. Simulation results obtained by the proposed method are also compared with those obtained by a previously developed approach and by actual recorded data. By observing the results, it shows that the proposed method is efficient and accurate to track the source area of voltage sags or shunt capacitor switching transients.
IEEE Transactions on Power Delivery 11/2008; · 1.35 Impact Factor
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ABSTRACT: The purpose of this paper is to search for the optimal connection of power transmission lines with underground power cables for a newly constructed substation to reduce the magnetic flux density around it. The genetic algorithm method is employed for solving the problem of optimization mentioned above to get a best connection. With the optimal connection, the magnetic flux density can be reduced effectively without spending or utilizing extra time, manpower, and equipment.
IEEE Transactions on Power Delivery 08/2008; · 1.35 Impact Factor
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ABSTRACT: The black-box arc models are commonly used for describing the interaction between a switching arc and the surrounding circuit during a circuit breaker interruption process. This paper proposes an extended Mayr's equation based arc model for the SF<sub>6</sub> circuit breaker to characterize the transients associated with switching off a shunt reactor. The proposed model includes Mayr's arc model with estimated parameters input, a time-controlled switch, and a dielectric recovery voltage control unit. From the transient simulation aspects, the paper not only provides the guidelines for estimating parameters required for Mayr's equation to simulate the arc dynamics, but also describes a method for modeling post-arc behavior that cannot be simulated by conventional black-box models. Several study cases are performed to show the usefulness of the proposed model. Results obtained are compared with the measured and calculated data. It shows that the proposed SF<sub>6</sub> circuit breaker arc model is relatively accurate for characterizing the shunt reactor switching transients.
IEEE Transactions on Power Delivery 08/2007; · 1.35 Impact Factor
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ABSTRACT: Transient overvoltages encountered by the power system equipment are mainly divided into three types: lightning surges, switch surges, and power frequency overvoltages. This paper presents a transient overvoltage study in a 345 kV hybrid overhead and underground transmission system that serves a high-tech industrial park. Based on the actual system information, the distributed parameter model is adopted to create a 345 kV transmission network in EMTP/ATP for simulations. The high- energy phenomenon and lighting surges are included in the transient study. Then, major criteria suggested by IEEE and IEC standards are used to assess the level of insulation coordination of the hybrid overhead/underground high-voltage system.
Power Engineering Society General Meeting, 2007. IEEE; 07/2007
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ABSTRACT: Power cable capacitance is used to provide data for research and development, engineering design, quality control, and acceptance or rejection under specifications. This study aims at calculating the XLPE cable capacitance effects of semi-conductive layer with various permittivity values. Factors under consideration of calculating the cable capacitance includes the dielectric constant, diameter, and thickness for presenting "equivalent capacitance" and estimation. The usefulness of the paper is to show the factors which affect the cable capacitance and can be used for specifying the correct value for cable capacitance to set the production control rules for capacitance deviation control.
Power System Technology, 2006. PowerCon 2006. International Conference on; 11/2006
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ABSTRACT: The transients generated by switching off the shunt reactor via a SF<sub>6</sub> circuit breaker may cause power quality problems in the transmission system. In traditional analyses, the shunt reactor switching simulation usually uses an ideal switch model instead of a more realistic model. As a result, such ideal switch model cannot reflect the actual transient phenomena caused by the energy interaction between contacts of the circuit breaker. In the study, a practical SF<sub>6</sub> circuit breaker model which is in combination of Mayr's arc model, EMTP TACS switch control with dielectric strength control, and a voltage comparator is proposed to simulate the switching process of the shunt reactor and to observe the associated transient behaviors. Two test cases are performed to validate the usefulness of the proposed model. In comparing with the estimated and measured data, simulation results show that the proposed circuit breaker model is relatively accurate to predict the shunt reactor switching transients.
Power System Technology, 2004. PowerCon 2004. 2004 International Conference on; 12/2004
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ABSTRACT: This paper presents a study on controlling electrical stress of high-voltage underground cables by semi-conductive shielding. Except impurities and cavities of the insulation material, most high-voltage underground cable insulation failures are caused by unusual energy dissipation conditions on the interface of insulation and semi-conductive layers. This paper investigates the principles of using semi-conductive shielding to control electric flux distribution and to constrict voltage between the shielding and the surface of insulation layer. In addition, termination fault analysis and study cases for using electrical stress control devices are also presented to show how the semiconductive shielding can be used to mitigate the nonuniformly distributed high electrical stress and to improve the voltage withstand level of the insulation layer.
Transmission and Distribution Conference and Exhibition 2002: Asia Pacific. IEEE/PES; 11/2002
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ABSTRACT: The purpose of this paper is to present a new approach for prediction of harmonic currents generated by a cluster of six-pulse converters with randomly varying loads. The proposed method models multiple converters based on an equivalent-circuit approach and uses a statistical analysis to obtain the probabilistic model of harmonic currents generated by the converters. The effects of ripples at the converter DC side also can be taken into account in the proposed approach. Monte Carlo simulation is then employed to validate the obtained probabilistic model of harmonic currents. The proposed approach is tested with a system including a cluster of converters. Simulation results show that the proposed approach is simple, effective, and computationally robust.
Harmonics and Quality of Power, 2002. 10th International Conference on; 11/2002
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ABSTRACT: Power quality is a growing concern to both electric utilities and their customers. Among the commonly seen nonlinear loads, electric arc furnaces (EAFs) in the steel plant play important roles that cause power quality disturbances. The nonlinear characteristics of the EAF generate significant harmonic currents and flickers flowing through the plant and the utility power system. This paper presents a harmonic analysis for a steel plant with an ac EAF load. Simulation results obtained by using Matlab/Simulink are then validated by the actual measuring data. It is shown that the simulation model including the power network and the EAF load is relatively accurate in comparing with the actual field measurements
Power Engineering Society General Meeting, 2006. IEEE;
