• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.29-37
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• 2006

High speed electric trains have nonlinear loads including converters and inverters for the control synchronous motors. Harmonics produced by these devices are large, but also have noticeable time varying characteristics. Since the large loads are supplied from the power system grid, it must be recognized that not only will the system of utility be impacted, but neighboring customer system could be impacted as well. In this paper time-varying harmonics for high speed electric train loads are measured and evaluated by international harmonic standards IEEE Std. 519 and IEC 61000-3-6 using a cumulative probablistic approach.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.71-77
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• 2007

High speed electric trains have time-varying nonlinear loads causing voltage fluctuations to the power system. A cumulative probablistic approach is the most commonly used method to solve time varying loads. Flicker can be defined as the effect produced on the human visual perception by a changing emission of light lamps subjected to magnitude fluctuations of their supply voltage. This paper provides an in depth analysis on harmonics and flickers measurement of the high speed electric train loads. And the measurement results are evaluated by the IEC 61000-3-6 and IEC 61000-3-7.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.35-42
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• 2006

Large steel industries have nonlinear loads including electric arc furnaces. These nonlinear loads generate harmonic currents and create distortions on the sinusoidal voltage of the power system. This paper provides an in depth analysis on harmonics field measurement of the electric arc furnace loads, adding a single-tuned filter at the customer bus for reducing harmonic distortion and harmonics assessment by the international harmonic standards IEC 61000-3-6 and IEEE Std. 519. The EDSA program was used as a simulation tool for the case study.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.218-219
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• 2006

This paper is about modeling on 1500V DC electric railroad system. Electric railroad systems have peculiar characteristics against other electric system. The characteristics arc that the railroad systems have electric vehicle loads which are power-varying and location-varying with time. Because of this load characteristic, the electric railroad system modeling which reflects its own characteristics on EMTDC simulation could not be achieved. However, to reflect load characteristic on EMTDC, this paper suggests electric railroad system modeling by using TPS (Train Performance Simulator) that was developed in Korea Railroad Research Institute. A TPS program has various kinds of input data, such as operation condition, vehicle condition, and power system condition. By these data, TPS calculates mechanical power consumption and location, especially it decide electric power consumption on the basis of the fact that consumed electric and mechanical power are equal. Moreover, on this paper, movement of vehicle is reflected on EMTDC simulation as variation of feeder impedance. Also, an electric vehicle load is modeled as time-varying constant power load model.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1234-1235
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• 2011

A DC Power Distribution Systems(DC PDS) are widely used in telecommunication system, electric vehicle, aircraft, military system, etc. In the DC PDS, DC bus voltage instability may be occurred by the operation of multiple loads such as pulsed power load, motor drive system, and constant power loads. To damp the transients of the DC bus voltage, the Voltage Bus Conditioner(VBC) with the PI compensator is used. In this paper, the validity of the proposed VBC system is verified by PSIM simulation package.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.54-60
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• 2006

Large steel industries have time-varying nonlinear loads such as electric arc furnaces. These nonlinear loads generate harmonic currents and create distortions on the sinusoidal voltage of the power system. The main objective of the static var compensator is to maintain the rms voltage at the point of common coupling within the limit. In this research, harmonic mitigation studies were conducted with and without the SVC, and time-varying harmonics were evaluated according to the international harmonic standards (IEC 61000-3-6 and IEEE Std. 519) using a cumulative probabilistic approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1407-1415
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• 2010

In recent years, the smart grid technique for maximizing the energy efficiency of power networks has received a great deal of attentions. In particular, the Demand Response is a core technology differentiated from the present power network under the smart grid paradigm. To minimize the electric cost and maximize users' satisfaction, this paper proposes a unique scheduling algorithm derived by using optimization where the characteristics of various home appliances are taken into account. For this goal, we represent mathematical consumption patterns of the electric loads and propose the optimal scheduling scheme based on the importance factor of each device during one day. In the simulation results, we demonstrate the effectiveness of the proposed algorithm in the viewpoint of the minimal electric costs utilizing real statistical figures.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2146-2156
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• 2017

When a failure occurs in active distribution system, it will be isolated through the action of circuit breakers and sectionalizing switches. As a result, the network might be divided into several connected components, in which distributed generations could supply power for customers. Aimed at decreasing customer interruption cost, this paper proposes a theoretically optimal island partition model for such connected components, and a simplified but more practical model is also derived. The model aims to calculate a dynamic island partition schedule during the failure recovery time period, instead of a static islanding status. Fluctuation and stochastic characteristics of the renewable distributed generations and loads are considered, and the interruption cost functions of the loads are fitted. To solve the optimization model, a heuristic search algorithm based on the hill climbing method is proposed. The effectiveness of the proposed model and algorithm is evaluated by comparing with an existing static island partitioning model and intelligent algorithms, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.573-580
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• 2014

The electrical reliability of the power generation and distribution system of Floating Liquefied Natural Gas vessels has been analyzed according to the operating modes using Electrical Transient Analysis Program in this paper. Electricity is used for the topside processes, cargo pumps for off-loading, thrusters for heading control and marine equipment. It is very important to improve the safety, efficiency, and stability of the electrical power system for successful operation. The voltage variation of the high and the low voltage bus shall be within the primitive limitation range at normal operation loads both in steady state and in the transient state. The power system was simulated and compared with class rule for design verification.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.186-192
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• 2011

Recently, due to the expansion of electric power demands, nonlinear load such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electric devices, disturbance of the electric power system and its influences on industries have been continuously increasing. In this research, we develop a novel aggregation algorithm by considering the harmonics characteristics for residential loads. Using data sets acquired from various experiments, we analyzed load characteristics according to harmonics and presented the results obtained the proposed method.