• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.102-108
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• 2015

This paper proposes a new fault isolation methodology for a smart protective device which plays an agent role on the smart grid distribution system with the distributed generation. It, by itself, determines accurately whether its protection zone is fault or not, identifies the fault zone and separates the fault zone through the exchange of fault information such as the current information and the voltage information with other protective devices using bi-directional communication capabilities on the smart grid distribution system. The heuristic rules are obtained from the structure and electrical characteristics determined according to the location of the fault and DG (Distributed Generation) when faults such as single-phase ground fault, phase-to-phase short fault and three-phase short fault occur on the smart grid distribution system with DG.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.159-162
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• 2002

A software, called touch-one, is developed about the determination of short-circuit values and protective co-ordination in power system. The used solution algorithm reviewed intensively, and the protective co-ordination determination technique presented by using the circuit-breaker's current-limitation characteristic. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. With this software, we can construct a electric-power system which is reliable and economic according to user's purpose.

• 전기학회논문지P
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• 제61권4호
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• pp.214-219
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• 2012

In this paper, the method of protective coordination is studied to install Superconducting Fault Current Limiter (SFCL) to power distribution system. If SFCL is installed, the protective coordination is not operated well because of the decreased fault current. Thus, the resetting method of protective devices is presented to coordinate protection system in power distribution system with resistor-type SFCL. The presented methods are divided into three parts; OCR, OCR-Recloser, OCR-Recloser-Recloser. The presented methods are proved through case studies using PSCAD/EMTDC simulation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 토목섬유기술위원회 학술세미나 논문집
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• pp.55-65
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• 2001

Geotextiles are usually constructed as a protective layer of geomembranes in liner systems for the solid waste landfill. A protective layer and geomembrane are susceptible to mechanical damage by coarse grains in the overlying drainage layer. In this study, therefore, the strain behavior of geotextile protective layers was investigated using three different types of devices for developing punctiform loads. The results of the study showed that the rates of strain was different depend upon device types for functiform loads. Also, It was found that the increases in strain was approximately linear in range 20 to 6$0^{\circ}C$ , and pp-filament non-woven geotextiles yielded a better efficiency than pp-staple fiber non-woven geotextiles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.525-526
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• 2007

Recently, there has been growing interest in utilizing distributed generation (DG). However, an insertion of DG to existing distribution system can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc,. The typical protection system of the existing distribution system is designed for radial network. But penetration of DG to distribution system changes existing unidirectional power flow to bidirectional power flow. Therefore, investigation to cover whole field of distribution system must be accomplished such as changing of protection devices rating by increasing fault current, reevaluation of protective coordination. This paper presents that PSCAD/EMTDC simulations was accomplished to analyze effect of DG on the distribution protective coordination. In addition, directional recloser-sectionalizer coordination are evaluates distribution system with DG by using PSCAD/EMTDC simulation.

• 대한전기학회논문지:전력기술부문A
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• 제49권6호
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• pp.280-288
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• 2000

Recently, there has been growing interest in utilizing cogeneration(COGN) systems with a high-energy efficiency due to the increasing energy consumption and the lacking of energy resource. But an insertion of COGN system to existing power distribution system can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc, because of reverse power of COGN, especially in protective coordination. A study on a proper coordination with existing one is being required. The existing power distribution system is operated with radial type by one source and protection system is composed based on unidirectional power source. But an Insertion of COGN system to power distribution system change existing unidirectional power source system to bidirectional power source. Therefore, investigation to cover whole field of power distribution system must be accomplished such as changing of protection devices rating by increasing fault current, reevaluation of protective coordination. In this paper, simulation using PSCAD/EMTDC was accomplished to analyze effect of COGIN on distribution fault current. Also, the existing protection system of 22.9[kV] power distribution system and customers protection system to protect of COGIN was analyzed and the study on protective coordination between of two protection system accomplished.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.241-243
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• 2002

Recently, great efforts are concentrated on the autonomous, adaptive protection schemes with advanced artificial intelligence and digital technology. It is highly required for a next generation protective system not only to detect and to clear a fault, but also to fit itself to the changing environment. In this paper it is suggested an evaluation method for the protection ability of a protective system in a distributed system. The suggested method is of bottom-up scheme, in other words, protection ability is estimated from the lowest level of parameters in each protective devices to the highest level of the whole protective system. This feature makes it possible to evaluate the protection ability either for the protective device(or a system), or for a protected system. And, in addition, it is enabled that the protectability concept can be applied in the design stage of a protective system for a distribution network. The proposed method is applied to a simple distributed network to show its effectiveness.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1727-1731
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• 2003

In this paper we proposed backward fuzzy Petri-net to diagnoses faults in power systems by using the time sequence information of protection system. As the complexity of power systems increases, especially in the case of multiple faults or incorrect operation of protective devices, fault diagnosis requires new and systematic methods to the reasoning process, which improves both its accuracy and its efficiency. The fuzzy Petri-net models of protection system are composed of the operating process of protective devices and the fault diagnosis process. Fault diagnosis model, which makes use of the nature of fuzzy Petri-net, is developed to overcome the drawbacks of methods that depend on operator knowledge. The proposed method can reduce processing time and increase accuracy when compared with the traditional methods. And also this method covers online processing of real-time data from SCADA (Supervisory Control and Data Acquisition)

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1810-1812
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• 1996

This paper deals with the surge protective devices to minimize damages of communication equipments in signal data lines. The basic circuit consists of zener diodes, spark gap and series impedances. Therefore the hybrid circuit using bipolar zener diodes as clamps and a three-electrode spark gap as crowbars was proposed. The surge suppression performances and the characteristics of frequency response were investigated experimentally. Consequently, it was found that the frequency bandwidth and surge suppression performances are excellent.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1876-1878
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• 1996

This paper describes the combination surge generator for applying performance tests of surge protective devices. The $8/20{\mu}s$ waveform applies to low impedance circuits and components and is commonly used to determine the characteristics of surge protective devices. And the $1.2/50{\mu}s$ waveform applies to high impedance circuits and components and is used for testing dielectric behavior. Therefore, the combination surge generator, which generates $1.2/50{\mu}s$ voltage waveform under open-circuit conditions and $8/20{\mu}s$ current waveform under short-circuit condition, was proposed. Also this generator can produce $10/1000{\mu}s$ as well as $0.5{\mu}s/100kHz$ ring waveform.