• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 A
• /
• pp.175-177
• /
• 2002

The use of underground transmission cables has increased continuously in densely inhabited urban and suburban for power transmission. Two or more transmission lines are outgoing from one substation in many cases, and one line comprises twin circuits. In order to meet the increasing do and for electric power, underground tables of two or fore circuits are installed in ducts in parallel for several kilometer in the same route. It, however, has not been known generally that the sheath circulating current is generated in a system where a large number of cables are laid on the same route. Therefore, this paper describes an improved analysis method for sheath circulating current on underground transmission cables using EMTP. Author propose several methods to reduce sheath circulating current. The analysing method and reduction methods for two or more underground cables will be really improved for cable system utility.

• 전기의세계
• /
• 제18권2호
• /
• pp.7-14
• /
• 1969

From the first customer located right at the substation to the last customer at the end of the line, voltage must be held within close limits, so the voltage regulation is more important than the thermal limit. On a typical distribution system during the peak load period, the voltage drop may be serious enough to cause unsatisfactory operation of home appliances in the residential area, and present many problems to manufacturing industries, where the voltage must be maintained within close limits to insure smooth operation. Among all the factors contributing to voltage drop in the distribution system, the voltage drop in the distribution transformer may account for 30% of this figure. If we can eliminate this factor, the power companies can provide better quality electricity to more customers with the existing distribution facilities, thus saving on initial investment costs. Taking all these problems into consideration, the author undertook the design of a capacitive transformer which would give zero voltage drop at rated load and at 80% lagging power factor while incorporating overload features to withstand 400% overload for at least 100 seconds. The following are the results obtained through design, manufacture and test of an initial experimental transformer built with these specific purposes.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 E
• /
• pp.1644-1646
• /
• 1998

High-Smokestacks have been the symbol of the thermal power plant. Those cause the thermal power plant to be damaged by lightening for reaching several hundreds meter. In this paper, we investigated the accident of low-voltage source circuit due to grounding potential rise by lightening via high-smokestack in practically driving power plant, described examination into the cause and the impulse analysis. We analysed the transient voltage by EMTP(ElectroMagnetic Transient Program) via modeling the grounding system of power plant. This theoretical results coincided with practical accidental state. Therefore, it was verified that we could apply the grounding system of power plant and substation with the distribution-circuit analysis(EMTP).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 B
• /
• pp.610-612
• /
• 1995

This paper presents the economic evaluation of battery energy storage system(BESS). Application target of the BESS was decided to both the distribution substation and single customer. 1MW/4MWh BESS under research and development in KERI was used for example. We analyzed and compared BESS with conventional combind cycle. The result shows that BESS is more economic than conventional combind cycle.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2000년도 춘계학술대회 논문집
• /
• pp.86-92
• /
• 2000

Recently, the Korea National Railways (KNR) is undertaking a program of electrification of the existing railway routes. In order to implement the ongoing plan, KNR authorized a preliminary engineering study of its electrical systems. This effort included a comprehensive analysis of new grounding networks. The new grounding system runs in parallel with the rails and is connected to all metal structures such as rails, overhead protection wires and substation grounding grids etc., creating an equipotential ground network. This paper presents a study on coupling levels that can disturb signaling and telecommunications in adoption of the new grounding network The simulation for the study is carried out using Matlab software, Several different scenarios are analyzed, including the load condition and a few fault conditions with different fault locations. The induced potentials on the communication cables are computed. The effect of the buried ground wires is also analyzed by comparing the results with and without the presence of the ground wires, The results presented in the paper can be used as a reference for estimating coupling levels in similar rail systems.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.648-649
• /
• 2007

변전소의 설비 관리/진단 및 보호, 감시, 제어 등의 자동화 시스템인 SAS(Substation Automation System)의 운영에 있어서 가장 중요한 요인은 System의 신뢰성 확보라 할 수 있다. 즉, Real-time Data에 대한 정확하고 빠른 취득능력은 SAS의 평가 잣대가 될 수 있다. 따라서 SAS 운영의 신뢰성을 증대시키기 위해 상위 HMI(Human Machine Interface)와 하위 Device간의 통신 중계 역할을 하는 I/O Server의 Virtual Simulation Environment인 Hyosung 통합 I/O Server Toolkit(Virtual Device 포함)을 개발하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
• /
• pp.1041-1043
• /
• 2005

It is expected to reduce stresses to components of high voltage circuit breaker and transferred switching surge from power system by applying controlled switching technique to high voltage system. This technique has already been applied to switch shunt reactor or capacitor bank in advanced countries. In this paper, operating software is installed in developed controlled switching device and HMI(Human-machine Interface) is under developing, In the future, this technique is expected to contribute to S.A(Substation Automation).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1161_1162
• /
• 2009

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and $CO_2$ emissions shall be addressed as important issue in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. For such new energy saving, the energy storage system is considered for saving energy. Energy saving is possible by efficient use of regenerated energy. Regenerated energy is recycled amongst vehicles by mean of charge and discharge corresponding to powering and braking of electric vehicle operations. This energy saving contributes to cut $CO_2$ to reduce greenhouse gas emissions. Recycling regenerated energy demonstrate significant effect on peak cut of consumption energy in railway substation. Absorption of excess energy avoids regeneration failure due to high traction voltage. Therefore, the energy storage system is needed to be adopted to use regeneration energy when the vehicle is braking.

• 조명전기설비학회논문지
• /
• 제21권1호
• /
• pp.42-51
• /
• 2007

AC 전기철도 시스템은 동적 단상부하가 빠르게 변화하고, 전철 급전변전소에서 3상 전력을 단상 전력으로 변환한다. 이것은 일반 배전 시스템과 비교해서 AC 전기철도 시스템의 전기적인 현상들이 다르다는 것을 나타낸다. AC 전기철도 열차부하의 전기적인 특성은 동적부하의 운영과 운행 스케줄, 트랙의 구배 등에 따라 연속적인 변화를 받고 있다. 이와 같은 열차부하의 운영에 따른 급전거리가 길어 전압강하, 전압 불평형 및 고조파 왜곡현상 등의 전력 품질 저하요인이 발생하게 된다. 이러한 문제점은 상위계통인 송전시스템의 안정도에 악영향을 줄뿐만 아니라, 전기철도 급전시스템의 전력품질 저하, 전기철도차량의 통신장비, 운행 및 수송량 제한에도 영향을 미치게 된다. 따라서 본 논문에서는 전기철도시스템의 과도상태 평가를 위해 PSCAD/EMTDC를 이용한 평가모델을 제시하고, 전압 강하에 주안점을 두어, 전기철도 급전시스템의 말단 분기점(Sectioning Post)에 정지형 무효전력 보상장치인 단상 배전 STATCOM(Single-phase Static Synchronous Compensator)을 설치하여 그 작용에 따른 전압강하 보상을 평가하였다.

• Journal of Electrical Engineering and Technology
• /
• 제13권2호
• /
• pp.540-549
• /
• 2018

This paper proposes the method of active distribution network expansion planning considering distributed generation integration and distribution network reconfiguration. The distribution network reconfiguration is taken as the expansion planning alternative with zero investment cost of the branches. During the process of the reconfiguration in expansion planning, all the branches are taken as the alternative branches. The objective is to minimize the total costs of the distribution network in the planning period. The expansion alternatives such as active management, new lines, new substations, substation expansion and Distributed Generation (DG) installation are considered. Distribution network reconfiguration is a complex mixed-integer nonlinear programming problem, with integration of DGs and active managements, the active distribution network expansion planning considering distribution network reconfiguration becomes much more complex. This paper converts the dual-level expansion model to Second-Order Cone Programming (SOCP) model, which can be solved with commercial solver GUROBI. The proposed model and method are tested on the modified IEEE 33-bus system and Portugal 54-bus system.