• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.643-645
• /
• 1996

In order to improve the voltage profile of the system we introduce the reactive power devices. However, it is difficult to know which bus will be the most effective bus when we inject the reactive power supplier in it. This paper systematically determines indices of the system in order to locate reactive power devices in a power system. To prove the validity and effectiveness of the system we apply the proposed method to the 9 bus system.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.714-716
• /
• 1996

This paper presents an optimization method for optimal reactive power dispatch which minimizes real power loss and improves voltage profile of power systems using evolutionary computation such as genetic algorithms(GAs), evolutionary programming(EP). and evolution strategy(ES). Many conventional methods to this problem have been proposed in the past, but most these approaches have the common defect of being caught to a local minimum solution. Recently, global search methods such as GAs, EP, and ES are introduced. The proposed methods were applied to the IEEE 30-bus system. Each simulation result, compared with that obtained by using a conventional gradient-based optimization method, Sequential Quadratic Programming (SQP), shows the possibility of applications of evolutionary computation to large scale power systems.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.60-62
• /
• 2010

최근 태양광, 풍력 등의 분산전원이 배전계통에 도입되어 운영되고 있다. 현재의 배전계통에 스마트 그리드 연계 시 전력 공급의 신뢰성 및 안정성, 전력 품질의 확보를 위한 계통 계획이나 해석을 위해 가장기본적으로 역 조류를 고려한 전압강하 계산이 필요하다. 본 논문에서는 기존의 역 조류 전압강하 계산방법을 개선하여, 분산전원의 출력변동(역 조류)을 고려하여, 간편하게 전압강하를 계산할 수 있는 분산전원 대응형 전압강하 해석법을 제안하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.11
• /
• pp.2229-2235
• /
• 2009

In this paper, each specimen blended at weight proportions of 80% HDPE to 20% EVA, 70% HDPE to 30% EVA, 60% HDPE to 40% EVA, and 50% HDPE to 50% EVA was manufactured respectively. The insulation performances of the proposed insulator were compared with conventional XLPE, main insulating material of CV cable on the basis of the investigation results of DC insulation performances. From the space charge density, electric field and potential profiles with raising DC voltage and time variation in HE82, distortion of electric field distribution was improved. As EVA mixed into the bulks acts as nucleation in crystallization process of HDPE, the size of spherulites became decreased and finally formed continuous network structure. Ultimately, it resulted from extinction of space charge in the interfacial region of spherulites.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.2
• /
• pp.152-156
• /
• 2007

This paper proposes a method for real-time control of both capacitors and ULTC in a distribution system to reduce the total power loss and to improve the voltage profile over the course of a day. The multi-stage consists of the off-line stage to determine dispatch schedule based on a load forecast and the on-line stage generates the time and control sequences at each sampling time. It is then determined whether one of the control actions in the control sequence is performed at the present sampling time. The proposed method is presented for a typical radial distribution system with a single ULTC and capacitors.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.892-893
• /
• 2007

Industrial interest in switched reluctance motor (SRM) drives has varied since 1850s. This has been primarily due to the emerging markets for variable speed drives in consumer and industrial products, such as home appliances, air conditioning, hand tools, fans, pump motor, etc. However, SRM has been plagued with the acoustic noise and vibration problem by input power of fixed section. Therefore, This paper offers operating characteristics by dynamic simulation through the generalization of inductance profile and estimation of inductance according to current. the control methode are applied from DSP(digital signal processor) with voltage reference and position detection.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.3-5
• /
• 2002

Breakdown characteristics of a punch-through diode with n+p+p-n+ structure are analyzed with two-dimensional device simulation. Effects of base doping concentration and profile on the breakdown are presented. An analytical expression of a maximum base doping level for the punch-through breakdown is derived. The diode with a linearly graded base doping shows superior leakage current and capacitance is satisfactory for applications for low-voltage circuits.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.135-137
• /
• 2005

In servo system demanding precision dynamic characteristics, application of the Permanent Magnet Linear Synchronous Machines (PMLSM) has advantage of analysis convenience by simple geometry and thrust ripple reduction from the sinusoidal back electromotive force and excited stator. Therefore, this paper presents design of surface-mounted PMLSM with slotless iron cored stator according to coil turns to satisfy the rate thrust. Also, from dynamic analysis for servo application of manufactured motor with heavy mass, we offer accurate range of the DC link voltage and acceleration in rate speed. This is applied to speed reference profile considering system characteristics in total length of moving position.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1398-1400
• /
• 2005

In this paper, a modular dc-to-dc converter, in order to apply to the control board of train vehicles, is presented. Forward converter with active-clamp reset circuit and synchronous rectifier(SR) is employed to achieve high efficiency. To reduce the size and height of the converter, low profile magnetic components are used. The design and performance of the modular dc-to-dc converter with experiments on a 50W(5V/10A) prototype for the 60V$\sim$140V input voltage range are presented.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.273-275
• /
• 1998

This paper presents a method of determining the minimum amount of reactive power capacity installation and minimizing transmission line losses. It deals with maintaining voltage profile within an acceptable range with respect to the increase in load demand. Our approach provides three-different stages to power system planner. First stage considers existing capacitors. Second stage considers expanding the size of the installed capacitors. Third stage considers existing capacitors and newly installed capacitors whose locations are irrelevant to the locations of existing ones. Validity and effectiveness of the proposed algorithm are confirmed by results on modified New England 30 bus test system.