• 전기학회논문지
• /
• 제63권2호
• /
• pp.230-236
• /
• 2014

Superconducting fault current limiter (SFCL) has been expected as one of more effective solutions for decreasing fault current instantaneously and various types of SFCLs have been developed to apply into real power system. Recently, the application of the SFCL in a power distribution system has been reported to be contributed to the suppression of the voltage sag as well as the limitation of the fault current. However, the suppressing effect of voltage sag by the SFCL depends on component of its impedance and its application location in a power distribution system considering the recloser-recloser coordination. This paper analyzed the voltage sag caused by recloser-recloser coordination in a power distribution system and the suppression of the voltage sag due to the application location of the SFCL in a power distribution system was discussed through the PSCAD/EMTDC simulation.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
• /
• pp.353-357
• /
• 2004

This paper presents the result of survey of case study for harmonics in electrical installations of buildings. Recently, many power electronic equipments(power converter, computers, air conditioners electronic ballasts for fluorescent lamps and so on) are used in office buildings, and harmonic current from them influence the other equipments in a distribution line. Notably, voltage distortion or voltage harmonics may approach or exceed is allowable level in power distribution system. Individual electric power consumers and end-users and responsible for reducing current harmonics while companies or utilities are responsible for reducing voltage harmonics at the point of common coupling in distribution system. As for harmonics, which one of the electric power qualities, it becomes important to obtain harmonic voltage/current distribution of the power system precisely because the use of power electronic apparatus in increasing. To suppress harmonics in electrical ins tallations of buildings, one of many methods suggest that resonance frequencies are controlled by modulating the capacities of high-voltage customer's capacitors.

• Journal of Electrical Engineering and Technology
• /
• 제10권1호
• /
• pp.8-17
• /
• 2015

This paper analyses the power flow of a three-feeder/multi-bus distribution system by a custom Generalized Power Quality Conditioner (GUPQC). The GUPQC has been realized by three voltage source converters (VSCs) coupled back-to-back through a common DC-link capacitor on the DC-side. One feeder was controlled by the shunt compensator, whereas each of the other two feeders was controlled by the proposed novel series compensator. The GUPQC has the capability to simultaneously compensate voltage and current quality problems of a multi-bus/three-feeder distribution system. Besides that, the power can be transferred from one feeder to other feeders to compensate for poor power quality problems. Extensive simulation studies were carried out by using MATLAB/SIMULINK software to establish the ability of the GUPQC to improve power quality of the distribution systems under distorted supply voltage conditions.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 D
• /
• pp.2597-2599
• /
• 2004

The high quality power is consisted with uniform frequence, no interruption and uniform voltage. In these components, the voltage of the distribution systems affects making economic distribution facility and improving power quality. This paper describes on the voltage apportion rates of the distribution systems in KEPCO.

• Journal of Power Electronics
• /
• 제16권1호
• /
• pp.340-350
• /
• 2016

A cascaded hybrid multilevel inverter including a reconfiguration technique for low voltage dc distribution applications is proposed in this paper. A PWM generation fault detection and reconfiguration paradigm after an inverter cell fault are developed by using only a single-chip controller. The proposed PWM technique is also modified to reduce switching losses. In addition, the proposed topology can reduce the number of required power switches compared to the conventional cascaded multilevel inverter. The proposed technique is validated by using a 3-kVA prototype. The switching losses of the proposed multilevel inverter are also investigated. The experimental results show that the proposed hybrid inverter can improve system efficiency, reliability and cost effectiveness. The efficiency of proposed system is 97.45% under the tested conditions. The proposed hybrid inverter topology is a promising method for low voltage dc distribution and can be applied for the multiple loads which are required in a data center or telecommunication building.

• 전기학회논문지
• /
• 제67권6호
• /
• pp.702-707
• /
• 2018

In case of Lighting occurs in Domestic combined distribution line, normally the voltage for the neutral line increase dramatically. General connection for underground cable is bundled common earth type so the lightning over voltage increase at the concentric-neutral line is not big enough to give impact on cable sheath. But in case of Non bundled common earth type it is necessary to analyze the phenomena on cable sheath caused by lightening overvoltage. Especially pole and cable joint are the core factor to consider. In this paper concrete pole and cable joint were evaluated in case of Non bundled common earth type combined distribution Line. EMTP simulation model has been designed and several case study were made. Also several experimental test were made to verify the simulation result.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
• /
• pp.329-331
• /
• 1998

This paper presents a modified Learning Vector Quantization rule to control shunt capacitor banks and feeder voltage regulators in electric distribution systems with Kohonen Neural Network(KNN). The objective of the KNN is on-line decision of the optimal state of shunt capacitor banks and feeder voltage regulators which minimize $I^{2}R$ losses of the distribution system while maintaining all the bus voltages within the limits. The KNN is tested on a distribution system with 30 buses, 5 on-off switchable capacitor banks and a nine tap line voltage regulator.

• 조명전기설비학회논문지
• /
• 제16권5호
• /
• pp.38-44
• /
• 2002

본 논문에서는 배전선의 전압관리를 위한 계측시스템의 개발에 관하여 제안한다. 배전선 전압특성 및 측정상의 문제점이 분석되고, 전압관리를 위한 계측기의 기능에 대하여 제안한다. 노이즈 특성이 좋은 이중기울기(dual-slope) 방식의 A/D 컨버터를 적용하여 전압측정을 하는 알고리즘과 배전선 전압관리계기의 개발에 관하여 제안한다. IEEE 1159기준 분석에 따른 배전선의 정전 및 복귀 와 규정전압 초과 빈도 수 같은 전압변동 특성 등이 데이터베이스 제안에 의하여 분석된다. 실험을 통하여 그 편리성이 증명된다.

• Journal of Electrical Engineering and Technology
• /
• 제2권3호
• /
• pp.300-305
• /
• 2007

This paper reports an investigation of overvoltages caused by ferroresonance in the distribution system, which consists of a bank of open-delta single-phase voltage transformers. The high voltage sides of the voltage transformer are connected to the distribution system via three single-phase fuse cutouts. Due to the saturation characteristic of the transformer cores, ferroresonance can occur in the condition that the transformer is energized or deenergized with single-phase switching operation of the fuse cutouts. The simulation tool based on EMTP is used to investigate the overvoltages at the high side of voltage transformer. Bifurcation diagrams are used to present the ferroresonance behavior in ranges of different operating conditions. The simulation results are in good agreement with the results from the experiment of 22 kV voltage transformers. The mitigation technique with additional damping resistors in the secondary windings of the voltage transformers will be introduced. Brief discussion will be made on the physical phenomena related to the overvoltage and the damage of voltage transformer.

• 전력전자학회논문지
• /
• 제27권4호
• /
• pp.348-355
• /
• 2022

A bipolar DC distribution system suffers from an imbalance in voltages when asymmetric loads are connected at the outputs. Dedicated voltage balancers are required to address the imbalance in bipolar voltage levels. However, additional components eventually increase the cost and decrease the efficiency and power density of the system. Therefore, to deal with the imbalance in output voltages without adding any extra components, this study presents a coupled inductor-based voltage balancing technique with a dual-output CLL resonant converter. The proposed coupled inductor does not require extra magnetic components to balance the output voltages because it is the result of resonant inductors of the CLL tank circuit. It can also avoid complex control schemes applied to voltage balancing. Moreover, with the proposed coupled inductor, the CLL converter acquires good features including zero voltage and zero current switching. Detailed analysis of the proposed coupled inductor is presented with different load conditions. A 3.6-kW hardware prototype was built and tested to validate the performance of the proposed coupled inductor-based voltage balancing technique.