• 조명전기설비학회논문지
• /
• 제18권6호
• /
• pp.91-99
• /
• 2004

대부분의 저압 수용가는 단상 및 3상 부하를 동시에 공급할 수 있는 장점을 지닌 3상 4선식 배전시스템을 적용하고 있다. 이 시스템은 구조적인 간단함 때문에 종래의 단상 및 3상 부하를 분리하는 방식보다 편리하다. 그러나 고르지 못한 부하 불평형이나 낮은 전기품질은 출력저하나 손실과 같은 문제를 발생하고 있다. 본 논문에서는 실제현장에서 전압 및 전류 파형을 측정하여 국제적으로 허용되고 있는 전압불평형 기준과 비교 분석을 실시하였다.

• 조명전기설비학회논문지
• /
• 제24권5호
• /
• pp.145-151
• /
• 2010

전압 불평형은 수용가 설비에서 상당히 중요한 전기 품질의 하나로 간주되고 있다. 전압은 송전선로 계통에서는 평형에 가깝지만, 수용가에서의 전압 레벨은 시스템 임피던스의 불평형과 단상 부하의 고르지 못한 배분 등으로 인해 불평형이 될 수 있다. 콘덴서는 역률 보상으로도 사용되며, 비선형 부하에서 발생하는 고조파를 저감하기 위해 리액터와 함께 사용되고 있다. 전압 불평형이 존재할 경우 전류 불평형으로 콘덴서에서는 용량변화가 일어난다. 콘덴서와 리액터를 함께 사용하는 경우 사고 발생이 높은 편이다. 그래서 콘덴서 설비에 전압 불평형이 존재할 경우 전압, 전류 그리고 용량의 변화가 어떻게 진행되는지 확인하는 것이 매우 중요하다. 본 연구에서는 전압 불평형률이 존재할 경우 콘덴서 단독운전과 리액터의 부착시 전압, 전류 및 용량의 크기가 규정에서 제시한 범위 이내인지를 계산하였다.

• International Journal of Railway
• /
• 제3권2호
• /
• pp.60-67
• /
• 2010

This paper deals with an experimental study on the wheel flange climbing of railway vehicles, which is a major factor leading to derailment. An experiment is carried out on a 1/5-scale model wheelset of a truck used on a standard-gauge track, which is placed on a roller rig. The lateral external force acting on the wheelset is ramped up until derailment occurs under the condition of a fixed attack angle and wheel-load unbalance ratio. Three parameters, the height of wheel lift, the lateral force, and the wheel load acting on the outer rail, are measured until derailment occurs. From these measurements, it is possible to observe the behavior of the wheelset and to elucidate how the attack angle, the wheel-load unbalance ratio and the lateral external force affect flange-climb derailment. Then, a numerical simulation is carried out using an analytical model based on a single wheelset. As a result, the flange-climb behavior observed in the experiment can be explained theoretically on the bases of the analytical results, although further improvement of the model is desired.

• 전기학회논문지
• /
• 제66권11호
• /
• pp.1669-1674
• /
• 2017

In this study, We have discussed the development of a diagnostic device to detect and prevent electrical fire due to the arc caused by contact failure and partial disconnection at the connection part of the three-phase electric heater wiring used in the industrial field. The arc caused by contact failure and partial disconnection at the connection part of the electric heater shows a change in the current effective value. Therefore, it is possible to determine whether there exists a defect by analyzing the current unbalance factor and the number of current fluctuations with the diagnostic apparatus. The three-phase unbalanced heater is considered to be capable of determining defects through periodic measurement and trend analysis of the current unbalance factor. It is also expected that this device can be used not only for electric heaters but also for detection of defects in wiring and connections of electrical equipment having a characteristic of constant load current.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.1685-1688
• /
• 2004

I propose a modeling of a mechanism for weight fire uniformity measurement of a tire and a way I interpret a Sampling signal by Loadcell through an analysis, and to measure fire uniformity in this study. Correct a weight fire uniformity measurement was possible through the production of conversion and influence factor of a signal with a basis with the model who was an oscillation mechanics enemy.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
• /
• pp.106-108
• /
• 2005

3상 4선식 배전방식은 우리나라 저압 수용가에 널리 채용되고 있다. 단상과 3상을 혼합하여 사용하는 경우가 많아 전압불평형에 의한 여러 가지 문제를 발생하고 있다. 3상 4선식 배전시스템에서 3상 동력용으로 단독사용일 경우에는 별로 문제가 되지 않지만, 단상부하와 3상 부하를 혼용사용할 경우에는 부하의 불평형에 의한 어떤 문제를 발생하는지에 대해 저항성 및 유도성 부하를 대상으로 전압불평형율을 측정하고 분석하였다.

• 한국산업정보학회논문지
• /
• 제21권3호
• /
• pp.29-33
• /
• 2016

청정에너지 발전설비의 요구가 늘면서 태양광, 풍력, 연료 전지 등의 분산전원 개발이 급속도로 증가하고 있다. 반면에 이러한 증가로 인하여 배전시스템은 복잡해지고 있으며 무효전력으로 인한 역률 저감, 불평형 부하에 의한 불평형 전류 등의 문제점을 가지고 있다. 이러한 문제점들을 해결하기 위하여 본 논문에서는 태양광용 3상 4선 타입의 전력변환장치에 무효전력, 불평형 전류를 보상하는 알고리즘을 적용하였다. 제안한 태양광 전력변환장치는 기본 출력동작 뿐만 아니라 계통 전력 품질의 저해요소들에 대해서 보상이 가능하며 PSCAD/EMTDC를 이용한 시뮬레이션을 통하여 그 성능을 검증하였다.

• 전력전자학회논문지
• /
• 제25권3호
• /
• pp.213-218
• /
• 2020

In this study, we propose a control algorithm to reduce the unbalanced characteristics of a three-phase system power caused by the unbalanced load of the AC electric railway. Then, we verify its performance through the design of a power compensator and experiments applying it. Like electric railway systems, a Scott transformer is applied, and the load and single-phase back-to-back converters are connected to the M-phase and T-phase outputs. The back-to-back converter monitors the difference in active power between the unbalanced loads in real-time and compensates for the power by using bidirectional characteristics. The active power is performed through PI control in the synchronous coordinate system, and DC link overall voltage and voltage balancing control are controlled jointly by M-phase and T-phase converters to improve the responsiveness of the system. To verify the performance of the proposed power compensation device, an experiment was performed under the condition that M-phase 5 kW and T-phase 1 kW unbalanced load. As a result of the experiment, the unbalance rate of the three-phase current after the operation of the power compensator decreases by 58.66% from 65.04% to 6.38%, and the excellent performance of the power compensator proposed in this study is verified.

• 제어로봇시스템학회논문지
• /
• 제10권9호
• /
• pp.840-846
• /
• 2004

In this study, the performance of a heavy load pointing system has been investigated. The PI controller are being widely used in industrial application because of simple, cheap, and excellent performance. However, the requirement for control precision becomes higher and higher, as well as the plants becomes more and more complex. In order to achieve the satisfied control performance, we have to consider the affection of nonlinear factor contained in plant. In this paper, the neural-PI control law have been evaluated. The proposed controller is compared with the existing controllers through simulations, and the results show that the pointing accuracy of the proposed control system is improved against the disturbance induced by vehicle running on the bump course.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1212-1213
• /
• 2011

PWM(pulse width modulation) rectifier has unit power factor and low harmonic distortion with high power conversion efficiency in entire loading range. These merits of PWM rectifier help the spread of DC distribution system. In addition, if multiple PWM rectifiers can be operated in parallel connection, maintenance process can be simple and reliability of power source can be advanced because of the hot swapping is available. The other way, the load unbalance among rectifiers can force a converter to stop by over current. The surge current by closed circuit composition between rectifiers can force switching devices damage. In this paper, some problems that can occur in case of parallel operation of PWM rectifiers and problem eliminating methods are considered.