• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.832-837
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• 2015

The group method of data handling (GMDH) algorithm has proven to be a powerful and effective way to extract rules or polynomials from an electric load pattern. However, because it is nonstationary, the load pattern needs to be decomposed using a discrete wavelet transform. In addition, if a load pattern has a complicated curve pattern, GMDH should use a higher polynomial, which requires complex computing and consumes a lot of time. This paper suggests a method for short-term electric load forecasting that uses a wavelet transform and a GMDH algorithm. Case studies with the proposed algorithm were carried out for one-day-ahead forecasting of hourly electric loads using data during the years 2008-2011. To prove the effectiveness of our proposed approach, the results were evaluated and compared with those obtained by Holt-Winters method and artificial neural network. Our suggested method resulted in better performance than either comparison group.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.226-229
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• 2003

Increasing of the use nonlinear power electronics equipments, power conditioning systems have been researched and developed for many years to compensate the harmonic disturbances and the reactive power. The main function of power conditioning systems is to reduce harmonic distortions, since extensive surveys quantify the problems associated with electric networks having non-linear loads. The main function of power conditioner compensates the current instead of the voltage. Therefore the inverter used in power conditioner is mostly current controlled type. In this paper, the proposed current control algorithm is analysed and discussed about how to design the controller which can apply power conditioning operation for grid-connective PV power system. And also proposed control system. To verify the proposed current control algorithm, a comprehensive evaluation with theoretical analysis, simulation, experiment results is presented.

• Journal of Power Electronics
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• 제1권2호
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• pp.133-144
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• 2001

Power electronics plays an important role in providing an interface between fuel cells and loads. Furthermore, power electronic converters ensure that the power is reliably and efficiently delivered to the load in the required DC or AC form. In this paper, major types of fuel cells are presented. Basic structures, operating principles, and different applications of fuel cells are described. In addition, current status and future trends in the areas of power electronics for fuel cells are described. In addition, current statue and future trends in the areas of power electronics for fuel cell applications are explained. A review of fuel cell power electronic system topologies and basic requirements are given as well.

• Journal of Power Electronics
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• 제17권4호
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• pp.983-990
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• 2017

This paper proposes a model predictive control based on the discrete Lyapunov function to improve the performance of power electronic converters. The proposed control technique, based on the finite control set model predictive control (FCS-MPC), defines a cost function for the control law which is determined under the Lyapunov stability theorem with a control error compensation. The steady state and dynamic performance of the proposed control strategy has been tested under a single phase AC/DC voltage source rectifier (S-VSR). Experimental results demonstrate that the proposed control strategy not only offers global stability and good robustness but also leads to a high quality sinusoidal current with a reasonably low total harmonic distortion (THD) and a fast dynamic response under linear loads.

• 전자공학회논문지
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• 제50권2호
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• pp.80-87
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• 2013

본 논문에서는 VANET(Vehicle to vehicle Ad hoc Network)의 V2V 프로토콜을 위한 긴급 메시지 전송을 위한 거리 기반의 동적 CW 할당 기법을 제안한다. 제안된 방법은 트래픽 부하 문제를 해결하기 위해 거리 기반의 존 할당 기법을 통해 특정 존(Zone)을 나누고 동적으로 CW 값을 할당한다. 소스노드와 최외곽의 노드가 최소 CW 값을 할당받아 채널에 접속할 수 있는 확률을 향상시켜 선택적 긴급 메시지를 재방송을 통하여 중복 패킷들의 수를 줄였다. 이로 인해 대역폭의 효율적 사용이 가능하고 패킷 충돌확률의 감소로 긴급메시지를 신뢰성 있게 전송하는 방법을 제시했다. 또한 차량 밀도가 급격히 높아질 경우 전송 구간의 패킷 충돌 확률을 적용하여 CW 값에 적용함으로써 재 충돌 확률을 낮추는 방법을 제시했다. 제안된 방법의 효용성을 증명하기 위해서 고속도로 환경의 시나리오에서 거리 및 확률 기반의 동적 CW 할당 알고리즘을 적용하여 종단 간 지연, 네트워크 부하, 처리량이 향상됨을 보였다.

• Journal of Power Electronics
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• 제16권5호
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• pp.1869-1883
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• 2016

In recent years, some converter structures and analyzing methods for the voltage regulation of stand-alone self-excited induction generators (SEIGs) have been introduced. However, all of them are concerned with the three-phase voltage control of three-phase SEIGs or the single-phase voltage control of single-phase SEIGs for the operation of these machines under balanced load conditions. In this paper, each phase voltage is controlled separately through separated converters, which consist of a full-bridge diode rectifier and one-IGBT. For this purpose, the principle of the electronic load controllers supported by fuzzy logic is employed in the two-different proposed converter structures. While changing single phase consumer loads that are independent from each other, the output voltages of the generator are controlled independently by three-number of separated electronic load controllers (SELCs) in two different mode operations. The aim is to obtain a rated power from the SEIG via the switching of the dump loads to be the complement of consumer load variations. The transient and steady state behaviors of the whole system are investigated by simulation studies from the point of getting the design parameters, and experiments are carried out for validation of the results. The results illustrate that the proposed SELC system is capable of coping with independent consumer load variations to keep output voltage at a desired value for each phase. It is also available for unbalanced consumer load conditions. In addition, it is concluded that the proposed converter without a filter capacitor has less harmonics on the currents.

• Wind and Structures
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• 제31권3호
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• pp.241-253
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• 2020

The inerter-based vibration absorber (IVA) is an enhanced variation of Tuned Mass Damper (TMD). The parametric optimization of absorbers in the previous research mainly considered only two decision variables, namely frequency ratio and damping ratio, and aimed to minimize peak displacement and acceleration individually under the excitation of the across-wind load. This paper extends these efforts by minimizing two conflicting objectives simultaneously, i.e., the extreme displacement and acceleration at the top floor, under the constraint of the physical mass. Six decision variables are optimized by adopting a constrained multi-objective evolutionary algorithm (CMOEA), i.e., NSGA-II, under fluctuating across- and along-wind loads, respectively. After obtaining a set of optimal individuals, a decision-making approach is employed to select one solution which corresponds to a Tuned Mass Damper Inerter/Tuned Inerter Damper (TMDI/TID). The optimization procedure is applied to parametric optimization of TMDI/TID installed in a 340-meter-high building under wind loads. The case study indicates that the optimally-designed TID outperforms TMDI and TMD in terms of wind-induced vibration mitigation under different wind directions, and the better results are obtained by the CMOEA than those optimized by other formulae. The optimal TID is proven to be robust against variations in the mass and damping of the host structure, and mitigation effects on acceleration responses are observed to be better than displacement control under different wind directions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.521-524
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• 2005

To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2225_2226
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• 2009

An increasing of non-linear loads such as power electronic equipment in distribution systems is the reason for the greater concern about harmonics in recent time. A harmonic current and voltage in distribution systems can cause many problems such as malfunction of protective equipment. In this paper, Total Harmonic Distortion(THD) of voltage according to magnitudes and measurement locations of the non-linear loads was calculated and analyzed with Electro-Magnetic Transients Program(EMTP).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.566-569
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• 2004

The recent growth in the use of impactive and nonlinear loads, electronic devices sensitive to power quality has caused many power quality problems. Recently, in power system, not only the reliability of the power supply but also the DVR(Dynamic Voltage Restorer) are being studied more and more. The DVR is a series compensator which can instantaneously compensate a voltage variation in supply side, and is a more effective than a existing UPS(Uninterruptible Power Supply) which can be only used in limited range of loads such as single load. Hence, in this paper, a study of inverter side L-C filter output Voltage for DVR is discussed.