• 전기학회논문지P
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• 제67권1호
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• pp.15-20
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• 2018

This paper presents the method of ESS energy capacity calculation for stand-alone renewable energy generation system consisting of photovoltaic energy. There is almost no power from photovoltaic system during sunless days. So this source is very weak in terms of the power supply reliability. To improve problem of power supply, battery is mainly used Energy Storage System(ESS). The number of sunless days and Depth of Discharge(DOD) is important factor to determine energy capacity of battery. However, a many study for economical design is required due to the high cost of ESS. In this paper, we propose the new method of ESS energy capacity calculation by applying different DOD for operation with and without sun. We determine the Battery capacity using higher DOD of operation during sunless day than the DOD of the normal operation. And we carried out an economic analysis of the calculation results.

• 한국항행학회논문지
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• 제20권5호
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• pp.433-439
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• 2016

저가형 GNSS (global navigation satellite system) 수신 모듈에 DGNSS (differential GNSS) 서비스를 적용하기 위한 방안으로 거리 영역의 보정정보를 위치 영역으로 투영한 후, stand-alone으로 산출한 위치에 적용하는 DGNSS-CP 방식이 제안된 바 있다. DGNSS-CP 를 상용 수신기 또는 휴대폰에 적용하기 위해서는 항법 방정식의 관측행렬을 이용하여 위치영역 투영 방정식을 구성하므로, 각 위성의 시선벡터를 산출하여야 한다. GNSS 항법 메시지, 배치 정보 등이 시선벡터 산출을 위하여 사용되는데, 각 방법에 따라 정확도와 연산량 등의 성능에 차이가 발생한다. 본 연구에서는 제시된 두 가지 시선벡터 산출 방식에 따라 DGNSS-CP의 성능에 어떠한 영향을 끼치는지 확인하기 위하여, Septentrio PolaRx4 Pro 수신기에서 stand-alone mode 로 저장된 데이터에 해당 알고리즘을 적용하였고, 배치 정보를 사용하는 방법이 궤도정보를 사용하는 방법에 비해 정확도 면에서는 그 성능이 RMS (root mean square) 0.1 m 가량 저하되는 반면, 연산량은 약 1/15수준으로 줄일 수 있음을 확인하였다.

• 디지털산업정보학회논문지
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• 제12권2호
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• pp.1-6
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.16-23
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• 2012

This paper relates to a study on the economic of electrical storage device for supplying power in sunless days, in the stand alone PV/Wind hybrid system, which it is applied to separate houses. In a photovoltaic/wind hybrid power system used in a separate house, when only the battery is used in sunless days, the capacity of the battery is become larger. For example, as in recent days, if cloudy days are frequent due to anomaly climate, it is difficult to supply power stably by only the battery based upon pre-estimated sunless days. Accordingly, in order to supply stably power of new renewable energy such as solar to any separate houses, it is preferable to reduce the capacity of battery by decreasing the number of sunless days when estimating the capacity of battery and to drive the small generator for compensation of the power shortage.

• 전자공학회논문지CI
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• 제40권2호
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• pp.38-44
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• 2003

본 논문에서는 임베디드 리눅스를 이용한 Strong Arm CPU 기반의 독립형 영상처리모듈 개발에 대하여 기술한다. 독립형 영상처리모듈은 실시간으로 영상 데이터를 받아 thresholding, edge detection, image enhancement등의 영상처리 알고리듬을 수행하는 임베디드 장치이다. 개발된 독립형 영상처리모듈의 성능을 나타내기 위하여 비슷한 성능의 PC와 영상처리 알고리듬의 수행시간을 서로 비교한 결과 만족할 만한 결과를 얻었다. 본 논문은 임베디드 리눅스가 PDA들의 인터넷 장비에서뿐만 아니라, 산업용 장비에서도 응용될 수 있는 가능성을 제시하였다.

• Journal of Electrical Engineering and Technology
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• 제5권3호
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• pp.443-450
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• 2010

An enhanced control strategy for variable-speed unbalanced stand-alone doubly-fed induction generator-based wind energy conversion systems is proposed in this paper. The control scheme is applied to the rotor-side converter to eliminate stator voltage imbalance. The proposed current controller is developed based on the proportional-resonant regulator, which is implemented in the stator stationary reference frame. The resonant controller is tuned at the stator synchronous frequency to achieve zero steady-state errors in rotor currents without decomposing the positive and negative sequence components. The computational complexity of the proposed control algorithm is greatly simplified, and control performance is significantly improved. Finally, simulations and experimental results are presented to verify the feasibility and the robustness of the proposed control scheme.

• Journal of Power Electronics
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• 제19권4호
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• pp.1011-1019
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• 2019

In this paper, a buck-flyback (fly-buck) stand-alone photovoltaic (PV) system for charge balancing with a differential power processor (DPP) circuit is proposed. Conventional feed-back DPP converters draw differential feed-back power from the output of a string converter. Therefore, the power is always through the switches and diodes of the string converter. Because of the returning conduction path, there are always power losses due to the resistance of the switch and the forward voltage of the diode. Meanwhile, the proposed feed-back DPP converter draws power from the magnetically-coupled inductor in a string converter. This shortens the power path of the DPP converter, which reduces the power losses. In addition, the extra winding in the magnetically-coupled inductor works as a charge balancer for battery-stacked stand-alone PV systems. The proposed system, which uses a single magnetically-coupled inductor, can control each of the PV modules independently to track the maximum power point. Thus, it can overcome the power loss due to the power path. It can also achieve charge balancing for each of the battery modules. The proposed topology is analyzed and verified using 120W hardware experiments.

• 전기전자학회논문지
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• 제23권3호
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• pp.826-831
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• 2019

소형 독립형 태양광 전원장치는 조명장치, CCTV 등에 많이 활용되고 있다. 이러한 장치가 경쟁력을 가지기 위해서는 배터리와 같은 전력저장장치 수명이 매우 중요하다. 하이브리드 커패시터는 고밀도와 장수명의 장점을 가지고 있다. 본 논문에서는 하이브리드 커패시터를 이용한 독립형 태양광 전원장치를 제안한다. 전력변환장치의 구성하기 위해 하이브리드 커패시터의 충방전 특성 및 내부저항을 측정하였다. 일사량 변화에도 안정적인 최대 출력점 추종제어 알고리즘을 제시하였다. 제시한 시스템의 타당성을 검증하기 위해 18W의 하이브리드 커패시터와 10W태양광 전지를 이용하여 시제품을 제작하고 실험하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.258-259
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• 2012

This paper proposes a new control strategy to eliminate the harmonic components of stator current for stand-alone DFIG system feeding non-linear loads. In this method, the LSC operates as an active filter which is controlled by employing a proportional-integral and a resonant controller. And also, the stator current is used as the feedback signal for the compensator instead of the load current, so that the additional current sensor at the load side can be removed. The experiment is verified to validate the effectiveness of the proposed compensating method.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1123-1128
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• 2008

Marine facilities like buoy, lighthouse are operated with stand alone power supply system. This power system can consist of a stand-alone type power system such as PV(Photovoltaic) system, wave system or hybrid system which is not cooperated with a commercial power system. Generally, PV power system for marine facilities can not supply a sufficient power to buoy, because it is so influenced from weather condition. For solving this problem the hybrid power system with PV and wave is studied on a various area, that is why a hybrid power system is requires to overcome these problems. This paper will describe a generation characteristic of WEC(Wave Energy Converter) for buoy, and an AFS(Anti-Fouling System) influence on WEC.