• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1172-1173
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• 2008

At the moment, the control ability of wind farms is a prime research concern for the grid integration of large wind farms, due to their required active role in the power system. As more wind turbines are installed, the power from wind energy will start to replace conventional generation units and its influence on power systems cannot be neglected. Besides, because of the intermittent nature of wind the output power of wind turbines fluctuates according to wind speed variation. Especially an isolated power system with small capacity such like Jeju needs more systematic solutions and regulations(grid code). This paper presents the idea of approach for centralized operating wind farm strategy to regulate the wind farm power production to the reference power ordered by the system operator. The doubly fed induction generator(DFIG) can control active and reactive power in feasible range. So wind farm comprised of DFIG has the possibility of a controllable component in the power system. The presented wind farm control has a hierarchical structure with both a wind farm control level and a wind turbine control level.

• 전기학회논문지
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• 제58권6호
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• pp.1123-1129
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• 2009

The main goal of this paper is to simulate a Doubly-Fed Induction Generator (DFIG), which is similar to a real system. Wind velocity data is applied to a 2D Lookup table as a speed reference for a turbine model. A real electric machine's parameters are put in the simulator to get some results of the real system. The Matlab have been generally used to simulate DFIG, but it has some differences from the real system and is difficult to implement. A Simplorer simulator, however, simplifies DFIG simulation. The turbine is directly connected with the DFIG to be close to the real system. The machine's rotor is excited and controlled by the discrete carrier modulated matrix converter. It is possible to retrieve important information, like a generated power and wind quality etc., from the simulator without a huge wind turbine.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.58-62
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• 2001

Photovoltaic and wind power generation have an advantage of unlimited and unpolluted amount of energy resource. In conventional wind generation systems, since the blade rotates at low speed when the velocity of wind decreases their operations are possible only under limited conditions. Therefore they are in trouble of self-generation without the help of auxiliary generation devices outside. The system driven by the wind force in this paper consists of a generator, an invertor, batteries and sets for power storage with a spring. In this paper, the operation characteristics of system were analyzed through experiments for a trial product.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1339-1342
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• 2005

This paper presents a simple AC-DC power conditioner for a squirell-cage induction generator(IG) operating under variable shaft speeds. The necessary reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM power converter size. A simple control compensating for changes in the electrical loads as well as the variation in speed was developed to regulate the voltages of the IG system by controlling the rotor flux through its reactive and active currents control implementation. This proposed power conditioning scheme can be used efficiently as a wind power generation system where the output voltage of the IG is maintained constant voltage despite the variable frequency and the DC bus voltage of the PWM converter can be used for either DC applications such as battery charging or AC power applications with 60/50 Hz by connecting a stand alone inverter. The experimental and simulated operating performance results of a 5 kW IG scheme at various speeds and leads are presented.

• 한국환경과학회지
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• 제18권8호
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• pp.919-926
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• 2009

Renewable energy or green energy is a hot issue in theses days. Since wind resource can be endlessly supplied by nature, researchers and common people are interested in study how to use that resource at home or company. Especially, many architects have tried to integrate wind power generator for a part of building. So in this paper, three buildings installed wind power turbine are targed to CFD analysis and these buildings are Bahrain trade center, Discovery tower, and Pearl river tower. Bahrain trade center is the first building installed real wind turbine, Discovery tower is constructing at Texas, and Pearl river tower is designed and proved by china researchers. These buildings have very different type of wind power turbine and each turbine has different conditions f3r best power generation. Therefor this paper will focus on characteristic shape of buildings, wind power turbine type, and expected purpose of construction. Moreover, CFD analysis will show wind flow pattern and wind speed while wind is passing through wind turbine of three tall buildings. CFD analysis for three buildings make comparison the wind flow patterns with experimental result.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.418-421
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• 2009

Renewable energy or green energy is a hot issue in theses days. Since wind resource can be endlessly supplied by nature, researchers and common people are interested in study how to use that resource at home or company. Especially, many architects have tried to integrate wind power generator for a part of building. So in this paper, three buildings installed wind power turbine are targed to CFD analysis and these buildings are Bahrain trade center, Discovery tower, and Pearl river tower. Bahrain trade center is the first builidng installed real wind turbine, Discovery tower is constructing at Texas, and Pearl river tower is designed and proved by china researchers. These buildings have very different type of wind power turbine and each turbine has different conditions for best power generation. Therefor this paper will focus on characteristic shape of buildings, wind power turbine type, and expected purpose of construction. Moreover, CFD analysis will show wind flow pattern and wind speed while wind is passing through wind turbine of three tall buildings. CFD analysis for three buildings make comparison the wind flow patterns with experimental result.

• Wind and Structures
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• 제18권6호
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• pp.599-618
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• 2014

In this study, a square rectangular tall building is considered to investigate the effects of turbulence integral length scale and turbulence intensity on the along-wind responses, across-wind responses and torsional responses of the tall building by Large Eddy Simulation (LES). A recently proposed inflow turbulence generator called the discretizing and synthesizing random flow generation (DSRFG) approach is applied to simulate turbulent flow fields. It has been proved that the approach is able to generate a fluctuating turbulent flow field satisfying any given spectrum, desired turbulence intensity and wind speed profiles. Five profiles of turbulence integral length scale and turbulence intensity are respectively generated for the inflow fields by the DSRFG approach for investigating the effects of turbulence integral length scale and turbulence intensity on the wind-induced responses of the tall building. The computational results indicate that turbulence integral length scale does not have significant effect on the along-wind (displacement, velocity and acceleration) responses, across-wind displacement and velocity responses, while the across-wind acceleration and torsional responses vary without a clear rule with the parameter. On the other hand, the along-wind, across-wind and torsional responses increase with the growth of turbulence intensity.

• 한국태양에너지학회 논문집
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• 제36권6호
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• pp.1-12
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• 2016

A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.258-264
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• 2018

본 논문은 마이크로 그리드 최적 운영을 위해 Differential Search (DS) 알고리즘을 적용하였다. DS 알고리즘은 이주하는 생물의 유사 브라운 운동 형태의 임의보행 (random-walk)을 모의하여 개발된 알고리즘이다. DS 알고리즘은 다른 최적화 알고리즘과 달리 한 개 이상의 개체를 동시에 사용 할 수 있고, 유사 최적해중에서 전역 최적 해를 선별하는 직진성 특성으로 multi-modal 함수들의 해법을 위한 성공적인 탐색 전력을 지니고 있으며, 높은 비선형성과 불연속성을 갖는 전력계통의 다른 분야에도 효율적으로 적용될 수 있다. 마이크로 그리드 시스템은 풍력 발전기, 디젤발전기, 연로전지 및 태양광 발전기로 구성된다. 풍력 발전기는 가변 출력특성을 이용하여 모델링 하였다. 연료비용과 연료가 전력으로 변환되는 경우의 효율을 포함시켜 시스템의 비용을 최소화 하였으며, 마이크로 그리드 단독 운용에 관해서만 분석하였다. 본 연구는 신재생 에너지원 기반의 마이크로 그리드의 최적 운영에 대해 코딩의 단순성, 빠른 수렴 속도, 정확성 및 효율성을 갖춘 DS 알고리즘을 적용하여 다른 알고리즘의 최적 값과 비교하였다.

• 전기학회논문지
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• 제62권7호
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• pp.918-924
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• 2013

In a conventional power system, the frequency is recovered to the nominal value by the inertial, primary, and secondary responses of the synchronous generators (SGs) after a large disturbance such as a generator tripping. For a power system with high wind penetration, the system inertia is significantly reduced due to the maximum power point tracking control based operation of the variable speed wind generators (WGs). This paper proposes a virtual inertial control for a wind power plant (WPP) based on the maximum rate of change of frequency to release more kinetic energy stored in the WGs. The performance of the proposed algorithm is investigated in a model system, which consists of a doubly fed induction generator-based WPP and SGs using an EMTP-RV simulator. The results indicate that the proposed algorithm can improve the frequency nadir after a generator tripping. In addition, the algorithm can lead the instant of a frequency rebound and help frequency recovery after the frequency rebound.