• Journal of Ocean Engineering and Technology
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• v.32 no.4
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• pp.279-286
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• 2018

The use of eco-friendly energy in the offshore plant system is expanding because conventional generators are operated by fossil fuel or natural gas. Eco-friendly energy, which replaces existing power generation methods, should be capable of generating the power for lighting protection equipment, airborne fault indication, parameter measurement, and others. Most of the eco-friendly energy used in offshore plant facilities is solar and wind power. In the case of using photovoltaic power, because the structure must be constructed based as flat solar panels, it can be damaged easily by the wind. Therefore, there is a need for a new generation system composed of a spherical structure that does not require a separate structure and is less influenced by the wind. Considering these characteristics, in this study we designed, fabricated, and tested a unit that could provide the most efficient spherical photovoltaic power generation considering wind direction and wind pressure. Our test results indicated that the proposed system reduced costs because it did not require any separate structure, used eco-friendly energy, reduced carbon dioxide emissions, and expanded the proportion of eco-friendly energy use by offshore plant facilities.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.131-138
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• 2007

In this paper, a novel nonlinear control method of the CVCF(constant voltage and constant frequency) output voltage for the three-phase PWM inverter with LC output filters is proposed. A nonlinear modeling including the output LC filters is linearized by feedback linearization theory, the controllers of which can be designed based on a linear control theory. It is applied to the DC/AC power conversion of the PWM inverter for stand-alone wind power generation system. It has been verified by the experimental results that the proposed control scheme gives high dynamic responses at load variation as well as a zero steady-state error.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.109-112
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• 2004

Photovoltaic energy and wind energy are very in constant depending on the season, time and extremely intermittent energy sources. Because of these reasons, in view of the reliability the solar and the wind generation system have many problems(energy conversion, energy storage, load control etc.) comparing with a conventional power plant. So, in order to solve these existing problems, hybrid generation system of photovoltaic(500W) and wind power(400W), which combines wind power energy and solar energy to have effect of supporting each other, was suggested. But hybrid generation system cannot always generate stable output with weather condition, the auxiliary power compensation apparatus that uses elastic energy of spiral spring to hybrid generation system was also added for the present study. And it may confirm that power was continuously provided to load by storing energy obtained from generating rotary energy of spiral spring generates in small scale generator.

• Journal of Power Electronics
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• v.10 no.6
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• pp.686-693
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• 2010

In this paper, a fault diagnosis method based on fuzzy logic for the three-parallel power converter in a wind turbine system is presented. The method can not only detect both open and short faults but can also identify faulty switching devices without additional voltage sensors or an analysis modeling of the system. The location of a faulty switch can be indicated by six-patterns of a stator current vector and the fault switching device detection is achieved by analyzing the current vector. A fault tolerant algorithm is also presented to maintain proper performance under faulty conditions. The reliability of the proposed fault detection technique has been proven by simulations and experiments with a 10kW simulator.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.1
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• pp.97-104
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• 2015

An electric-motor which uses electric energy to dry laundry in a dryer generates wind by rotating a fan. The roles of electric motor and fan are crucial for drying. To reduce the noises or vibration, their performances should be improved. However, it requires a relatively high cost to redesign them. In this case, redesigning the fan case rather than the motor or the fan would be easier and cheaper. This paper is to apply Taguchi dynamic characteristic concept with the ideal function of energy conversion to redesign the fan case. Not only the increase of the wind power but also the decrease of noise, vibration and the other side effects are resulted.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1463-1468
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• 2007

This paper presents the possibility of the electric energy harvesting using piezoelectric actuator which is operated by geared motor. The geared motor consisting of oval shape cam and speed controller was operated in the range of 40${\sim}$172rpm. The PZT actuator of $36L{\times}13W{\times}0.6H$ was used for energy harvesting and the results of the theoretical model were verified by comparing it with the measured response of a experimental setup. Experimental study for obtaining the optimal operating conditions, such as displacement variation of the PZT actuator and motor speed variation, was achieved. A power of 0.02mW at the geared motor speed of 172rpm and the PZT actuator maximum displacement of $500{\mu}m$ was measured. In this study, it was confirmed that the wind power can be used for MEMS based sensor operating and windmill health monitoring one.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.96-101
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• 2014

Wind power is the fastest growing renewable energy source in the world and it is expected to remain so for some times. Recently, there is a constant need for the reduction of Operational and Maintenance(O&M) costs of Wind Energy Conversion Systems(WECS). The most efficient way of reducing O&M cost would be to utilize CMS(Condition Monitoring System) of WECS. CMS allows for early detection of the deterioration of the wind generator's health, facilitating a proactive action, minimizing downtime, and finally maximizing productivity. There are two types of faults such as mass unbalance and aerodynamic asymmetry which are related to wind turbine's rotor faults. Generally, these faults tend to generate various vibrations. Therefore, in this work a simple fault detection algorithm based on spectrums of vibration signals and simple max-min decision logic is proposed. Furthermore, in order to verify its feasibility, several simulation studies are carried out by using GH-bladed software.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.1-9
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• 2003

This paper deals with the nodal admittance approach steady-state frequency domain analysis of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover as the wind turbine. The steady-state performance analysis of this power conditioner designed for the renewable energy is based on the principle of equating the input mechanical power of the three-phase SEIG to the output mechanical power of the variable speed prime mover mentioned above. Us-ing the approximate frequency domain based equivalent circuit of the three-phase SEIG. The main features of the present algorithm of the steady-state performance analysis of the three-phase SEIG treated here are that the variable speed prime mover characteristics are included in the approximate equivalent circuit of the three-phase SEIG under the condition of the speed changes of the prime mover without complex computations processes. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by variable speed prime movers such as the wind turbine(WT) employing the static VAR compensator(SVC) circuit composed of the thyristor phase controlled reactor(TCR) and the thyristor switched capacitor(TSC) controlled by the PI controller is designed and considered for wind-turbine driving power conditioner.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.38-40
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• 2009

In order to achieve a gearless construction of the wind energy conversion system(WECS), a low-speed generator should be used. Of the various candidate machine types, radial-field, multi-pole, permanent magnet, synchronous machines may be used for low-speed applications. So, this paper deals with the design of direct-coupled, multi-pole radial field machines with permanent magnet(PM) excitation for wind power applications for cogging torque reduction through the determination of optimum pole arc/pitch ratio. On the basis of an equivalent magnetic circuit method(EMCM) and a space harmonic method(SHM), an initial design is performed considering restricted conditions. And then, a detailed design is made using a non-linear finite element analyses(FEA). Finally, test results concerning generating characteristics are given to confirm the validation of the design.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.260-262
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• 2006

본 논문에서는 블레이드 피치각 변동을 포함한 풍력발전기 출력특성 시뮬레이션 모델을 개발하였으며, 피치각 변동이 필요한 경우를 각각 비상정지, 기동원활, 출력제한의 3가지 사례 연구를 통해 개발된 모델의 검증 수행하였다. 비상정지의 상황에서 풍력발전기의 출력특성을 모의하였고, 초기 정지 상태에서 블레이드 기동을 위한 초기 피치각 설정 및 변동하는 회전 속도에 맞는 블레이드 변동 지령 값을 구현하였으며, 정격 풍속이상에서 피치각을 감소시키는 제어기를 구현하여 정격이상의 출력 발생이 제한되는 것을 시뮬레이션을 통하여 확인하였다.