• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.147-153
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• 2010

When small scale wind and solar power generation systems are connected to conventional power distribution system. It is worried that it can affect the quality of electricity such as voltage variation, power factor, frequency, harmonics and flicker. Therefore, in this research, in order to investigate the effects of wind power generation equipments(AC link method) on electrical power quality, when they are connected to distribution system. Power quality analyzer was installed respectively at the front side of power conversion system of conventional wind generation system and secondary side of consumer's power supply at distribution line. Measurements on power quality were performed and the effects of the wind generation system on distribution system were analyzed when it was and was not operated. The results show that 0.34[%] increase on voltage variation, 0.145 increase on current crest factor and 0.6[$^{\circ}$] deviation on phase difference when the power generation system was operated.

• Journal of the Korean Solar Energy Society
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• v.24 no.3
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• pp.47-54
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• 2004

Photovoltaic energy and wind energy are highly dependent on the season, time and extremely intermittent energy sources. Because of these reasons, in view of the reliability the photovoltaic and the wind power generation system have many problems(energy conversion, energy storage, load control etc.) comparing with conventional power plant. In order to solve these existing problems, hybrid generation system composed of photovoltaic(500W) and wind power system(400W) was suggested. But, hybrid generation system cannot always generate stable output due to the varying weather condition. So, the auxiliary power compensation unit that uses elastic energy of spiral spring was added to hybrid generation system for the present study. It was partly confirmed that hybrid generation system was generated a stable outputs by spiral spring was continuously provided to load.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.59-63
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• 2005

The 800-kW PM (permanent magnet) synchronous generator is developed as a wind power generator. The matching converter is designed to control the torque and power depending on the wind speed regime. The generator starts to generate the power at the speed of 9 rpm and the rated output is generated at the speed of 25 rpm. The rated output power of an inverter is 750 kW when the PM synchronous generator is delivering 800 kW to the inverter. The inverter is specially designed to perform the maximum power point tracking (MPPT) at the low wind speed regime that is typical wind environment in Korea. The inverter test was done with a 2 MW M-G system at KERI (Korea Electric Research Institute). The M-G set has a 2 MW motor driver and a 38:1 gear to match the speed between the motor and the PM generator. The torque simulating the wind is applied to the PM generator by a DC motor. The test results show the inverter efficiency of $94.3\%$ at the rated power generating condition. The measured values show that the MPPT algorithm is working well. Overall reliability will be verified through the long-term site test.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.151-157
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• 2013

This paper proposes an online adaptive fuzzy controller for a wind energy conversion system (WECS) that is intrinsically highly nonlinear plant. In real application, to obtain exact system parameters such as power coefficient, many measuring instruments and off-line implementations are required, which is very difficult to perform. This shortcoming can be avoided by introducing fuzzy system in the controller design in this paper. The proposed adaptive fuzzy control scheme using self-structuring algorithm requires no system parameters to meet control objectives. Even the structure of the fuzzy system is automatically grows on-line, which distinguishes our proposed algorithm over the previously proposed fuzzy control schemes. Combining derivative estimator for wind velocity, the whole closed-loop system is shown to be stable in the sense of Lyapunov.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.182-190
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• 2011

This paper proposes a LVRT (Low Voltage Ride Through) control strategy which should be satisfied by grid-connected wind power system when grid faults occur. The LVRT regulation indicates rules or actions which have to be executed according to the voltage dip ratio and the fault duration. Especially the wind power system has to support the grid with specified reactive current to secure the grid stability when voltage reduction ratio is over 10%. The LVRT regulation in this paper is based on the German Grid Code and full-scale variable speed wind power conversion system is considered for LVRT control strategy. The proposed LVRT control strategy satisfies not only LVRT regulation but also makes power balance between wind turbine and power system through additional DC link voltage regulation algorithms. Because it is impossible to control grid side power when the 3-phase to ground fault occurs, the DC link voltage is controlled by a generator side inverter using the DC link voltage control strategy. Through the simulation and experiment result, the proposed LVRT control strategy is evaluated and its effectiveness is verified.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1587-1599
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• 2017

This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.852-857
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• 2010

As the wind has become one of the fastest growing renewable energy sources, the key issue of wind energy conversion systems is on how to efficiently operate the wind turbines in a wide range of wind speeds. In general, the wind speed is the main factor that impact on the dynamics of wind turbine system. Wind turbine algorithms are thus required to improve the performance of wind speed measurements. However, the accurate measurement of the effective wind speed using wind gauge and similar sensors is difficult such that control systems are needed for wind speed estimation using various techniques. Therefore, this research suggests the Maximum Power Point Tracking (MPPT) method for tracking the wind speed based on neural networks. Design experiments were carried out in laboratory environment to validate the application of the proposed method.

• Water Engineering Research
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• v.4 no.1
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• pp.1-17
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• 2003

A mathematical model was developed to simulate the performance of a prototype wind-powered reverse osmosis desalination system. The model consists of two sub-models operated in a series. The first sub-model is the wind-energy conversion sub-model, which has wind energy and feed water as its input and pressurized feed water as its output. The second sub-model is a reverse osmosis (RO) process sub-model, with pressurized feed water as its input and the flow and salinity of the product water or permeate as its output. Model coefficients were determined based on field experiments of a prototype wind powered RO desalination system of the University of Hawaii, from June to December 2001. The mathematical model developed by this study predicts the performance of wind-powered RO desalination systems under different design conditions. The system optimization is achieved using a linear programming approach. Based on the results of system optimization, a design guide is prepared, which can be used by both manufacturer and end-user of the wind-driven reverse osmosis system.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.230-237
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• 2013

This paper presents a novel nonlinear model of Switched Reluctance Generator (SRG) based on wind Energy Conversion system. Closed loop control with based Proportional Integrator current Chopping Control machine model is used. A Power converter in SRG can be controlled by using PI-CCC proposed model, and can be produced maximum power efficiency and minimize the ripple contents in the output of SRG. A second power converter namely PI based controlled PWM Inverter is used to interface the machine to the Grid. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltage needs less power switching devices and each pair of turbine the generated active power starts increasing smoothly. This proposed control scheme feasibility and validity are simulated on SIMULINK/SIM POWER SYSTEMS only.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.303-311
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• 2014

This paper shows the test result of 2MVA BESS(Battery Energy Storage System) with wind-turbine in micro-grid of the Gapado. To implement of micro-grid with BESS, characteristics of generator and customer load in grid are considered. Also, to operate of 2-parallel PCU(Power Conversion Unit) in BESS, the droop control is adopted with operating mode of grid independent. Performances of BESS with wind-turbine were verified by analysis of power quality such as voltage harmonics, ratio of voltage and frequency regulation, and by measurement of waveform such as output voltage and current.