• Journal of Energy Engineering
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• v.12 no.4
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• pp.309-319
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• 2003

The main purpose of this paper is to present a simulation model for assessing the impacts of a variable speed wind turbine (VSWT) on the distribution network and perform a simulation analysis of volt-age profiles and harmonics along the wind turbine installed feeder using the presented model. The modeled wind energy conversion system consists of a fixed pitch wind turbine and a permanent-magnet synchronous generator, in which a controllable power electronics inverter performs variable speed operation and reactive power output control. Impact analysis on voltage profiles and harmonics of a VSWT-installed distribution feeder is addressed and simulated in terms of steady state and dynamic behaviors. Various capacities and different modes of variable speed wind turbines are simulated and investigated. Case studies demonstrate how feeder voltages are influenced by capacity and control modes of wind turbines and changes in wind speed under various network conditions, and show harmonic impacts on the feeder. Modeling and simulation analysis is based on PSCAD/EMTDC a software package.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.558-565
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• 2013

In this paper, modeling and simulation for performance analysis of high resolution SAR system has been carried out in the time, frequency and numeric domain using ADS Ptolemy simulation tool of Agilent corporation. SAR system consists of antenna, controller and transceiver. Error parameters affecting SAR system performances have been defined, modeled and simulated such as phase noise of frequency synthesizer, amplitude and phase characteristic of TWTA, sampling frequency of waveform generator and I/Q imbalance. Finally, the development requirements of SAR system based on the impulse response function have been derived.

• Journal of Power Electronics
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• v.14 no.2
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• pp.271-281
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• 2014

Fluctuating wind conditions necessitate the use of a variable speed wind turbine (VSWT) with a AC/DC/AC converter scheme in order to harvest the maximum power from the wind and to decouple the synchronous generator voltage and frequency from the grid voltage and frequency. In this paper, a combination of a three phase diode bridge rectifier (DBR) and a modified topology of the diode clamped multilevel inverter (DCMLI) has been considered as an AC/DC/AC converter. A control strategy has been proposed for the DCMLI to achieve the objective of grid interface of a wind power system together with local load compensation. A novel fixed frequency current control method is proposed for the DCMLI based on the level shifted multi carrier PWM for achieving the required control objectives with equal and uniform switching frequency operation for better control and thermal management with the modified DCMLI. The condition of the controller gain is derived to ensure the operation of the DCMLI at the fixed frequency of the carrier. The converter current injected into the distribution grid is controlled in accordance with the wind power availability. In addition, load compensation is performed as an added facility in order to free the source currents being fed from the grid of harmonic distortion, unbalance and a low power factor even though the load may be unbalanced, non-linear and of a poor power factor. The results are validated using PSCAD/EMTDC simulation studies.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.919-926
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• 2013

Experiments were conducted to determine the operating characteristics of a small-scale ORC (organic Rankine cycle) system for various low-temperature heat sources. A small-scale ORC power generation system adopting R-245fa as a working fluid was designed and manufactured. Hot water was used as the heat source, and the temperature was controlled using 110-kW electric resistance heaters that provided temperatures of up to $150^{\circ}C$. An open-drive oil-free scroll expander directly connected to a synchronous generator was installed in the ORC unit. Experiments were conducted by varying the rotational speed of the expander under the same heat source temperature conditions. The factors that influence the performance of the small-scale ORC system were analyzed and discussed.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.8-15
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• 2014

The objective of this paper is to suggest a design topology of permanent magnet synchronous generator with 2,000kW capacities for wind turbine. The suggested topology is to provide 3 split magnet PMSG instead of single magnet, and performed an analysis of eddy current loss and iron loss for suggested type using ansoft maxwell commercial program. The simulation results of suggested magnet type show there duction of eddy current loss as 13.87kW with loadless conditions and23.48kW with rated conditions, but iron loss for rotor yoke show the in creasing trend as2.2kW with loadless conditions and 0.2kW with rated conditions. The suggested 3 split maget type is to identified as more useful for 2,000kW PMSG.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.154-163
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• 2003

Grid connection essentially requires a wind energy conversion system (WECS) to not only supply adequate power responding to constantly varying wind speed but also provide a specified level of voltage magnitude and frequency that is acceptable in the electric power network. To satisfy such requirements, appropriate control schemes of a wind turbine to be connected to the power grid should be employed. This paper presents an output control strategy of a grid-connected wind power generation, which consists of a fixed-pitch wind turbine, a synchronous generator and a AC-DC-AC component with a voltage source inverter built in, and performs modelling and analysis of the strategy using PSCAD/EMTDC, an electromagnetic transient analysis software. Real power output control of the voltage source inverter is implemented to extract the maximum energy from wind speed inputted through wind blades and reactive power control, to keep the terminal voltage of WECS at a specific level. SPWM switching method is used to reduce the harmonics and maintain 60 ㎐ of the output frequency. The wind turbine performance and output corresponding to wind variation and the terminal load change is simulated and analysed.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1363-1369
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• 2015

The frequency of a power system should be maintained within the allowed limits for stable operation. When a disturbance such as generator tripping occurs in a power system, the frequency is recovered to the nominal value through the inertial, primary, and secondary responses of the operating synchronous generators (SGs). However, for a power system with high wind penetration, the system inertia will decrease significantly because wind generators (WGs) are operating decoupled from the power system. This paper proposes a dynamic droop-based inertial control for a WG. The proposed inertial control determines the dynamic droop depending on the rate of change of frequency (ROCOF). At the initial period of a disturbance, where the ROCOF is large, the droop is set to be small to release a large amount of the kinetic energy (KE) and thus the frequency nadir can be increased significantly. However, as times goes on, the ROCOF will decrease and thus the droop is set to be large to prevent over-deceleration of the rotor speed of a WG. The performance of the proposed inertial control was investigated in a model system, which includes a 200 MW wind power plant (WPP) and five SGs using an EMTP-RV simulator. The test results indicate that the proposed scheme improves the frequency nadir significantly by releasing a large amount of the KE during the initial period of a disturbance.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.381-385
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• 2009

Generally power system of ocean facility composes a solar generation system.The power to be generated by the solar system is changed according to the amount of sunlight of weather conditions. Output power of solar system is decreased with weather condition such as cloudy day and rainy day. And the power shortage of the ocean facility can occur due to the lack of solar energy. To solve this problem, this paper proposes the power control system for solar-wave hybrid system Wave generation system consists of wells turbine and permanent magnet synchronous generator(PMSG). This propose system set the specific area and measures the solar generation power and wave generation power. As a result of experiment, the solar power is a more static source than wave power, but the wave power provides energy during periods of no sunshine. The power characteristic of propose hybrid system have been obtained high reliability than a solar generation system.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.579-585
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• 2014

10kW wind turbine is widely studied in the field of renewable energy for the merits of easy installation to the confined area such as hill, park and urban areas. The performance of various electrical devices such as converter and inverter in the wind turbine system should be systematically analyzed for various wind speeds. However, it is impossible to apply these devices directly to practical wind turbine system for the safety of wind turbine system. Therefore, it is required to develop torque simulator which can generate corresponding torque according to its wind speed. In this work, 10kW torque simulator which consists of three phase torque control inverter, 3 phase induction motor and PMSG(Permanent Magnet Synchronous Generator) is developed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.357-360
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• 2013

A 1.8V 2-Gb/s scalable low voltage signaling (SLVS) transmitter (TX) is designed for mobile applications requiring high speed and low power consumption. It consists of 4-lane TX for data transmission, 1-lane TX for a source synchronous clocking, and a 8-phase clock generator. The proposed SLVS TX has the scaling voltage swing from 50 mV to 650 mV and supports a high speed (HS) mode and a low power (LP) mode. An output impedance calibration scheme for the SVLS TX is proposed to improve the signal integrity. The proposed SLVS TX is implemented by using a $0.18-{\mu}m$ 1-poly 6-metal CMOS with a 1.8V supply. The simulated data jitter of the implemented SLVS TX is about 8.04 ps at the data rate of 2-Gbps. The area and power consumption of the 1-lane of the proposed SLVS TX are $422{\times}474{\mu}m^2$ and 5.35 mW/Gb/s, respectively.