A sustainable production of electricity is essential for low carbon green growth in South Korea. Although wind energy is unlimited in potential, both intermittency and volatility should be tackled for smart grid integ...A sustainable production of electricity is essential for low carbon green growth in South Korea. Although wind energy is unlimited in potential, both intermittency and volatility should be tackled for smart grid integration in future. To cope with this, many works have been done for wind speed and power forecasting. It is shown that statistical techniques are useful for short-term forecasting of wind power. This paper presents a statistical wind speed forecasting. The wavelet decomposition is employed as a de-noising technique. An illustration will be given by real-world dataset. According to the result, the MAD (mean absolute deviation) is improved as much as 10%.展开更多
This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate hi...This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate high dv/dt and high frequency common mode voltages which are harmful for the drive applications. It reduces the motor bearings life and conducted EMI (electro magnetic interference) deteriorates the insulation. In this paper, a diode clamped multilevel (3-level) inverter is used to perform dual task. It generates HF (high frequency) current to be injected at the input of the three-phase front-end rectifier thereby improving the harmonic spectra and the power factor. It also drives the induction motor. The salient feature of this paper is that it does not require separate converters for improving power factor and to drive induction motor. Furthermore, inverter switches operate with ZVS (zero voltage switching), thus reducing the switching losses substantially, The voltage stress of the switches also has been reduced to half of the conventional 2-level converter. The inverter is operated with SPWM (sinusoidal pulse width modulation) technique. The simulation results for a prototype of 2.2 kW are presented.展开更多
In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we empl...In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma.It is found that the wavelength of 0.53 μm and the intensity of about 1020W/cm^2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances.展开更多
文摘A sustainable production of electricity is essential for low carbon green growth in South Korea. Although wind energy is unlimited in potential, both intermittency and volatility should be tackled for smart grid integration in future. To cope with this, many works have been done for wind speed and power forecasting. It is shown that statistical techniques are useful for short-term forecasting of wind power. This paper presents a statistical wind speed forecasting. The wavelet decomposition is employed as a de-noising technique. An illustration will be given by real-world dataset. According to the result, the MAD (mean absolute deviation) is improved as much as 10%.
文摘This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate high dv/dt and high frequency common mode voltages which are harmful for the drive applications. It reduces the motor bearings life and conducted EMI (electro magnetic interference) deteriorates the insulation. In this paper, a diode clamped multilevel (3-level) inverter is used to perform dual task. It generates HF (high frequency) current to be injected at the input of the three-phase front-end rectifier thereby improving the harmonic spectra and the power factor. It also drives the induction motor. The salient feature of this paper is that it does not require separate converters for improving power factor and to drive induction motor. Furthermore, inverter switches operate with ZVS (zero voltage switching), thus reducing the switching losses substantially, The voltage stress of the switches also has been reduced to half of the conventional 2-level converter. The inverter is operated with SPWM (sinusoidal pulse width modulation) technique. The simulation results for a prototype of 2.2 kW are presented.
基金Supported by the Research Council of University of Guilan
文摘In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma.It is found that the wavelength of 0.53 μm and the intensity of about 1020W/cm^2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances.