Motoo Futami

Output Power Smoothing and Hydrogen Production by Using Variable Speed Wind Generators

This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as an alternative energy source in the future, and this is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a serious influence on the power system operation. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.

Efficiency calculation of wind turbine generation system with doubly-fed induction generator

This paper presents a method to calculate various losses in wind turbine generation system (WTGS) as a function of wind speed, which is based on the steady state analysis. Variable speed WTGS using a doubly-fed induction generator (DFIG) and power converters (inverter and converter) is mainly considered in this paper. By using the proposed method, wind turbine power, generated power, generator losses, gearbox loss, power converter losses and energy efficiency can be calculated quickly. Moreover, annual energy production and capacity factor of the wind farm can be obtained by using the wind speed characteristic expressed by Weibull distribution function. Therefore, if the Weibull distribution function of wind speed is available, we can calculate the annual energy production without using real annual wind speed data. Using the data of Weibull distribution function of some different areas, capacity factor of each area is calculated and compared with those of other types of WTGSs such as Permanent Magnet Synchronous Generator (PMSG) and Squirrel-Cage Induction Generator (IG).

A Calculation Method of the Total Efficiency of Wind Generator

This paper presents a method to represent various losses in wind generator as a function of wind speed, which is based on the steady state analysis. By using the proposed method, wind turbine power, generated power, copper loss, iron loss, stray load loss, mechanical losses and energy efficiency can be calculated quickly. Calculation was done using a wind speed data expressed by Probability Density Function in order to predict capacity factor and total efficiency of a wind farm for one year. Finally it is concluded that the proposed prediction calculation method is effective, and can contribute to a wind generator design and construction planning of a wind farm.

A cooperative control method for output power smoothing and hydrogen production by using variable speed wind generator

This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as alternative energy sources in the future, and it is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a..serious influence on the power system. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.

A new wind generation system cooperatively controlled with hydrogen electrolyzer

This paper presents a cooperative control method of the wind generation system composed of multiple wind genera1tors and hydrogen generator. In this system, some part of the output power from the wind generators is consumed by hydrogen generator, and the other part, which is smoothed by the cooperative control between the wind generators and the hydrogen generator, is supplied to the grid. In this system, Doubly-Fed Induction Generator (DFIG) is adopted as a wind generator, which can be operated at adjustable speed. Each electrolyzer in the hydrogen generator is operated only at the rated power consumption mode (“ON condition”) or at zero power consumption mode (“OFF condition”), because fractional power operation can have a bad influence on the service life of electrolyzers. Therefore, since the hydrogen generator cannot smooth the fluctuating power from the wind generators completely, the smoothing control is performed by controlling the kinetic energy of DFSGs in this system. As a result, in the proposed system, smoothed power can be supplied to the grid system without using any energy storage device as well as hydrogen can be produced.

A Wind-Power Generation System Having a Function of Suppressing Line Voltage Deviation

Wind-power generation (WPG) tends to create voltage deviation in the distribution lines because wind speed always fluctuates. This paper proposes to add a new function to the interface converter of WPG, that is, generation of reactive power to suppress the voltage deviation caused by WPG itself. This paper also proposes a reactive power control strategy for the interface converter to suppress the voltage deviation. The validity is verified by simulation studies

Wind Farm Stabilization by Doubly-Fed Synchronous Wind Generator

Recently, an attention is being paid to the variable speed wind generator combined with power conversion device. Because this system can stabilize its output in spite of wind speed variations, it is effective in decreasing the fluctuation of the output from wind power plant. This paper proposes a new control method of a wind energy conversion system using Doubly-Fed Synchronous Generator (DFSG) to improve the stability of a wind farm in a large electric power system.

Continuous operation control during electric power network faults in an adjustable speed generation system with a flywheel excited by a DC link converter

For an adjustable speed generation system with a flywheel, not only quick active power and voltage responses, but also continuous operation during electric power network faults are necessary to stabilize electric power networks. Quick active power response of 40 rad/s and voltage response of 40 rad/s are obtained in a 30 kVA test model. To realize these quick responses, a controller with multi-microprocessors is used, in which the minimum sampling time is 185 /spl mu/s. Moreover, cooperative power flow control between the rectifier and inverter is added to power, voltage and speed controls of the generator/motor. Chopper control for overvoltage suppression is added to the DC link voltage control. Continuous operation can be realized even during such electric power network faults as 1-line, 2-line and 3-line ground faults due to these controls.

A digital automatic current control system based on an optimum assumed model

In this paper, a new ACR (automatic current regulator) scheme is introduced for brushless DC motors. It consists of a model closely resembling the motor and PWM inverter, an assumed rising pattern of the current, and a parameter estimation. Using the control scheme, the mean value of the motor current is kept at the reference current, and the transient current of the motor is kept equal to the rising pattern. For the disturbance, because of DC-line voltage change, the proportional path from the error to the duty cycle of the PWM signal stabilizes the ACR. This ACR scheme can be realized with a microcomputer. >