Shoji Nishikata

A New Interconnecting Method for Wind Turbine/Generators in a Wind Farm and Basic Performances of the Integrated System

A new interconnecting method for a cluster of wind turbine/generators is proposed, and some examples of the basic characteristics of the integrated system are shown. This method can be achieved with a wind turbine generating system using a shaft generator system. A group of wind turbine/generators can be interconnected easily with the proposed method, and high reliability and electric output power with high quality are also expected. Moreover, since this method enables transmission of the generated power through a long-distance dc transmission line, the optimum site for wind turbines can be selected so as to acquire the maximum wind energy.

A new interconnecting method for wind turbine/generators in a wind farm and basic characteristics of the integrated system

A new interconnecting method for a cluster of wind turbine/generators is proposed, and some examples of the basic characteristics of the integrated system are shown. This method can be achieved with wind turbine generating system using a shaft generator system. A group of wind turbine-generators can be interconnected easily with the proposed method, and high reliability and electric output power with high quality are also expected. Moreover, since this method enables to send generated power through a long-distance DC transmission line, the optimum site for wind turbines can be selected so as to acquire the maximum wind energy.

Studies on a wind turbine generator system using a shaft generator system

In this paper a new de-link type wind turbine generator system using a shaft generator system, which is widely used for power sources in a ship, is proposed. The basic configuration of the proposed wind turbine generating system is first explained. And the equations expressing the system are derived. Then the steady-state characteristics of the generating system are discussed. We use an experimental system that can simulate the characteristics of a wind turbine in this study, because it is hard to operate an actual wind turbine in a laboratory. In addition, the transient responses of this system are investigated when the velocity of the wind is changed. It is shown that experimental results were very close to the simulated ones, supporting the usefulness of the theory

Tip speed ratio control of wind turbine generating system connected in series

Experimental and simulated investigations of tip speed ratio control for a wind turbine generating system consisting of series connected two wind turbine/generators and a current-source thyristor inverter are carried out. It is confirmed that tip speed ratios of the individual turbines can be controlled almost constant when wind velocities fluctuated, making an effective operation of the system possible.

Magnetic field and electromagnetic force analysis of 3-phase air-core superconducting power transformer

The superconducting windings of the air-core superconducting power transformer have possibilities of being exposed to a higher magnetic field than those of the iron-core transformer because of no special paths for magnetic flux. Thus, in this paper, the magnetic field and electromagnetic force acting on the windings of an experimental 3-phase air-core superconducting transformer are analyzed. From the results, it has become clear that the superconducting windings of the air-core transformer are exposed to a 3-dimensional magnetic field containing a rotational component.

Dynamic performance analysis of a wind turbine generating system with series connected wind generators and bypass diodes using a current source thyristor inverter

Dynamic performances of a wind turbine generating system consisting of series connected wind generators with parallel connected bypass diodes at rectified DC output terminals and a current source thyristor inverter are discussed. It is shown that the tip speed ratio of the individual turbine can be controlled almost constant with the proposed method, making an effective operation of the system possible.

Performance characteristics of a practical scale wind turbine generating system using a shaft generator system

In this paper, the performances of a new and practical scale wind turbine generating system are discussed. The system was constructed on the basis of a shaft generator system widely used in large ships. This system has many features such as high reliability and output power of high quality. It is shown that electric power with constant frequency and voltage with low distortion can be obtained with this novel system. Furthermore the analytical model for computer simulation is proposed. Good agreement between simulated and experimental results is obtained, confirming the validity of the model.

Dynamic control of series connected wind turbine generating system

Dynamic control for a wind turbine generating system consisting of series connected five wind generators and a current source thyristor inverter is discussed. It is shown that tip speed ratios of the individual turbine can be controlled almost constant at an optimum condition with the proposed method, making an effective operation of the system possible. Experimental investigations are also discussed for a system with two wind turbines to verify the usefulness of the proposed generating system.

Effects of System Parameters on the Performance Characteristics of a Wind Turbine Generating System Using a Current-Source Thyristor Inverter

The effects of various system parameters on the performance characteristics of a wind turbine generating system using a current-source thyristor inverter are investigated. The configuration of the system and a simulation model for predicting the dynamic performances of the system are first explained. Then, the effects of various parameters of the system, such as the short-circuit ratio of the synchronous compensator, on the steady-state characteristics and the dynamic performances of the system are discussed.

A proposal of improving the reliability of a wind farm using thyristor inverter connected in series with rectified outputs of the generators

A new topology for improving the reliability of a wind farm consisting of a set of wind turbine generators and a current-source thyristor inverter with series connected rectified outputs of the generators is proposed, and the basic characteristics of the whole system are explored from computer simulation and experimental results. In the proposed method, a diode is connected in parallel with each output of the rectifier for the turbine/generators to secure a continuing operation in the events of lack of output due to insufficient wind.