Yukio Ishigaki

Instantaneous control method with a GTO converter for active and reactive powers in superconducting magnetic energy storage

A novel GPG (gate pulse generator) for gate-turn-off converters (GTOs) is presented that provides quick-response firing-angle control and pulse width-modulated (PWM) control. Using the GPG, instantaneous control of active and reactive powers for an SMES (superconducting magnetic energy storage) system using one GTO converter is studied.<<ETX>>

Instantaneous control method with a GTO converter for active and reactive powers in superconducting magnetic energy storage. [Gate Turn Off]

A new type of GPG (gate pulse generator) is presented to give GTO converters quick response firing angle control and PWM control functions. Using the GPG, an instantaneous control method of active and reactive powers for an SMES (superconducting magnetic energy storage) employing one GTO converter is studied.

Power control experiments using a 5 MJ superconducting magnetic energy storage system

A theoretical approach to the simultaneous control of active power and reactive power that is based on decoupling control theory is proposed. The idea has been applied to a 5 MJ superconducting magnetic energy storage system connected to a 6600 V power line. The control performance was confirmed by a simulator test, a dummy test, and a real machine test. This system used a dumping resistor for protection, but the stored energy in the magnet was successfully transferred back to the power line by the phase control operation of the thyristor converter in the dummy quenching test. Operation in the permanent-current mode was also verified, and the decay time of the permanent current was consistent with loss due to the forward voltage drop of the thyristor switch.<<ETX>>

Development of a 1 MJ SMES System with Use of a Superconducting Magnet Having Function of “Enthalpy Protection”

A 1MJ superconducting magnetic energy storage (SMES) system has been developed by a joint reserch of Tohoku Electric Power Co. Inc.,and Hitach Ltd.. A magnet applied to the SMES has a function of “Enthalpy Protection”. A new concept, that is, QI simultaneous control algorithm has been adopted to the main control system. The aspects mentioned above have verified through a system test carried out. Especially, the first test in the world concerning to the “Enthalpy Protection”has been successfully achieved.

A Scheme for Development of Superconducting Magnetic Energy Storage System with Function of “Enthalpy Protection”

A Superconducting Magnetic Energy Storage (SMES) has many possible applications in an electric utility power system, such as, power system stabilization, leveling of load fluctuation, substitution for pumped storage power plant etc.

Application of thyristor circuit breaker to ohmic heating coil power supply systems.

New ohmic heating coil power supply systems which can generate high voltage are studied to insure their effective and economical use in nuclear fusion devices. Several systems are conceived by using normal, module, and multi-stage repetition types of thyristor circuit breakers. The operation of these systems are analyzed by digital simulation. It is seen that these thyristor circuit breakers are practical and applicable in ohmic heating coil power supply systems.

DEVELOPMENT OF THYRISTOR PHASE CONTROL SYSTEM WITH COS−1 CHARACTERISTICS

This paper describes a new type of thyristor phase control equipment for the poloidal magnetic field coil power supply system of tokamak fusion device. A new, digital automatic pulse phase shifter (DAPPS) with an equidistant pulse control function and a fast response time is developed. A converter with cos −1 characteristics is provided in the thyristor phase control equipment to allow the thyristor rectifier control system to be linearized. Therefore, the thyristor rectifier of the poloidal magnetic field coil power supply system can be controlled quickly and the rectifier operated stably, in spite of sudden changes in the generator frequency from 50Hz to 100Hz. We believe that this new DAPPS will be a valuable addition to the inventory of control equipment for fusion devices.