Kokichi Ogawa

A field experiment on power line stabilization by a SMES system

Field experiments on stabilization of a hydro power plant by a SMES (superconducting magnetic energy storage) system are reported, where a generator having a rating of 60 kW at 3.3 kV is connected to a 6.6 kV power distribution line. The SMES system is composed of two 30 kVA GTO (gate turn off) converters and a superconducting magnet system with an energy of 30 kJ at 100 A. Experiments on stabilization for the generator fluctuation caused by a sudden insertion of inductors in the line were successfully performed for some control modes. The value of the SMES system to compensate for a short-period voltage dip is also confirmed. >

Experimental study of SMES system with DC intertie for power line stabilization

A superconducting magnet energy storage (SMES) system for power-transmission-line stabilization is studied using an experimental model system. It has a DC intertie section using convertors in an AC transmission line, with SMES used in series in the DC section. The distinctive characteristics of this system are that independent stabilization can be made for each AC line and that the power flow through the DC section can be controlled. The model system has pulsewidth-modulated GTO (gate-turn-off) converters, a superconducting pulse magnet, and a simulated power line system with generators. Measured characteristics of the system are discussed. Results of some simple line-fault experiments are shown.<<ETX>>

Study of SMES System with DC Intertie for Power Line Stabilization

A new superconducting magnet energy storage (SMES) system proposed by one of authors for power transmission line stabilization is studied by an experimental model system and computer simulation. It has a SMES in a dc intertie section connected to ac transmission lines via convertors. The distinctive characteristics of this system is that independent stabilization can be made for each ac line and also that the power flow through the dc section can be controlled. For verifying these characteristics we developed a model system consisted of a superconducting pulse magnet (lOOkJ), pulse width modulation (PWM) convertors, simulated power line system with a generator (lOkVA) and a short-circuiting device to give power line fault.

Relationship between magnetic poles and characteristics of revolving permanent-magnet type magnet wheels

The authors earlier proposed a revolving permanent-magnet type wheel called the “magnet wheel,” which has the functions of both induction repulsive magnetic levitation and thrust. In this paper, the relationship between magnetic poles and lift force or thrust characteristics is examined to investigate the performance. Five types of magnet wheels are discussed in an experimental study and four more types are used in a theoretical study with three-dimensional numerical analysis. The following parameters are considered: magnetomotive force (mmf) of a permanent magnet; thickness of the magnet in the magnetizing direction; total volume of magnets; fundamental factor; distortion factor of the space mmf distribution of poles; pole pitch; diameter of magnet wheel; mechanical clearance; and thickness and resistivity of conducting plate. The results show the following: 1. The lift force per unit of magnet volume is approximately proportional to the fundamental factor of the space mmf distribution of the poles. A low degree space harmonic mmf is effective in increasing lift force. 2. The driving power per unit of lift force is almost entirely independent of the configuration of the primary member, including pole arrangement and position relative to the secondary conducting plate, respectively, and depends only on the resistance of the conducting plate. 3. In both the “partial-overlap type” and “tilt type” magnet wheels, many poles with sufficiently large pole pitch are useful. In the tilt type the use of a small tilt angle is desirable.

Test Results of the SMES System in the Ariuragawa Hydropower Station

In light of high energy storage efficiency and very quick response in energy delivery, superconducting magnetic energy storage (SMES) systems are expected to find many opportunities of application for power system stabilization and for load leveling in place of pumping-up power plants. The authors have continued studies on SMES application to the power system since 1982 [l–3] and recently carried out a field tests, mainly relating to system stabilization, with a SMES connected to Ariuragawa hydropower station of Kyushu Electric Power Company. This paper describes some results of the test.

Finite element analysis of eddy currents problem subject to convective diffusion equation

The electromagnetic phenomena in the MHD devices, linear induction machines and the transportation of carriers in plasma and semiconductors are subjected to the convective diffusion equation. To solve the equation by numerical methods has recently become of a great importance. The paper presents the FEM analysis of linear induction machines assuming that the field quantities have reached the steady state.

Thrust of 2-pole PM linear synchronous motor with Halbach array

This paper describes the thrust and the airgap flux distribution of 2-pole PM linear synchronous motor, The feature of a Halbach array is discussed by comparing with two different type magnet arrangements. One is a conventional magnet arrangement. The other is composed of a Halbach array with a back yoke. 3-D boundary integral equation method is applied to these models. The thrust and the flux density are investigated changing design parameters of magnets.

Performance characteristics of 2-pole PMLSM with opposed type magnet arrangement of flux concentration

This paper describes the characteristics of the 2-pole linear synchronous motor with concentrated magnet arrangement, which consists of two-layer magnet arrays. The upper layer is a main pole composed of two normal excited magnets. The lower layer is composed of three tangentially excited magnets in which the same polarity faces each other. A 3-D boundary integral equation method is applied to the slotless core model, and its flux density distribution and the thrust are discussed and estimated. The effect of the slot opening is examined in a slotted model with the most effective magnet arrangement.

Thrust characteristics of 2-pole PMLSM composed of flux concentrated arrangement with Halbach array

Flux concentration in the airgap may attain by adding a Halbach magnet array on the surface of the main magnetic pole of a 2-pole permanent magnet linear synchronous motor (PMLSM) [1]. Thrust characteristics significantly change depending on the amount of flux concentration.