This paper discribes development of three-dimensional electric field computation system by surface charge method. Using this system, both potential and electric field in the case which includes resistance or true electric charge can be calculated. And this system is able to be connected to the pre/post processors, which is useful for us to make arbitrary shape and to display results of analysis.

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The DC electromagnets are widely used for the electromagnetic actuator of various electric apparatus, because its construction is simple and its poduction is easy. Until recently, the electromagnets were designed by empirical procedure using trial and error approach. Recently, with the use of Computer Aided Engineerng in industry, a new generation of poducts have been developed. It is necessary for the optimum design to obtain the dynamic behavior of the DC electromagnets.
In this paper, a new method which is solved by coupling the motion equation of the armature and the 3-D electromagnetic field analysis taking into account magnetic saturation and eddy current in the core is described. And then, the new method is applied to a clapper type DC electromagnet. The factors affecting the dynamic bhavior of the electromagnet, such as B-H curve and conductivity of the core, are investigated in detail.

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Combined Cycle Power plant takes advantage of the efficiency, fast startup, and small environmental impact. The operation design of this plant is required to make best use of this plant advantage, A large-scale non-linear mathematical model of this plant was developed to check the plant condition. This simulation model was combined with the optimization using Rosenbrock method. The operation design is optimized in two steps; _??_Step 1_??_: Some points of plant condition can be checked roughly._??_Step 2_??_: This plant operation is optimized to design using Rosenbrock method. This optimization is applied to design the combined cycle power plant operation. It is confirmed that this methods is effective for the design of plant operation. From this study, plant operation can be designed with this optimization to make best use of this plant advantage. Then operation design point is decided using the optimization method on some evaluation instead of heuristic method.

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This paper describes a technique on conductor bundle geometry optimization by the use of personal computer. To reduce the corona noise, in this paper, a new method for finding the optimal arrangement of subconductors with the minimum surface gradient is proposed. The charge simulation method is used to calculate the electric field of conductor surface and the nonlinear successive quadratic programming is applied to find the optimal arrangement of subconductors. Through some analytical comparisons and corona cage tests, it is proved that a new asymmetric conductor bundle proposed in this paper can more reduce the average surface gradient of the phase conductor and the corona noise than the asymmetric conductor bundle proposed by GE as well as the conventional symmetric ones.

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The electromagnetic quantities of the magnetic bodies and conductors are calculated by the Finite Element Method with Integral Equation and it is not necessary to divide the free air space. The field at an arbitrary point in the free air is obtained from the Integral Equation after the FEM-IEM analysis. In this paper, the magnetization is written in the terms of the unknown total scalar potential Ω, and the current vector potential T is added in the conductors. In order to calculate the unknowns defined in only the substances by FEM, it is necessary to establish the boundary condition by IEM. Then the calculation of the boundary condition on the surface of magnetic body requires high technical skills, so the formulation presented in this paper is improved by integration of parts. Results of the standard models specified by the IEE of Japan suggest the validity of our method.

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The electric field changes, the magnetic field changes, and UHF radiations were observed during the rocket-triggered lightning experiment using the 4 channels transient memory of its sampling frequency of 1 MHz. The sensors were a flat disk antenna, a loop antenna, and a disk corn antenna respectively. Concerning the initiation of the electric and magnetic field changes, a remarkable discrepancy between the rocket-triggered lightning to the tower and the one to the ground is noticed. That is, the former is initiated by a bipolar pulse of a large amplitude. On the other hand, the amplitude of the latter increases gradually. Preceding such kind of changes, UHF isolated pulses were also recorded. The statistics of the UHF isolated pulses are presented.

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Power distribution automation for future will have to be provided with many advanced functions and services for customers by an economical and high-performance communication system.
To meet this requirement, an optical fiber passive multidrop system is developed by theoretical and experimental study on cable cost, transmission capacity and performance.
In this paper, the most effective branch number is shown by estimating the fiber reduction merit and the optical transmission limit. In the case of 10⁴ customers, the economical configuration is that of two-step branches with 8 to 12 ports and the possible transmission rate is over 2 Mbps. Based on this arrangement, the multiplexed transmission method is designed and the demonstration system is constructed. According to the experiments, this system can cover the area of 5km distance.

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When the conventional simplified hunting discriminant having x_q, δ and so on is used, the hunting limits of the series capacitor transmission system and equivalent transmission system without a series capacitor are in agreement. But hunting is apter to occur in the series capacitor transmission system judged by detailed calculation of the inverse vector locus. This discriminant is obtained by assumption of no quadrature damper winding. But it has great hunting preventive effects. So, exact hunting discrimination results cannot be obtained in the case of assumption of no quadrature damper winding. As stated above, the conventional simplified hunting discriminant has weak points.
Hunting discrimination should be made at the frequency where the inverse vector locus passes through an imaginary axis. But it has become clear that hunting discrimination can be made roughly accurately by the damping torque coefficient of 0Hz. Based on this fact, the authors have introduced a new simple hunting discriminant for the series capacitor transmission system. The direct and quadrature damper windings have been considered in this discriminant. Naturally this discriminant sometimes gives different results to the series capacitor transmission system and equivalent transmission system without a series capacitor.

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This paper proposes a simulation-based learning environment called hypersimulator, as a thinking tool to enhance operators' understanding of complex phenomena in power systems. The hypersimulator is literally a simulator fused with a concept of hypertext, a personal visual simulator with user interfaces viewing multiple aspects of the phenomena in power systems. In the field of power system engineering, training simulators are used for operators to get the so-called skill-based and rule-based expertise of the operation. However, the training simulators are not effective enough to provide knowledge-based expertise based on deep understanding of mechanism of complex phenomena. An aim of hypersimulator is help novice operator to get such expertise through examining the phenomena and developing effective mental models (internal models formed in persons' mind) of them. Our approach to design the system is a user-centered one based on cognitive science and analysis of characteristics of power system's phenomena and operators' ways of thinking.
In this paper, first, the characteristics of operators' ways of thinking are analyzed as the preliminary investigation to get a basic design concept. Secondly, the concept and the features of hypersimulator are discussed. Finally the effectiveness of the system is demonstrated using simulation of phenomena in power systems.

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The Turbine Generator On-line Monitoring and Diagnostic Expert System described in this paper improves power plant reliability and eases operator work load during Daily Start-up and Shutdown (DSS) operation.
The expert system has the following features: (1) diagram-based domain-specific knowledge representation models to describe the large volume of expertise (about 5, 000 rules) for knowledge acquisition and for reasoning explanation, (2) the diagnosis reasoning process is divided into two parts, real time diagnosis and detailed diagnosis, so that the approximated causes which require immediate corrective measures can be identified in real-time basis (1_??_2s), and the detailed causes, which are mostly used for maintenance planning, and therefore, do not need immediate corrective actions, can also be obtained (though much time, about 1 cause/minute, is required for detailed diagnosis).
This paper covers system configuration, knowledge representation, inference strategy and man-machine interface. We completed a prototype of this system and will carry out the field test in 1989.

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This paper shows the basic characteristics of a current limiting element for the power system using Y-type high-T_c superconductor. (1) YBa₂Cu₃O_x-type superconductor was produced, which size was 4.7×1.5×47mm. (2) Current I and voltage V were measured under the low temperature of 50_??_100K. (3) The flow resistance and the resistance of the element were defind and evaluated from the I-V characteristics obtained under the conditions of lower temperature than the critical value T_c, and larger current density than the critical value J_c. (4) The resistance value change due to temperature rise also evaluated under the larger current than the critical current. (5) A schematic calculation was tried for the practical use in some power system condition.

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This paper describes a new control method for a realization of compact controller which can track the maximum power point of a photovoltaic solar power system. In the solar power system the maximum power control is indispensable because the available dc power varies with solar insolation and temperature. This controller is required to be compact. For the development of the controller the high frequency operation is essential. However the v-i characteristics of the solar array at the frequency have hysteresis. In such frequency region the conventional maximum power tracking methods which are based on the condition that the v-i characteristics show no hysteresis phenomena can not be responsible for control of the power system. Therefore, it is necessary to develop the new control method to obtain maximum available power from the solar array at the frequency region also.
In this paper the authors proposed a modified method of Prof. Boehringer's maximum power tracking technique. The computer simulation of the power system controlled by the proposed method shows excellent performances.

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This paper presents the results of economic assessment for nuclear fusion power reactors. In the study, we perform conceptual designs of commercial fusion power reactors, and, based upon the designs, the cost of electricity of the reactors is evaluated. The evaluation, however, inevitably requires estimates of various uncertain performances of future fusion power reactors. Considering the uncertainties, we extensively execute many sensitivity analysis and mainly discuss what factor is influential to the economy. The study reveals that the beta value of plasma, neutron wall loading on the first wall, current density in toroidal coils, current-drive efficiency, and the capacity factor have strong impacts on the cost of electricity of fusion power reactors.

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This paper investigates the contamination of the surface of various insulators which were suspended in the air at a certain altitude and connected in series, and shows that the salt-proof dishes attached to pin-type insulators work effectively against contamination.
Exposure tests of insulators in Okinawa Island have been made since 1985.
The results is follows:
(1) The higher was the insulator placed, the heavier become the contamination.
(2) The amount of contamination on the downward surface of the suspended insulators at the lowest position was considerably smaller than that of the insulators at the other positions.
(3) The extent of contamination of the pin-type insulators with the salt-proof dishes was far less in comparison to that of pin-type insulators without ones.
(4) The maximum equivalent salt deposit density was closely related to the small amount of precipitation during the observation period and the occurrence of high wind speed which was higher than 10 m/s.

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