Oxide superconducting wires have been developed for application to electric power apparatuses in the Super-GM project. We have made steady progresses in the fundamental wire properties such as current capacity, wire length and critical current density (Jc). 125m long Bi2223 wire, 4.1 kA Bi2212 conductor, 1m long Y123 coated wire with Jc of 210 kA/cm² and 10m long T11223 wire with Jc of 20 kA/cm² were developed. Moreover we have developed the elemental technologies for wire application to apparatuses due to fabrication and evaluation of small pancake coils using Bi-based wires, 1kArms class Bi2212 AC lead and Y123 thin film type current limiting elements. Fabrication methods for long wire and large current conductor were established for Bi-based materials and basic technique for fabricating high Jc Y123 and T11223 coated wires were developed.

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Gas insulated transformers have been applied to the substations widely from the view points of the fire prevention and the land shortage. The cellulose fiber pressboards that have been used in the oil immersed transformer for the long term are also adopted as a main insulated material for lower voltage and smaller capacity gas insulated transformers so far. However, thermally upgraded and low permittivity dielectrics are desired to realize higher voltage, large capacity gas insulated transformer. Then authors focus on new synthetic fiber pressboard that made of mixture of polyethylene terephthalate (abbr. PET) and polyamid fibers. But there is no report investigated about the characteristics of the new synthetic fiber pressboard in the application to gas insulated transformers. In this paper, the authors report the investigated results of this material about mechanical, physical, dielectric characteristics of this material from the comparison with these characteristics of the conventional cellulose fiber pressboard. It is described that the application of this new synthetic fiber pressboard to world highest voltage and largest capacity gas insulated transformer.

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Generally, heavy leakage currents flow along the contaminated and wetted insulator surface. In case of weak power source, applied voltage is remarkably reduced due to such heavy leakage currents at the flashover/withstand voltage test of contaminated insulators. So, higher flashover/withstand voltages have been obtained on contaminated porcelain insulators by a weak power source. However, the influence of power source on flashover/withstand voltage of contaminated hydrophobic polymer insulators has not been clarified yet.
We investigated the influence of power source on contamination withstand voltage of polymer insulators by a stiff and a weak power source. As the results, in case of light contamination condition, any discernible effects of power source on contamination withstand voltage of hydrophobic polymer insulators couldn't be observed. On the other hand, in case of heavy contamination condition, significant effect was observed.

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Some physico-chemical analyses using Gas Chromatography/Mass Spectrometry, Thermogravimetric Analysis, and Differential Scanning Calorimetry, were performed for evaluation of surface degradation of silicone insulating materials. A comparison between virgin and aged silicone rubber samples, which were aged either on actual power lines or during field exposure test, was made. Lower shift in the molecular weight distribution of siloxane species and loss of siloxane matrix was observed as a result of depolymerization during outdoor aging. Since only miligram quantities of samples are required, these technique might be developed into a diagnostic tool for estimation of surface degradation and remaining life of the insulation.

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Network of Chugoku Electric Power co. is connected to the networks of other utilities and a fault occurred at the network may cause loss of synchronism between generators belonging to the west side of the network and the remaining generators. In order to prevent a wide area blackout, power system stabilizing controller (SSC) is implemented which checks many cases of stability studies, selects generators to be shed for stabilization and shed them when a fault takes place actually. This paper presents development and application of a new approach to construct external equivalents for power system stabilizing controller.

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A daily scheduling algorithm of Photovoltaic-Power Storage System (PV-PS) and an economic estimation for its allocation in a transmission open access environment are presented in this paper. In addition to the total profit of transmission system operation, an expected profit of PV-PS daily operation is estimated using a spot market pricing of short run marginal cost. A desirable allocation point of PV-PS is discussed from various view points of economy and available solar energy etc. To demonstrate the effectiveness of the proposed method, numerical examples for a model power system of 44 nodes, 8 thermal units and one PV-PS are shown in detail including daily profits of system operator, PV-PS producer and consumers through the PV-PS operation.

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This paper presents an outline of an operation simulation program, developed at Tokyo Electric Power Company (TEPCO), of power plants in large power systems, mainly utilized for generation mix planning. The simulation algorithm of the operational performance of pumped-storage hydro plants is focused on in this program.
One of the main goals in a generation mix planning problem is to minimize the total of investment and operation costs. Applying a mathematically optimizing method to solving a generation mix problem involving the complicated operation of pumped-storage hydro plants has so far proven difficult, and has been in little use at TEPCO for actual power source development planning. The developed program simulates practical operation of the pumped-storage plants in order accurately to evaluate the annual operation cost. In this simulation program, each pumped-storage plant is operated taking into consideration of the condition of its reservoirs as well as their weekly operation cycles.
An application result of this program to a study of the quantitative optimization of pumped-storage hydro in a model system with nuclear plants and thermal plants of various fuel-fired types is presented.

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We had studied a distance relay operation for a three-phase short circuit fault with unbalanced arcing phenomena in a three-phase gas-insulated circuit breaker. It revealed that the incorrect operation of mho-elements in reverse fault was due to the unbalanced fault resistance and the distorted voltage waveform. (see PSR-97-16) In this paper, we report the modeling test results of a distance relay using artificial transmission line and some consideration of a transverse differential relay operation for same phenomena.

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This paper deals with the dielectric characteristics of turn-to-turn insulation for SF₆ gas-insulated transformers for impulse voltages which are supposed to impinge on transformer in the field. Those are alternate application of impulse voltages with inverse polarities, superimposed application of impulse voltages on ac voltages and repetitive application of impulse voltages.
We obtained following results. The application of inverse polarity impulse and the superposition of impulse on ac voltage have no effect on dielectric strength of turn-to-turn insulation. And the repetitive application of impulse voltages over the partial discharge inception voltage level dose not promote degradation of turn-to-turn insulation.

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An impulse measuring system is recommended by IEC standard 60060-2, to be calibrated by connecting a reference measuring system in parallel and taking simultaneous reading on both systems. The testing voltage waves are usually chopped by a sphere gap.
In the calibration test, a noise induced through a coupling capacitance between the sphere gap and the voltage divider may have an effect on the measured wave.
This paper discusses the effect by using equivalent circuits and shows that the error in the time domain before the sparkover of the sphere gap can be estimated as about 1/4 of the noise measured without the connecting lead between the sphere gap and the voltage divider.

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In the DC system, the DC converter transformer is subjected to the polarity reversal voltage, which induces the transient field intensity in the oil portion of the oil-immersed insulation system.
In the paper, the transient field intensity is discussed during the DC polarity reversal in the oil-immersed insulation system. The authors describe a calculation method of the transient field intensity, using the surface charge method. The estimation method of the dielectric breakdown field intensity is proposed for the DC polarity reversal voltage. The estimated breakdown field intensity is compared with measured one.
Based on the calculation method of the transient field intensity, authors also investigate the effects of temperature and polarity reversal time on the transient field intensity during the polarity reversal.

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The lightning damage on low voltage distribution systems is almost burning of low voltage distribution equipment due to flashover and are dynamic current. The lightning overvoltage causes flashover of low voltage distribution equipment. After that, the flashover causes burning, because of the impression of the commercial frequency voltage. So far, the authors have clarified this lightning damage mechanism experimentally. According to these experiments, it was proved that which equipment in a low voltage distribution line suffered the lightning damage. And, it was also proved that restricting the lightning damage position in a low voltage distribution line was possible analytically by using the EMTP. In this paper, the method for calculating the lightning damage ratio of low voltage distribution equipment is described. To begin with, the relationship between lightning damage position in a low voltage distribution line and lightning stroke current value is calculated according to the current value divided small. Next, each lightning stroke current level is compared with cumulative frequency distribution of peak return-stroke currents, electricity geometric striking distance model, etc.. And finally, the lightning damage ratio is calculated. Using this method, the lightning damage ratio was calculated for several lightning protection in low voltage distribution system, and each effect was quantitatively verified.

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Phosphoric acid transfer phenomena along new or used porous carbon plates were investigated. Two adjacent 15cm sections of a 30cm porous carbon plate were filled with 105% phosphoric acid to different fill levels, kept at 180°C for between 2_??_85 hours and acid transfer from the acid-rich portion to the acid-poor portion was measured. Whereas a uniform decrease in the acid fill levels of the acid-rich portion was observed, unbalanced distributions of acid fill levels were observed in the acid-poor portion. The acid stopped to move within 24 hours despite the unbalanced distribution of acid fill levels in the acid-poor portion. As the initial fill levels of both portions decreased, the slope of the acid-poor portion fill level became steep. When the acid fill level in the acid-rich portion decreased below 30% in this used porous carbon, the acid showed no transfer. The slope of acid-poor portion fill level in new porous carbon plates was steeper than that of used porous carbon plates. These limitations on acid transfer can be explained by the difference between the forward and backward wetting angles on the acid/carbon materials boundary.

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There are plans of transmitting electricity by 1000 kV voltage to improve the efficiency of the utilization of the substations. The bushing that was developed for 1000 kV transmission lines, had a critical condition of the seismic performance, because it was taller than conventional types of voltage range under 500 kV to ensure the larger insulating performance. Therefore, it was confirmed that the bushing, fixed on the vibration table satisfied the seismic safety.
This paper presents results of experiment and analysis as to the vibration behavior of the bushing system, that is connected with connecting leads and is fixed on a concrete foundation, The vibration test was carried out by exciting the foundation. According to the test results, it was found that the connecting leads had a damper effect reducing the bushing response to nearly 20% in the resonance characteristic. It was shown that this damper effect was similar to that of a tuned mass damper. And further, the non-linear behavior of the connecting leads depending on the exciting force, the optimum parameters of connecting leads for damping, and the damper effect of the connecting leads exciting by 3m/s² three-cycles sinusoidal wave, were discussed.

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This paper proposes a contactless method to measure a surge voltage waveform on an overhead transmission line and on a cable sheath enclosed in a corrosion-proof layer. To measure surge voltage and current waveforms on the overhead line, the method is based on electro-magnetic coupling between the overhead line and a surge sensor, composed of a closed loop which is a distributed parameter line. The surge waveform is estimated from the induced voltage to the closed loop and from a Z-parameter theory. To measure a cable sheath voltage waveform, the method is based on electro-static coupling between the sheath and a detecting electrode, which is portable and detachable, and is composed of quite simple components and its potential dividing ratio is adjustable by a lumped capacitor. The proposed method is inexpensive and easy to measure surge waveforms with reasonable accuracy, and also is applicable to a surge measurement on a live line because of its contactless nature.

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Recently, to suppress the Nickel dissolution from the NiO cathode, Li/Na carbonate tends to be used as the electrolyte of molten carbonate fuel cells instead of Li/K carbonate. With Li/Na carbonate electrolyte, due to the higher ionic conductivity and the lower solubility of NiO, the decay rate of the stacks is expected to decrease. The single cell with Li/Na was operated over 12, 000 hours, resulting that the decay rate of the stack was presumed 3 mV/1000 hours. This value is less than that of the stack with Li/K carbonate, 4.5 mV/1000 hours. This presumption was agreed with that of the decay rate of the stack with Li/Na electrolyte operated over 6000 hours. Moreover, the effect of the electrolyte loss rate on the performance decay was deducted. The performance decay of 1.8 mV/1000 hours was expected for the stack equiped both with Li/Na carbonate and the advanced cathode current collector (slit firm type).

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In near future, it expects that PV systems will be interconnected to the utility distribution lines with high density. The PV systems are required to detect short circuit fault on the distribution line in order to prevent serious failure of the utility's protection device installed in the substation, caused by reduction of the fault current flowing at the substation. The establishment of proper detection method for the PV systems to detect the fault with high resistance in the high voltage distribution line has remained as an unresolved issue because PV systems cannot detect the fault by UVR recommended on the current guide line for grid interconnection. In the study, a new protection method to detect the fault for PV systems is designed by a numerical simulation. In the method, a new AND condition of voltage absolute value change and voltage phase change of the grid is adopted as a detective parameter for achieving enhancement of detective performance including the prevention of unnecessary detection in normal operation. Moreover, a new integration method of the voltage phase change is also devised to get high reliability of the detection under the high density interconnection to the grid. Simulation results indicate the number of detective PV system remarkably increases with the devised methods to improve the fault current flowing at substation in 20% to 40% as compared with conventional method. From above, applicability of the designed method to PV systems is confirmed.

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The health effect of the weak current induced in a human body exposed to the power frequency electric field has been investigated since early 1970s. In the case of the ungrounded human model, the current densities inside a human model exposed to the electric field are experimentally clarified by Kaune et al. However, the man who is near by the transmission power line is almost insulated with the ground by insulating medium, such as shoes. Until now, the current density distributions in a human model which stands on the insulating medium have been little analyzed.
In this paper, the finite element method is applied to the analysis of the current density distributions in a human model which stands with erect position on the insulating circular plate, and the characteristics of such internal current density distributions are clarified.

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Technologies necessary to produce dimethyl ether (DME) from low-quality coal have been pursued as a new project funded nationally in Japan. Methanol has long been studied as the most promising fuel for fuel cells used in transportation applications due to the ease with which this liquid fuel can be transported. But DME is the more attractive fuel due to its low toxicity and the fact that it has a higher energy density than methanol.
The present paper reports the findings of the first study ever conducted on the DME direct fuel cell. A DME direct fuel cell of 6×6cm² is demonstrated for the first time using a polymer electrolyte fuel cell. Similar to methanol, the DME cell performance is highly depend on the steam partial pressure of the fuel gas. Performance level of the cell was almost equal to that of a methanol direct fuel cell by increasing steam partial pressure of the DME by 1.5 times more than that of methanol.

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This paper presents a method of constructing Lyapunov function for multimachine co-generation system which is interconnected to the distribution system.

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