Ferography analytical method is required to detect the wear particles in the lubricating oil automatically, because in the customary way it is involved a sacrifice of a great deal of time. We propose a new method to detect the wear particles in the lubricating oil to diagnose the bearing by means of local spatial frequency analysis using Wavelet Transform. Gabor function and cylindrical Gabor function are used as the mother function of Wavelet Transform in this paper. Gabor function is effective to detect the particles which distribute along the line of magnetic force on the Ferogram slide. Cylindrical Gabor function can detect the circular particles. And to discriminate the particles, we apply the Fuzzy Systems Theory to the image transformed by two Gabor function and show the effectiveness of this method.

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After testing for the life time, the short-stack with a pressurized 1m² cells have been dismantled and analyzed for the amount of residual phosphoric acid, diameter of platinum and the amount of remaining platinum in the cell electrode. As a result, it has been learned that the current density is a dominant factor for the increase of phosphoric acid on the anode electrode substrate. The other side, increase of phosphoric acid on the cathode electrode substrate are influenced by cell operating temperature and temperature of air outlet. And cathode electorocatalyst sintering are governed mainly by operating temperature and cathode potential.
We had analyzed for causes of deteriorating the characteristics of the large area cells based on the residual amounts of phosphoric acid and retaining catalyst. As a result, it has been discovered that the influence of phosphoric acid is as dominant as that of sintering for ribbed electrode type cell.

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High voltage windings of high power transformers, have to be designed in such a way as to withstand surge voltages. From this point of view, interleaved windings have the better behaviour, but they are much more expensive with respect to continuous ones. Thus, designers and manufacturers try to use a number of interleaved section pairs as smaller as possible, located at the top of the winding. The choice of the more proper number of interleaved section pairs can be carefully made only if the mathematical model of the phenomenon is known. In the paper a mathematical model is proposed having the goal to determine the voltage-time distribution along a disc winding of a transformer, suitable for PC implementation. It takes into account not only series and ground capacitances but also resistances and inductances of winding sections. In this way, the determination both of the initial voltage distribution and of the following local oscillations is possible. The proposed model has been validated by the good agreement between theoretical and experimental results.

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In winter, the content (%) of “multi-conductor simultaneous faults” among “all the lightning faults” on double circuit transmission lines is much larger than in summer. To find a cause of the problem, many field investigations were conducted and statistics were collected. Based on these data, the author set up a new theory to estimate the probability of occurrence of multi-conductor faults during winter. This results coincide with the lightning performance of transmission lines either in summer or winter. The author's important view points which are newly introduced are followings; (1) The content (%) of large current lightnings among all the lightnings is much larger in winter than in summer (2) More than 83% of lightning flashes hit tower tops in winter, while only 25% hit tower tops in summer.

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A thyristor-controlled series compensator (TCSC) can stabilize a power system by controlling line impedance. In the future, it is expected to provide a scheme for dealing with stability problems. However, detailed reports about experimental behavior and hardware design of the TCSC are lacking regarding such fundamental points in practical use. Therefore, first, various TCSC hardware specifications are studied and a 500kVar class TCSC prototype is developed from the viewpoint of adopting the TCSC in trunk power systems. Its current rating is 500 Arms, which is about one-tenth the maximum current of the TCSC designing studies.
This paper deals with the necessary hard components for the TCSC, and in particular, specifications of the series capacitor, the configuration of the thyrister stack and the design of the protection-controlled units. Furthermore, the effectiveness of the thyristor control is evaluated by experiments. The TCSC is shown to be a useful power flow control device for large, high power transmission systems.

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Because of relatively high short circuit resistance, most of the ground fault accidents between power feeders and supporting structures can not be detected by the conventional protection systems at the DC electric railway substations. A novel protection system has been successfully developed which reduces such a short circuit resistance to the detectable level. The unit pulsed power swiching controls consists of a CR-integrator, a master pulse generator gap, a decoupling gap switch and two main arc gap switches in a series connection, and installed between the rail and the supporting structures. The large scale field test has demonstrated that these inexpensive protection systems function well and may improve the reliability of the DC railway systems.

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We have successfully put a new system into practice. The system is using a highly sensitive partial discharge (PD) method for live line power cables and automatic recognition of PD from external noise for long-distance cable lines, in order to ensure that extra-high voltage XLPE cable lines are proved to be reliable. In this system, signals from each joint in the underground tunnel are detected using a high frequency tuning method before they are optically transmitted to the master station for centralized monitoring of whole signals. The system has a primary recognition section which is composed of various analog gates and secondary section which is uses a neural network (NN) to automatically discriminate PD. The system is capable of highly sensitive(1-10pC) PD detection along the entire line. Application of the system to PD measurement in after laying test of 275kV XLPE cable lines demonstrated its automatic monitoring capabilities.

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This paper is focused on a voltage-detection-based shunt active filter for installation on a power distribution system. A main objective of the active filter is to achieve damping of harmonic propagation coming from series/parallel resonance between capacitors for power factor correction and line inductors in the distribution system. The active filter installed at the end terminal of a distribution feeder is controlled in such a way as to present infinite impedance to the external circuit for the fundamental frequency, and as to exhibit low resistance for harmonic frequencies. As a result, the active filter acts as a damping resistor for the harmonic propagation, just like a 50-Ω terminator installed at the end of a signal transmission line. It is verified by experiment that the active filter intended for harmonic termination has the capability of harmonic damping throughout the distribution feeder.

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NTT is developing a phosphoric-acid fuel-cell energy system for telecommunication co-generation systems to reduce energy costs and help preserve the environment. We have studied a thermoelectric generation system using the exhaust vapor heat from a 200kW fuel-cell, which can convert heat energy directly into electrical power. The system consists of 170°C hot-plates heated by the exhaust heat, small cooling plates connected to a heat pipe, an outdoor heat-radiating fin, and Bi-Te thermoelectric modules, which are set up between the hot-and cold-plates. This system generates power efficiently without loss of the subsidiary cooling pump power. The output power density increases with decreasing outdoor temperature and with decreasing thickness of Bi-Te. The system generates a maximum power density of 2.4kW/m² at 5°C, the lowest tested outdoor temperature, with Bi-Te thickness of 1mm. The thermoelectric conversion efficiency is 1.4 to 2.1% at 5°C in the Bi-Te thickness range from 1 to 5mm. We estimate that the thermal contact resistance is 4 to 5×10^-4m²/kW from a simulation using the thermal resistance model. Total power is estimated to be of 1.9kW for Bi-Te thickness of 5mm and 1.3kW for 1mm when using all of the exhaust vapor heat from a 200kW fuel cell. The thermoelectric module using 1-mm-thick Bi-Te generated electricity more economically than the 5-mm-thick one because it generated electricity efficiently with less Bi-Te.

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The outage ratio of pole transformers reaches to approximately 40% of total distribution line equipment outages. Then, it is necessary to develop an effective prevention method for pole transformers against lightning.
In this paper, we clarified the relation between a lightning current and an induced voltage of a pole transformer caused by lightning current, and examined the lightning protection effects of surge arresters for a pole transformer. The main results are as follows:
1)The length of the grounding conductor from an arrester to a transformer mounting bracket has a significant influence on the protection of transformers. In the case that surge arresters are installed on every second pole and the value of grounding resistance of grounding conductor is 30Ω, 80% of direct lightning hits do not damage a transformer with a 2.5m-long grounding conductor.
2)Even if the grounding resistance of the grounding conductor is as high as 200Ω, a good protection effect is obtained. In the case that surge arresters are installed on every second pole, 70% of direct lightning hits do not damage a transformer with a 2.5m-long grounding conductor.

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Lightning-induced voltages on a test distribution line had been observed near the Fukui steam power plant since 1980. From 1993 the observation was resumed on a new test line at 370m from the 200m stack of the plant. Measured induced voltage waveforms showed the characteristics of those influenced by finite ground conductivity, estimated to be higher than 10mS/m. Measured horizontal electric field waveforms were composed of narrow pulses having the duration of less than 5μs and of slowly varying components having the duration of more than 50μs. The narrow pulses were generated due to the finite ground conductivity after the onset of a large current pulse. The slow component, observed during the leader process as well as after the onset of a large current pulse, little contributed to generation of induced voltages. Some of the measured horizontal electric field waveforms associated with lightning strokes to the stack were bipolar in the submicrosecond range. This type of a field change can be attributed to the reflection and the refraction of lightning current waves at the top and the bottom of the stack.

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In this paper, we investigated alloying, crystal grain growing, annealing of copper wire to improve the SCC (Stress-Corrosion-Cracking) durability. Each treatment is effective, in particular, alloying with Ag and annealing are most effective. Varying the concentration of silver and the condition of annealing, the sample alloyed with 0.15Ag wt% and annealed under 260°C is most effective. In accelerated test, it was found that the SCC durability of this sample is improved to be 4 times larger than that of conventional copper wire. We also study the mechanism with which the SCC durability is improved. As the result, we revealed that Ag-dense layers exist. It seemed that this Ag-dense layers block the growth of oxide film and the spreading of pitting corrosion, as the result, SCC durability is improved.
Above mentioned, increase in peel strength, weakening of residual distortion stress by annealing, and preventing corrosion and pitting corrosion to spread by Ag-dense layers seemed increase the SCC durability of copper wire with combined effect.

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Since concerns have been expressed regarding the environmental effects of ELF (Extremely Low Frequency) magnetic fields, it is important to establish a method for mitigation of the magnetic fields around electric power facilities. We previously reported a method to reduce the magnetic field generated from underground cables using cylindrical shielding materials. In this paper, to gain a more practical understanding of shielding phenomena, we investigated magnetic field reduction mainly by means of numerical and analytical calculations. At first, a numerical calculation method and an approximate formula for magnetic shielding effectiveness were applied to the cylindrical shielding materials and their validity was verified. Then, the relationship between several parameters of shielding materials that affect the shielding effectiveness was clarified. A design guideline for the magnetic shielding was also proposed.

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This paper proposes a new type of continuation power flow method tracing Q-limit points where the reactive power limits of generators are encountered. The proposed method consists of the predictor scheme to estimate Q-limit points and the corrector scheme to obtain their converged solutions. The condition for Q-limit immediate instability is derived and used in the algorithm. All of them are different from the conventional schemes. The proposed method when combined with the Point of Collapse methods quite effectively provides the converged solution for the critical loading condition which is either the immediate instability point or saddle node bifurcation. This implies that the proposed method can compensate the drawbacks of the existing methods such as the Point of Collapse methods and the continuation methods. The effectiveness of the proposed method is demonstrated through numerical examinations in IEEE 118 bus system.

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Demand-Side Management (DSM) gives the utility flexible load management measures of electric power system and, to promote it to the power system, it is necessary to study the long-term cost-effectiveness of DSM programs as well as the short-term one. We have developed a prototype model of Integrated Resource Planning (IRP) to optimize dynamically the promotion of the DSM programs in the planning period in comparison with supply-side resources. The DSM program promotion costs the utility direct payment to program participants and lost revenue caused by change of load shape. Technological learning of DSM equipment is also incorporated endogenously into the model to analyze dynamical penetration of the new technology. We show the importance of technology learning in the cost-effectiveness analysis through a case study for commercial thermal storage system that are the most promising DSM program in Japan. We evaluated market penetration, cost-effectiveness of the program and the resulting effect in the power system until the year 2014.

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Power system load change and transmition line change occur frequently. System state change in any form is no doubt the major issue in power system stabilization. Controller design of thyristor controlled series capacitor (TCSC) can be formulated as a robust control problem.
In this paper, a design approach of TCSC controller is formulated. The approach is based on detail analysis of dynamic characters and practical requirements (stability margin, sensitivity, disturbance attenuation etc.) of power system. Make use of mixed-sensitivity method of H_∞ control theory, a practical controller design is proposed. A design method for weighting functions (W₁, W^-1₂, W^-1₃) is developed. It consists of design foundation and design steps. An effective TCSC controller is presented. With this designed controller, the power system can be stabilized in larger state fluctuation. Comparing with PID controller, this controller has stronger robust stability and disturbance attenuation. Simulation results show that the proposed design approach is correct and effective.

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The objective of this study is to estimate customer interruption cost by analyzing survey responses and comparative examination between it and the estimation value by the economic macro method or the example of America and Canada. The power interruption cost is considered as one of the useful index for evaluating the expansion planning or the operation of power system facilities from reliability.
It is also considered to become more important index in the recent development of integrated resource planning in which both supplier's and customer's resources are equally dealt with. This paper reports the estimation results of customer interruption costs based on the three years survey from 1992 to 1994 conducted in HOKKAIDO and for various kinds of customers.

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