Recycling works of electric wire and cable material in Japan are surveyed. The recycle-ratio of conductor materials is very high, but that of covering materials is very low, about 30%. Therefore the separation technologies of covering materials have been developed; one is static electric-field separation and another is hydro-cyclones separation. The products from waste covering materials are introduced as a material recycling, the thermal recycling methods and new technologies are also mentioned.

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Phase shifter has been used to control line flow. In the network with multiple loops, it is necessary to modify the angle of phase shifter to reduce the flow on a certain line if it exceeds the limit. A new method to compute the value of the angle that is set to the phase shifter is proposed. A coefficient is computed by using two relations. The one is between the change of line flow on a certain line and the modification of power injection at two nodes. The other is between the change of flow on a line and the change of angle of phase shifter. Then the phase angle is computed by multiplying the coefficient and the amount of flow on the line. The coefficients can be used for finding the locations where phase shifters will be placed in order to correct overload that may occur at any line in the loops and can be used for computation of available transmission capacity. The validity of this method was shown by numerical examples using IEEE 30 bus system.

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We propose an optical current sensing system which has a function of the differential electric current calculation being done in the protective relay equipment. In the proposed system a new scheme of common pass fiber-optic interferometer is formed. The interferometer is composed of the flint glass fiber as multiple Faraday sensing elements, quarter wave plates as polarization mode converters, and polarization maintaining fiber as signal transmission lines. By using this system, stable output proportional to the total value of current detected by the multiple sensing elements can be obtained. In order to confirm the principle, an experimental set up including three sensors was built and characteristics of the system were examined. From results of the experiment, it became clear that function of the experimental system agreed well with the principle. Following the successful experimental results, two basic model sensors for practical use were manufactured and were incorporated into the system. Good test results of the system with the model sensors were also obtained.

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This paper examines the implications of changing of operating mode or duration of contract of independent power producers in power sector planning in Indonesia. In particular, an approach is developed to assess the contributions of supply- and demand-side effects to the changes in CO₂, SO₂ and NO_x emissions from the power sector due to changing of operating mode or duration of contract of independent power producers. The results show that the supply side effect would increase the CO₂, SO₂ and NO_x mitigations, however, the demand side effect would act in the opposite direction. The results also show that the CO₂, SO₂ and NO_x emission mitigations would increase if the operating mode or duration of contract is increased from 60 to 80% or from 5 to 15 years respectively.

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This paper presents an EMTP simulation model for the wind turbine generator using induction generator. This model was developed to add the model of a wind turbine portion to the precision model using the standard specification data and operation data of induction generator. It verified that the inrush current at starting and the residual voltage at islanding state were analyzed, and measured data could be reproduced by this model.

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Due to the diversity of the distributed generators (DGs) such as a photovoltaic power generation system, a fuel cell, etc., the control of the future distribution system is expected to be complicated. We have proposed a new control scheme of DGs which utilizes the information on other load buses and or DGs to improve the system reliability, and have shown new technical advantages over the conventional system. In this paper, we focused on the load leveling by DGs, where DGs compensate the load fluctuation of the distribution system by their autonomous control. We propose a new control scheme of DGs, where the information on the power flow at the distribution substation and their own load bus is utilized, and the control parameters are tuned autonomously depending on the load fluctuation patterns. The simulation using the simple distribution model with 3 load buses and 2 DGs have revealed that the various types of the load fluctuations are suppressed successfully.

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Fuzzy logic has been gaining increasing acceptance in control applications during the past few years. Usually, the membership functions and control rules of fuzzy logic controller are determined by trial and error which is cumbersome and time consuming. Therefore, to surmount such a drawback, this paper makes use of the Genetic Algorithm (GA) technique for optimal tuning of the parameters of the Fuzzy Logic Controller (FLC) used for the switching of the thyristor controlled braking resistor to improve power system transient stability. The braking resistor is installed at each generator bus, where rotor speed of the generator is measured to determine the firing-angle of the thyristor switch. By controlling the firing-angle of the thyristor, braking resistor controls the accelerating power in generators and thus improves the transient stability. The effectiveness of the proposed method has been demonstrated by considering both balanced (3LG: Three-phase-to-ground) and unbalanced (1LG: Single-line-to ground, 2LG: Double-line-to ground and 2LS: Line-to-line) faults at different points in a multi-machine power system.

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The authors have proposed a new concept of a distribution system ‘Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)’ with a view of solving problems in near future and providing several services for electric companies and customers. The main idea of FRIENDS is to install new facilities named Quality Control Center (QCC) in the neighborhood of customers to realize various functions, e.g. Customized Power Quality Service. In addition, these QCCs make a network of electricity and information below distribution substations. The configuration of the network can be changed frequently depending on the system and load conditions. This frequent reconfiguration of the network requires fast and reliable Transfer Switching in QCC to ease an effect on customers. The reconfiguration with the aim of removing a fault wire also requires fast Fault Detection. This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in an ordinary state, and even in a fault. Besides, this paper analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC.

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In recent years, Fuel Cell Electrical Vehicle is expected to improve urban environment. Particularly a hydrogen fuel type FCEV expected for urban use, because its excellent characters such as short startup time, high responsibility and zero emission. On the other hand, as far as hydrogen production is concerned, large amount of CO₂ is exhausted into the atmosphere by the process of LNG reforming. In our research, we studied the utilization of LNG latent heat for hydrogen gas production process as well as liquefied hydrogen process. Furthermore, CO₂---Capturing as liquid state or solid state from hydrogen gas production process by LNG is also studied. Results of research shows that LNG latent heat is very effect to cool hydrogen gas for conventional hydrogen liquefied process. However, the LNG latent heat is not available for LNG reforming process. If we want to use LNG latent heat for this process, we have to develop new hydrogen gas produce process. In this new method, both hydrogen and CO₂ is cooled by LNG directly, and CO₂ is removed from the reforming gas. In order to make this method practical, we should develop a new type heat-exchanger to prevent solid CO₂ from interfering the performance of it.

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In order to test the hot-line insulation of low-voltage house wiring, we usually measure the earth leakage current with a clamp-type current transformer (CT) through which a bunch of main line (two wire line) is placed at the service entrance. In this method, however, the measured value includes not only the effective component to be measured, but also the inductive components of the current due to the capacitance of house wiring to the earth and the load current. Generally, the effective component is small compared to the sum of the inductive component. Therefore, in order to obtain correct measured values, it is essential to develop a technique to remove these inductive components.In order to remove the inductive component due to the load current, we have developed a bypass function element (hereinafter called as breaker attachment) that is applied to a circuit braker equipped at service entrance or branch points. As for the removal of the capasitive current to the earth, the DFT method has been introduced to the measurement using the so-called hyperbolic function method that was developed before. This hot-line insulation measurenent equipment is capabable of measuring the insulation measurement of 10 MΩ within the error of less than ± 5% under the conditions of load current of 10A and capacitance to the earth of 0.08 μF.

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A unique method of predicting lightning outage rates for substations, taking into account statistics-based lightning characteristics, has been developed. The proposed method features the application of two processes in combination: a high-accuracy lightning surge analysis applying the electro-magnetic transient program (EMTP); and a statistical data analysis using general spreadsheet software. By employing an original tool applying the proposed prediction method, which is installed in a personal computer, optimal substation lightning protection can be designed. In this paper, several analysis models are proposed for lightning characteristics including lightning surge. The validity of the proposed method was achieved by comparing the transmission line outage rates derived by the models with the outage data gained during actual observations. It was found that the predicted lightning outage rates for 500 kV substations were relatively low, and this finding revealed that it is possible to decrease the impulse withstand voltage level (LIWV).

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Lightning strikes on bulk transmission lines and distribution lines frequently cause serious accidents involving electrical apparatus. It is strongly desired to analyze transient performance in terms of the transient electric potential, transient current, and transient grounding resistance of grounding systems of electrical apparatus in order to establish accident prevention. The transmission line approach, which was brought to practical applicability by Sunde and the electromagnetic field approach based on the method of moments have been conventionally used to analyze the transient performance, however, both are insufficient in general practical usage because the former can only deal with TEM waves and the latter can only analyze grounding systems in homogeneous earth. Hence, one of the authors has already proposed a novel method for computational analysis of transient performance based on the finite-difference time-domain, (FD-TD) method (FD-TD CMTP).This paper presents both experimental results of transient performance with respect to a grounding electrode of a rectangular parallelepiped electrode, which is a model of a foot of the transmission towers, and a square loop electrode, which is an element of a grounding grid, and the calculated results obtained using FD-TD CMTP. The calculated results agree very well with experimental results. This confirms the validity of using FD-TD CMTP to analyze transient performance of grounding systems of electrical apparatus.The FD-TD CMTP is expected to facilitate the rational design of grounding systems.

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Superconducting Generator (SCG) has many advantages such as small size, high generation efficiency, low impedance, and so on. An improved power system with many potential good properties may be obtained by introduction of SCG. In order to study the behaviors of SCG in power systems, a digital type SCG model for an existing analog type real-time power system simulator is developed in this work, which is suitable for real-time simulations when the generator constants and control systems are changed frequently. By use of the above-mentioned equipments, real-time simulation in cases of SCG with different generator constants and in case of SCG in multi-machine power system has been conducted. The real-time simulation results verify the effects of SCG on power system stability enhancement and show the influence of generator constants on its stability-improving effects.

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We have already developed a countermeasure against the wind noises from insulator strings of 500 kV (or less) overhead transmission lines. However, this countermeasure could not work effectively on insulator strings of 1000 kV overhead transmission lines. This is because that (1) The insulator strings consist of the High Strength Anti Pollution Insulator, which has deep ribs and the size is largest class in domestic use. (2) Insulator string length is approx. twice as long as that of 500 kV lines. (3) The 1000 kV overhead transmission lines sometimes locate at the remarkable strong wind area.
This paper presents the analysis results that can explain the reason of insufficiency of the countermeasure for the 1000 kV lines.In order to clarify these phenomena, we measured following items. (1) The fluctuation of wind velocity around the insulator unit (2) The oscillation of each part of insulator unit (3) The acoustic characteristics of insulator string.
Consequently, we could obtain the following three elements, which were deeply related to generation of wind noises. (1) The cavity tone at outermost rib. (2) The sound resonance of each insulator unit in the string allocated at equal interval. (3) The oscillation of each insulator unit. We could improve no amplified wind noises by mutual interference of these three elements.
Moreover, we developed “Waveform Sheet” confirmed that it had prominent effect to reduce wind noise generated from insulator strings of a 1000 kV overhead transmission line.

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We analyzed the statics of dielectric breakdown failures caused by water tree degradation in 6 kV XLPE cables using the Hazard Analysis. The data used in this report are actual situation of XLPE cables. The data are classified by conductor size. The failure rates were calculated, and are different according to the conductor size. Furthermore, the failure rates were calculated based on the information of conductor size, cable length and cable age in this report, resulting that the order of the priority of degradation diagnosis can be made quantitatively.

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In this study, a thermomagnetic engine is developed in order to recover the energy from the exhaust heat source. This engine can directly convert low grade energy into kinetic energy. The engine essentially consists of a rotor made of temperature sensitive magnetic material and a permanent magnet. When an object made of this material has temperature distribution in the magnetic field, the force is generated to the direction from the low temperature side to the high temperature side due to magnetic pressure.
This paper is described for the fundamental performance of the thermomagnetic engine. The magnetic shunt alloy with the large temperature gradient of magnetic flux density was used as the temperature sensitive magnetic material. The performance characteristics such as power, torque and resistance, and the relation between the temperature of the rotor and the rotation speed are measured. The net power is a maximum value of 0.3 W at the rotation speed of 0.15 rps. The resistance loss is of 0.18 W at the maximum point of the power characteristic, so the total power is estimated to be of 0.47 W. A heat transfer coefficient using the temperature of the rotor is calculated.

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This paper has investigated a surge propagation characteristic on a crossbonded cable by applying a homogeneous model in comparison with a normal-bonded cable. It has been found that the former is basically determined by the inter-core mode of propagation and results in a surge voltage becoming a rather smooth and sinusoidal-like waveshape of which the oscillating frequency corresponds to the propagation velocity of the mode. On the contrary, the latter is dominated by the coaxial mode, i.e. the core-to-sheath mode, on each phase, and the surge voltage is square-like. The propagation velocity of the inter-core mode is roughly given as a difference between the coaxial and the earth-return mode velocities, and thus is smaller than the coaxial mode velocity. The maximum overvoltage on the crossbonded cable is greater than that on the normal-bonded cable in a tunnel-installed cable as is well-known, while the former has been found to be smaller in a directly buried underground cable.

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In this paper we examine the merits that a practical photovoltaic system combining photovoltaic generation with storage batteries would provide if used in ordinary residences. Various configurations and operation methods could be envisaged for such a system. In this research we examined the optimal battery capacity, operation methods, and economic effects for a system emphasizing economical merits for the user. We first calculated the hourly amount of photovoltaic generated electricity each month, and used data on average load patterns from actual measurements to calculate battery capacity. Next, taking battery capacity and photovoltaic module capacity/price as parameters, we calculated and evaluated the economic merits for ordinary residences. The results showed that the optimal battery capacity for combination with 3 or 5 kW photovoltaic generation is around 10 kWh, and that a combined system provides merits even though it entails higher photovoltaic module costs than the use of photovoltaic generation alone.

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We have developed a novel computational simulator for a photovoltaic (PV) power generation system as an efficient design tool. The developed simulator enables us to predict the complicated performance of the whole PV system with high accuracy at short time intervals and evaluate the system quantitatively. In this paper, using the developed simulator, we quantitatively estimate the changes of PV current, battery voltage, battery discharging current, commercial supply current, and the period of practicable stand-alone operation, etc., according to the reduction of PV/battery capacity. To confirm the validity of the developed simulator, we compare the calculated values with measured ones. The computational results precisely agree with the measured values under various PV/battery capacity conditions. Furthermore, altering PV/battery capacity in the simulation, we successfully predict the system performance, e.g., the period of practicable stand-alone operation, and evaluate the PV system parameters.

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