This paper describes the effects of the arrangement of electrodes, the temperature of the working fluid, and the polarity of the electrode on the Electro-hydro-dynamical (EHD) generated pressure to clarify the stable operating conditions of EHD pump for realizing the vertical transportation of the dielectric liquid. The vertical type EHD pump is composed of the ring electrode and the cylindrical electrode arranged in an U type pipe filled with the dielectric liquid. The dielectric liquid such as the silicone oil is transported vertically against the gravity by applying the direct high electric field between the cylindrical electrode and the ring electrode.
The following results have been obtained experimentally. The EHD pump can transport the silicone oil steadily to the upward direction by using the ring electrode vertically placed against the cylindrical electrode. When the direct high voltage is applied at the cylindrical electrode and the ring electrode is electrically earthed, the silicone oil moves steadily toward the direction of the cylindrical electrode.

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The annealing characteristics plays a central role in studies on improvement of the operating ratio of transmission line. We rigorously evaluated and verified the annealing characteristics of new and aged ACSR. In particular, a method was identified for the accurate estimation of the annealing characteristics of the entire ACSR from the annealing characteristics of the aluminum strands. The results can be summarized as follows.
(1) When evaluating the annealing characteristics of aged conductor using aluminum strands, it is better for tensile strength measurement to untwist the strand after heating than untwist before heating.
(2) The annealing characteristics of aluminum strands vary greatly depending on manufacturing method (WB method, CC method).
(3) If manufacturing method of the aluminum strands is the same, the annealing characteristics of new and aged ACSR as a whole can be estimated accuracy from the tensile strengths of new aluminum strands (prior to heating) and aluminum strands sampled from the conductor after heating.
(4) The tensile strength of annealed aluminum strand depends on the sum total of heating (temperature xtime). The order of heating has no relation to the final tensile strength.

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A wide variety of configurations can be conceivable for a Back-to-Back (BTB) system. Investigating a BTB system configuration to adopt, consideration must be given to both cost and reliability depending on system requirements (power flow capacity, reliability, etc.), characteristics of system components (such as failure rate) and their prices. However there are few cases in which system configuration has been determined by a quantitative assessment method.
This paper presents a method for determining the optimal configuration taking into account both cost and reliability. System reliability is evaluated on the basis of reliability engineering. The cost of damage caused at the outage is formalized based on system reliability. The proposed method quantitatively assesses system configurations on the basis of the sum total of device cost and outage-damage cost, and determines the optimal configuration.
To provide an example of the technique at work, the authors defined a standard case in detail and applied the technique to it. This paper reports on the optimal configuration so obtained.

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The current-voltage characteristics I_out(V) of various kinds of solar cells, including crystalline silicon, amorphous silicon, thin-film crystalline silicon, and cadmium telluride, are experimentally investigated at various irradiance E. Their dependence on E can be well approximated by the sum of a dark current I_d and a voltagedependent photocurrent Iph, which is proportional to E. These results are used to develop translation equations. It is demonstrated that the resulting formula is able to calculate the I_out(V) of the solar cells at any E from experimental I_out(V) at two different Es, with comparable or better accuracy than the conventional procedure based on the shifted approximation. The present procedure is straightforward, and does not require correction for the series resistance. The same translation equation is valid for all kinds of solar cells investigated in this study. Although the dependence of the fill factor, open circuit voltage and conversion efficiency of various solar cells on E is not simple, it is consistently explaind by the voltage-dependence of the I_ph and I_d.

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We developed a current limiting element consists of the YBCO thin film on the sapphire substrate and the Ni film on the AIN substrate to improve a working voltage. The YBCO thin film was connected electrically to the Ni film in parallel. When the YBCO thin film changed to the normal state due to the excess current, the current diverted from the YBCO thin film to the Ni film, and the heat shock to the YBCO thin film was reduced. The working voltage per unit length was 43.3V/cm, which was three times as high as that of the element without the Ni film on AIN. And we constructed a module with six elements connected in series. When the excess current flowed in the module, all elements changed to the normal state and working voltage was at least 1.87kV.

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Abstract: This paper presents an experimental investigation on interaction between arc length. And a black box arc model based on modified Mayr arc equation is developed to describe the influence of arc length on arc voltages. In this model, the coefficient of arc power loss is defined to be depending on the arc length. The numerical analysis is performed on EMTP. The behavior of arc is represented using Thevenin type-94 component of MODELS.

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Establishing procedures for accelerated lifetime testing would promote PAFC development.
Measurement of temperature, current density, pressure and electrical potential in small size cells revealed that increasing the temperature was the best way to accelerate cell degradation. It was confirmed by the full scale short stack test of 18, 000 hours operation that voltage losses due to activating polarization and gas diffusion polarization increased with operating temperature.
Estimates of voltage losses due to catalyst degradation and gas diffusion blockage were made from both the increases in catalyst particle size and the increases of acid content in the catalyst layer during the full scale short stack test.
Based on the test results and estimates, we propose a method for accelerating lifetime tests of phosphoric acid fuel cell by increasing the operating temperature.

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Many researches and developments of the high temperature superconducting apparatus such as a transformer, a fault current limiter, a cable, etc. are being made actively in the power field in accordance with the performance advancement of the Bi silver sheath high temperature superconducting (HTS) wire. In these, an HTS transformer is considered to be one of the most promising applications in view of efficiency improvement, the interface with the cryogenic cable and the normal temperature device, incombustibility, over load capability, the function as a reactor and the possibility of a fault current limiter. The necessary technical development items of an HTS transformer in order to achieve superior performances to the conventional one are examined. For this purpose, the 3-phase 66kV-100MVA transformers are designed for the comparison of an HTS transformer and a conventional one with the oil cooling. The desirable development items are an HTS wire current density of, about 40A/mm², allowable winding strain of about 0.5%, a percent impedance of 7.5%, the air gap flux density of about 0.3T and ac losses of about 0.3W/km•A.

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Pulsed field losses in a short sample (445 mm length) of 46 kA Nb3Sn cable-in-conduit conductor of superconducting magnet for fusion experimental reactor “ITER” is measured with calorimetric method. A coupling time constant between strands is obtained as 30 ms through pulsed field losses. Based on this time constant and conductance measurement of inter-strands, it is expected that there is a coupling current loop length around 420 mm, which is longer than half of the twist pitch in the 4th cabling stage. A geometrical calculation on this complex cabling shows this value is reasonable one.

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We study the stability of persistent current switches (PCSs). In this study, we measured the thermal contraction coefficient of several samples of PCSs. The bobbins of the sample PCSs used in our experiments were made of several kinds of FRP, of glass fiber, high strength polyethylene (Dyneema) fiber, and cotton fiber. The thermal contraction coefficients of the bobbin and winding were measured by strain gages. It is found that the thermal contraction of the bobbins influenced the thermal contraction of the windings and also influenced the stability of current performance.

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As mechanical causes for instabilities and losses of superconducting coils become dominant with a scale of them, it is important to understand mechanical behaviors of them in developing a practical scale SMES with high reliability and high efficiency. But to know the mechanical behaviors in the superconducting coil, especially local deformation or displacement of components of it is difficult. Therefore it might be helpful to use a model which can simulate the mechanical behavior of superconducting coil for a discussion of the instability and mechanical loss caused by the mechanical effects.
In this paper, a simulation model which is developed for the nonlinear mechanical deformation of a modified D-shaped elemental coil with a Rutherford type conductor for a 1 kWh SMES is shown. The model uses nonlinear mechanical characteristics of the conductor measured by a 3-point bending test. The nonlinear characteristics of the conductor are explained by the frictional slip between two layers in the conductor. FEM analysis with this model agreed well with measured mechanical deformation of the coil.

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This paper proposes a new evaluation method of the kW-value of PV system which is based on the actual insolation data observed by Japan Meteorological Agency (JMA) at 4 points in Chubu area and the actual electricity load data of Chubu area in the 1990's. We selected the days on which the daily peak load was large. For the selected days, we estimated the areal average output of PV systems by using IEA method considering the temperature dependence of the cell efficiency. Then, we calculated the reduction of the peak load ΔL_P. The resultant ΔL_P was around 0.5 kW/kWp.
We evaluated the average value of smallest ΔL_P as the kW-value of PV system. When the kW-value is evaluated by the smallest two or three ΔL_P among the selected 10 days for 1 year, the kW-value of PV system is calculated to be about 30 %. This value is close to that evaluated by the conventional LOLP method. Our evaluation gave the relation between the kW-value of PV system and the number of days on which the insolation is small though the daily peak load is large.

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For the safety of human beings against lightning, it is essential to keep away from direct strikes. To establish the proper safety guide, the time intervals between subsequent flashes and the distances between subsequent struck points are the two important factors. The authors statistically analyzed the data obtained by the lightning location system, covering whole Kanto District for two years and clarified the statistical feature of the above two factors. When a person hears thunder, he should immediately refuse into a safe space, such as the interior of buildings. When a person encounters an active thunderstorm, he should keep his posture as low as possible till the storm activity diminishes.

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First, a change of the electrical property by heat degradation of XLPE sheet, which is the main insulation material of a 66kV class XLPE cable, with the passage of time, was acquired. Next, oxygen consumption, oxygen diffusion coefficient and amount of oxygen resolution were measured. The two-dimensional simulation was made and that result was compared to those data. The simulation result and those data obtained good coincidence about the lifetime of XLPE sheet. Moreover, OIT measurement of XLPE sheet, which carried out heating degradation, and life estimation of XLPE sheet was performed. The result of this and the above-mentioned simulation were compared. Consequently, it turns out that the simulation can perform life estimation of XLPE sheet enough. The 2-dimensional simulation was also made about XLPE cable insulator. This simulation predicts that lifetime of XLPE cable operated around 90°C is about ten years.

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Acid management is necessary in a phosphoric acid fuel cell to prevent an overall or localized shortages of the acid. We found that the transfer of phosphoric acid occurred when a temperature gradient was applied to the porous carbon plate in which the acid was stored. This is an important phenomenon because various temperature distributions may occur in a cell under actual operating conditions. The effect of temperature gradients was evaluated using 50 cm porous carbon plates with acid fill levels of 40%, 50%, or 60%. The temperature of one half of the specimen was maintained at 180°C, and the other at 150°C, 100°C or 50°C for 72 hours. Under these conditions, the quantity of phosphoric acid in the high temperature side of the cell measured by neutralization titration increased, and that in the cold temperature side decreased. The rate of phosphoric acid transfer increased with increases in the temperature gradient and fill level. Two phenomena were examined as potential causes of this transfer mechanism. Evaporated water from the high temperature section is considered to condense in the low temperature section, and the volume of phosphoric acid in the low temperature section increases, whereas that in the high temperature section decreases. Phosphoric acid transfer is therefore considered to occur in order to maintain proportionality of the fill level in the cell. It was found that the calculated values based on this assumption were approximately equal to measured transfer rates. It is shown that temperature dependency on the interfacial tension is not a dominant factor on the rate of acid transfer.

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The main purpose is to evaluate the effectiveness of SVC installation from the viewpoint of an energy-based index. Although transient and voltage stability - due to distinct mechanisms and separate time frames - have been perceived as decoupled phenomena by some researchers, in this work they are treated as aspects of coupled power system dynamics. The time-domain simulation uses detailed models for system components and controllers including SVC. Based on the trajectories obtained, an energy value can be calculated for every point in time. The energy function formulation is developed using injection models. The measure of stability used is the energy margin. This is computed based on the well-known second-kick method. A new second-kick design better suited for exploring voltage instability mechanisms is proposed, which consists of a combination of load step and fault. The better timing of applying a second-kick disturbance is also studied. Results are shown for a standard IEEJ test system. Energy margins and unstable equilibrium point approximations are calculated for the conventional and new second-kick designs. It is seen that the energy margin is dependent on the nature of the disturbance. SVC's are expected to improve stability by providing fast reactive power support at key load buses. Improved energy margins are observed when these devices are available.

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A large power system is often subjected to stability problem. This paper deals with the investigations regarding the transient stability enhancement of the electric power system making use of a fuzzy logic controlled braking resistor scheme. Following a fault, variable rotor speed of the generator is measured and the firing-angle of the thyristor switch in the braking resistor is determined from the crispy output of the fuzzy controller. By controlling the firing-angle of the thyristor, braking resistor can control the accelerating power in generators and thus improves the transient stability. The effectiveness of the proposed controller 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 near the generator. Moreover, the performance of the braking resistor scheme with fuzzy controller is compared to that of with the conventional PID (Proportional-Integral-Derivative) controller. Simulation results indicate the better performance of fuzzy controller in comparison with conventional PID controller. Thus, the proposed fuzzy control strategy provides a simple and effective method of transient stability enhancement.

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The Concordia-Demello model is well known method for adjusting PSS constants of tandem type of generators and widely used. However, this method is not able to analyze a cross compound generator correctly which consists of primary and secondary generators and has a local and an interarea modes. Therefore, in order to adjust PSS constants of cross compound generator, a more detail model is required. Such researches are few and an efficient methodology that grasps characteristic of cross compound PSS with sufficient accuracy is strongly desired.
In this paper, the authors propose a method using the Park's model considering the damper effects, which can be obtained by linearizing a 2 generator to infinite bus system. The proposed method uses a torque coefficient matrix obtained from the linear state equation and calculates an electric torque by using it.
Firstly, this paper reveals the difference of electric torque characteristics between a tandem and a cross compound generator. Next, it points out that conventional methods that adjust PSS constant by evaluating a primary and a secondary generator separately may give wrong results. Finally, the effectiveness of the proposed method is confirmed by using a test model.

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This paper presents the numerical results of the bifurcations and the chaotic behavior in a fundamental power system model, a single-machine infinite-bus system model with the generator excitation control by the first-order lag AVR. The numerical analysis mainly focuses on revealing the parameter value region where the chaotic behavior is observed. And it is shown that the partially linearized model, which is derived by linearizing all the nonlinear elements except the AVR limiter, exhibits the similar bifurcations and chaos. Several simulation results indicate that the mechanisms for the chaotic behaviors and the bifurcations to arise are same both in the linearized model and in the original single-machine infinite-bus system model for the parameter value variation which does not move the equilibrium point from the reference point used for the linearization.

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A Multi-input Power System Stabilizer (MPSS) was developed to improve damping of low frequency power swing in long distance power system and to expand robustness for changing power system configuration and/or operating condition.
In this paper, a setting scheme for the parameters of the MPSS is established. Moreover, the AVR with the MPSS is applied to a 100 [kVA] micro generator in CRIEPI's Power System Simulator and is compared with ΔP+Δω input type PSS. To verify the setting scheme of parameters and the power system stability improvement of the MPSS, a long distance fish bone type 4-machine infinite bus system is configured in the simulator, where complex swing modes exist with long period and poor damping.
The testing results show that the MPSS has good performance to damp low frequency power swing and to increase the power transfer limit in the power system with longer transmission line and large generator internal angle δ.

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EMTP type simulation software has difficulty on managing switching phenomena in power electronics circuits. This paper evaluates the performance of GIFU switch in ATP and CDA in Simpass from the view point of suitability to the switching transient simulation.

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This paper presents the results of analyses of the extension of the dead time by superconducting fault current limiter (SFCL). Although SFCL is generally used for the purpose of limiting of fault currents, it can also be used to stabilize synchronous generators. Therefore, as the transient stability when the fault occurs is enhanced effectively by SFCL, the reclosing time of circuit breakers can be delayed. It means the possibility of unsuccessful reclosing of circuit breakers can be lowered.

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