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For ultra‐high‐voltage (UHV) systems together with high‐voltage facilities, more rationalized insulation coordination and equipment design are required. To this end, making large‐scale and long‐term field lightning‐strike observations, large amount of and practical experiments, and introducing new analysis techniques have enabled the development of advanced technologies capable of transforming conventional techniques. This paper reviews what has been developed in a Japanese electric power company in this regard. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The Japan Electric Power Exchange (JEPX) provides a platform for the trading of electric energy in a manner similar to more traditional financial markets. As the number of market agents increase, there is an increasing need for effective price-forecasting models. Electricity price data are observed to exhibit periods of relatively stable, i.e., low-magnitude, low-variance prices interspersed with periods of higher prices accompanied by larger uncertainty. The price data time series therefore exhibits a temporal non-stationarity characteristic that is difficult to capture with typical time series modeling frameworks. In this paper, we implement models for the occurrence of price spike events where spikes are defined as observing prices above a predefined threshold set here at 25 JPY/kWh. This value corresponds to about the 90th percentile of observed prices during peak trading periods. The price spikes time series is observed to be rare events that occur in clusters. We therefore propose to model the data as a Hawkes process whereby the occurrence of a spike event increases the probability of observing more spikes in the period immediately following a price spike event. We test two variations of the classical Hawkes model: the first variation models the change in the magnitude of the underlying intensity as a function of the magnitude of the price spike while the second variation models the change in the decay rate of the underlying intensity as a function of the magnitude of the price spike. An analysis of the performance of the models based on the mean absolute error (MAE) of the spike occurrence probability, a weighted accuracy index, and the Matthews correlation coefficient (MCC) metrics shows the effectiveness of the variable magnitude variation of the Hawkes model in generating short-term forecasts of the occurrence of price spike events. The modified Hawkes model especially outperforms other candidate models as the length of the forecasting horizon increases. [ABSTRACT FROM AUTHOR]

The electric power propulsion is becoming the important development direction of ship propulsion technology recent years, as it is conducive to the realization of automation, intelligence, reduced noise, enhanced propulsion efficiency, high power density, flexible arrangement, and energy saving. The good fault‐tolerant capacity and robustness of the fault‐tolerant permanent magnet motor (FTPMM) make it a potentially highly effective and economical propulsion motor in the electric power propulsion ship than other alternatives. In this paper, the structure and mathematical model of FTPMM are analyzed and the improved sliding mode observer (SMO) is constructed according to the deviation between the observed currents and actual currents. Combined with model reference adaptive control (MRAC) method and the phase‐lock loop (PLL), the switch function is replaced by the continuous Sigmoid function to reduce the chattering and finally the rotor position estimated accuracy is improved. When the motor winding open‐circuit and short‐circuit fault occur, the current vector fault‐tolerant control strategy is introduced into the improved SMO algorithm, and the rotor position is estimated accurately under faulty conditions. Finally, the proposed improved SMO position estimation algorithm under healthy and faulty conditions is verified in Matlab/Simulink. The FTPMM position sensorless technology would play a critical role in the electric power propulsion ship, and may have a profound impact on the high‐performance advanced ships and green shipping industry as well. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Because of the significant changes in environmental policies and electric power deregulation in the last decade, a lot of photovoltaic generations (PV) have been and will be installed into the power system in Japan and the ratio of PVs to other synchronous generators will be increased. As a countermeasure against the decrease in the rotational inertia in the whole power system, a virtual synchronous generator (VSG) model control of the PV has so far been proposed. However, the system stabilization effect of the VSG in large‐scale power systems has been unclear. In this paper, a virtual step‐out blocking method of VSG for improving the transient stability is proposed. In addition, the necessity of governor control of VSG in a large‐scale power system is discussed. Finally, the rated kw and kwh capacities of the battery required for realizing the VSG‐model control are evaluated. [ABSTRACT FROM AUTHOR]

SUMMARY Because of significant change in environmental policies and electric power deregulation in the last decades, a lot of photovoltaic (PV) generations have so far been installed to the power system in Japan. When a huge amount of PVs generation is installed into the power system, we are very much concerned that the disconnection of the PVs due to a system fault has a big impact on the power system stability and transient voltage stability. So it is important to equip the PV with Fault Ride Through (FRT) function in order to maintain power supply-demand balance. In addition, Dynamic Voltage Support (DVS) function of the PV is effective to recover the voltage after the system fault. However, it is unclear how the PVs which are equipped with the FRT and DVS functions affect transient stability and voltage stability. In this paper, how the power factor of the PV power output affects the power system after a system fault is analyzed using P- δ curve. Then, a new PV power factor control method for improving the transient stability is proposed and its effectiveness is shown by digital simulations on a simple power system model. [ABSTRACT FROM AUTHOR]

Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009-2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Because of the deregulation of electric power, electricity supply has changed from an exclusive supply by general electric utilities in each region to a competitive supply by various electric utilities. Furthermore, the wholesale electric power exchange (EPX) has been established, and it is becoming possible to procure and sell electricity through the market. Because the prices in the EPX are uncertain, a planning method considering the uncertainty is needed. A community energy management system (CEMS) stands between energy consumers in the community and energy suppliers. A CEMS purchases energy from external power supply sources and operates the equipment to provide ancillary service to consumers. In this paper, we consider the day‐ahead scheduling problem of a CEMS group using stochastic optimization. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The development of a wind turbine generator system in Japan is regarded as a promising source of clean energy, and its popularization is rapidly increasing. In Japan, there are many wind turbine generator systems installed on the Sea of Japan coast, with large wind capacity. However, since the Sea of Japan coast is a region with abundant winter lightning, a phenomenon peculiar to Japan, the wind turbine generator systems are subject to damage from winter lightning. Thus, it is important to observe the lightning currents striking wind turbine generator systems in order to provide lightning protection. The authors therefore installed currents sensors (Rogowski coils) on wind turbine generators installed in Hokkaido and Kagoshima Prefectures, and performed waveform observation of lightning stroke current in the winter of 2002 and the summer of 2003. These observations yielded a few current waveforms for lightning striking wind turbine generators. This paper describes the investigation and presents the observation results. [ABSTRACT FROM AUTHOR]

This paper utilizes a fixed-effects model of panel data analysis and estimates the translog cost function of the Japanese electric power industry from 1978 to 1998. First, we investigate whether the Japanese electric power industry is naturally monopolistic. We find that all electric power companies still benefit from both scale and scope economies and therefore, this industry remains a naturally mono-polistic industry. Second, in order to apply the idea of yardstick-type competition to a naturally monopolistic industry where costs are quite different between companies, we introduce two kinds of cost-comparison coefficients, one for the individually specific effects and the other for scale and scope economies.JEL classification codes: L51, L94. [ABSTRACT FROM AUTHOR]

In Japan, electric power utilities purchase electricity from independent power producers (IPPs) through competitive bidding; the IPP evaluation is based on the avoided costs of corresponding generators of utilities. In this evaluation, however, nonpricing factors such as power flow constraints in the electric power system cannot be considered. In this paper, we propose a new approach to evaluate economic impacts of IPPs, the IPP electricity being priced on the basis of total generating costs of the electric power utilities. Such a price to purchase the electricity of IPPs is referred to as the “break-even cost.” The main results are summarized as follows: 1) Break-even cost depends on not only the power flow constraints in the system, but also various IPP factors such as generating pattern, location, and capacity, 2) Break-even cost for the base-type IPP is higher than the avoided cost of corresponding utility generators, because IPPs located on demand sides can reduce the transmission power loss in the electric power system, 3) Break-even cost is affected by available capacity of utility generators, especially for the peak-type IPP generating only during peak demand periods. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 20–30, 2000 [ABSTRACT FROM AUTHOR]

Load forecasting is an essential task in the operation management of a power system. Electric power companies utilize short-term load forecasting (STLF) technology to make reasonable power generation plans. A forecasting model with low prediction errors helps reduce operating costs and risks for the operators. In recent years, machine learning has become one of the most popular technologies for load forecasting. In this paper, a two-stage STLF model based on long short-term memory (LSTM) and multilayer perceptron (MLP), which improves the forecasting accuracy over the entire time horizon, is proposed. In the first stage, a sequence-to-sequence (seq2seq) architecture, which can handle a multi-sequence of input to extract more features of historical data than that of single sequence, is used to make multistep predictions. In the second stage, the MLP is used for residual modification by perceiving other information that the LSTM cannot. To construct the model, we collected the electrical load, calendar, and meteorological records of Kanto region in Japan for four years. Unlike other LSTM-based hybrid architectures, the proposed model uses two independent neural networks instead of making the neural network deeper by concatenating a series of LSTM cells and convolutional neural networks (CNNs). Therefore, the proposed model is easy to be trained and more interpretable. The seq2seq module performs well in the first few hours of the predictions. The MLP inherits the advantage of the seq2seq module and improves the results by feeding artificially selected features both from historical data and information of the target day. Compared to the LSTM-AM model and single MLP model, the mean absolute percentage error (MAPE) of the proposed model decreases from 2.82% and 2.65% to 2%, respectively. The results demonstrate that the MLP helps improve the prediction accuracy of seq2seq module and the proposed model achieves better performance than other popular models. In addition, this paper also reveals the reason why the MLP achieves the improvement. [ABSTRACT FROM AUTHOR]

The ringing choke converter is widely used as an electronic power supply with a small capacity. A number of works have been published on the feedback systems for adjustment of output voltage. NO sufficient analysis, however, has been undertaken on the static and dynamic characteristics. In this paper, a nonlinear differential equation describing the basic operation is first derived. Next, from a small signal model obtained from this differential equation, a loop transfer function of the converter is derived. Further, the transfer function for an input variation and a load variation under regulation have been derived. As a result, the characteristic equation becomes linear and it is shown that the converter is extremely stable. The dynamic characteristic parameters of the ringing choke converter are found different from those of the conventional reactor current discontinuity mode converter. Both the gain bandwidth product of the loop transfer function and that of the transfer function of the output voltage fluctuations for the input voltage fluctuations under regulation are smaller in the ringing choke converter than in the reactor current discontinuous mode converter. It is found that the ringing choke converter is less susceptible to the input voltage fluctuations and operates with a greater stability than the reactor current discontinuous mode converter. [ABSTRACT FROM AUTHOR]

The growing demand for electricity, driven by factors such as the shift to carbon neutrality and economic growth, is a challenge shared by South Korea and Japan. South Korea, a peninsula nation, and Japan, an island country, which are both heavily dependent on foreign energy sources and have manufacturing-based industrial structures, are actively working to secure stable power supplies for their economic development. This article carries out a quantitative analysis of the roles of the South Korean and Japanese electric power sectors (EPSs) in their respective economies, seeking to identify differences and generate actionable insights for decision making and policy formulation. Utilizing the input–output (IO) technique with the latest available data, the analysis includes a demand-side model, a supply-side model, and a price-side model to examine various effects of the EPSs. The key findings reveal differences in the production-inducing, value-added creation, and job-creation effects between the two countries, highlighting operational disparities in their electricity sectors. Additionally, South Korea exhibits higher wage-inducing, supply shortage, and price-side effects than Japan, because of its public enterprise-oriented high-wage structure and a substantial manufacturing sector. These quantitative results provide valuable reference material for future government decisions and policy development in the EPS and emphasize the significant role and impact of the power sector in both countries. [ABSTRACT FROM AUTHOR]

SUMMARY Reducing the rates of nuclear power generation for all electric power sources has been seriously discussed in Japan since the accident at the Fukushima No. 1 nuclear power plant in March 2011. Thus, the distributed power supply is expected to expand. The local production of safe and clean energy for local consumption is greatly needed in Japan. In this paper, the Saroma Lake green microgrid (SLMG), a fuel cell microgrid using tidal power generation and photovoltaics, has been planned. Energy balance equations were used to investigate this system's method of operation. Further simulated analysis of the facility, its operation cost, and the electric power quality of the network were conducted using MATLAB/Simulink, and the relationships among the capacity of a facility, the cost, and supply rate of green energy and the electric power quality (interphase voltage, frequency, and higher harmonic wave) of the power network were clarified. The total projected cost of the equipment and operation for introducing the proposed SLMG is ¥1,500,000,000/10 years. Increasing the supply rate of green energy and reducing the facility cost will require the introduction of biofuels and the reduction of the facility costs of solid oxide fuel cells in the SLMG. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

HTS cable demonstration project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has started in Japan. The target of this project is to operate a 66 kV, 200 MVA HTS cable in the live network of Tokyo Electric Power Company in order to demonstrate its reliability and stable operation. The design of the HTS cable with DI-BSCCO has been completed as well as those of a termination and a joint. A 30-meter HTS cable system with terminations, a joint and a cooling system was installed in SEI facility to confirm their design and performance. Various tests as voltage tests, nominal and over current tests, heat cycle tests, heat loss measurements and so on were conducted and it is verified that the cable has good performances as design. This paper describes the design and test results of a 30-meter HTS cable, and discusses required test items of HTS cables. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including electric power standards, the status of the nuclear power sector in Japan, the automobile recall conducted by car maker Volkswagen in 2013.

The Yamada-type wind turbine was the sole mass produced small scale wind turbine produced during the mid Showa period of Japan. The Yamada-type wind turbines were used all over Japan, particularly in the north Hokkaido and Tohoku area, in the era of post World War II. Although it is thought that the experience and knowledge derived from them is very useful for further development of small scale wind turbines, there are few reports on them. In this paper, the authors investigate the Yamada-type wind turbine and Mr. Yamada himself from the aspect of history of technology. [ABSTRACT FROM AUTHOR]

The rapid spread of CHP systems will put pressure on the regional power system to require an examination of the power and heat output of CHP systems. When considering the countrywide potential of the CHP system, one should examine such a system in coordination with the grid power system. It is essential to calculate the heat and power demand at end-use level. In this paper, annual heat and power demands of end-use sectors are forecast to the year 2025 based on 20-year data. Regression analysis is used. Estimated annual demands are divided into the seasonal hourly demands considering demand characteristics. Daily load curves of heat and power demands are determined for the Japanese end-use sectors, and the annual changes of such demands are shown by duration curves of heat-to-power ratios. Moreover, the grid power daily load curves are computed numerically from the estimated heat and power demands for the manufacturing, residential, and commercial sectors. Such load curves also consider self-generated power for the manufacturing industry and self-consumption of the grid power. Estimating heat and power demands allows for a joint analysis between the power system and the future phasing in of CHP systems. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 18–30, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20162 [ABSTRACT FROM AUTHOR]

Abstract: Since the development of the first theories for the active power filters (APF) control, many efforts have been concentrated to improve their performances because the number of non-linear loads did not stop to increase. Moreover, the appearance of non-linear load of different types, three-phase or single-phase, provokes unbalanced system, which requires more elaborated controls especially in term of robustness. For the unbalanced non-linear loads, the reduction of neutral current is one of the two aims of different APF''s controls studied in this paper. This will be highly appreciated by the distribution networks. The second aim is naturally to obtain an acceptable THD for each line current. In this paper, three control methods, all based on the instantaneous powers theory introduced by H. Akagi [H. Akagi, Y. Kanazawa, A. Nabae, Generalized theory of the instantaneous reactive power in three-phase circuits, in: Proceedings of International Power Electronics Conference, Tokyo, Japan (1983) 1375–1386.] are compared and advantages and drawbacks of each approach are discussed. Then, the improvements will be presented for these controls so as to obtain better results in case of unbalanced system. The simulation results will show the effectiveness of these improvements. Finally, in order to improve again the performances of APF, a new control is proposed. This approach is based on the use of synchronous reference frame and its effectiveness will be validated through numerical simulations. [Copyright &y& Elsevier]

Retail competition in the electric power market was introduced in Japan in March 2000. Although the liberalization is limited to a part of the retail power market having about 30% of the total electricity demand, the liberalized customer segment is now subject to competition among the utilities and new entrants. This paper examines the profitability of competitive pricing for eligible segmented customers through a scenario-based model analysis focusing on the demand characteristics of segmented customers. The model includes the utility's investment in power generation for segmented customers, considering long-term rather than short-term profitability. Load leveling is not always achieved under profit-maximizing behavior of the utility because the profitability of competitive pricing depends on load patterns of bypassed customers and price differentials among power suppliers. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(4): 43–52, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10111 [ABSTRACT FROM AUTHOR]

For electric power suppliers, the stability of power supply is a most important and keen issue. Regarding this, a power grid generally becomes more stable with an increase in size. In addition, a grid is more robust when it takes the form of a circle than when it is one-directional. On this point, Japan is not a good country to maintain a stable power grid for many reasons. First, Japan is a small but long archipelago. While its length reaches about 3500 km, its width is only 300 km at the widest point. Secondly, two different commercial power frequencies are used; western Japan uses 60 Hz, while the eastern half uses 50 Hz. Thirdly, Japan is an isolated country surrounded by the Pacific Ocean, Japan Sea, Sea of Okhotsk, East China Sea, and Philippine Sea. Fourthly, building a large international circular power grid is also difficult because of geopolitical situations. [ABSTRACT FROM AUTHOR]

When electric power supply interruption is caused by a fault, it is imperative to restore the power system promptly to an optimal target configuration after the fault. The problem of obtaining a target system is referred to as power system restoration. Both mathematical programming (MP) and expert system (ES) have been used to solve restoration problems. However, existing approaches based on their MP and ES are effective in that they can utilize expert knowledge, maintenance of large-scale ES requires inordinate effort. This paper proposes a new approach to power system restoration that utilizes both methodologies so as to exploit both system' advantages. That is, a system under study is decomposed into a set of subsystems based on the knowledge of restoration experts, which is realized as an expert system. Then, MP is applied to each decomposed subsystem to obtain an optimal target configuration. A feasible operation sequence leading to the target configuration is generated by ES. This approach reduces significantly the computation time required to obtain target systems and is far less than would be the case if the total system is solved (as a unity). Moreover, the number of rules in the knowledge-base are greatly decreased. [ABSTRACT FROM AUTHOR]

A power system is configured from generating plants, substations, consumers and the transmission lines that tie them together. To perform inspection, maintenance and expansion of these facilities, regular and systematic outage of this system must be conducted. Moreover, the organization that manages this power system is a hierarchy that comprises various levels. To prepare a comprehensive schedule from the various outage requests submitted by the many sections, it is necessary for the engineer to investigate thousands of outage requests based on reliability of the power system, economical supply of power, and personnel safety. This paper presents a computerized support system that has been developed to support a coordinating engineer in power system outage scheduling. The user interface expressed as fuzzy expressions ‘Fuzzy User Interface’ that comprises an operator model of the coordinating engineer based on analysis of such work performed at a dispatching center is discussed. [ABSTRACT FROM AUTHOR]

There has been increasing interest recently in code division multiplex (CDM) systems. The authors reported a CDM system using pseudo-orthogonal Manchester-coded M-sequence pairs. For this CDM system, the effective energy per bit in the received signals is reduced (M + 1)/2M times as much as the transmitted energy per bit. Moreover, the bit error rate (BER) of the 3M-plex system, which uses the ‘a-chip-shift’ multiplex operation alone, does not converge on zero even if Eb/No increases. This paper proposes a CDM system using Manchester-coded orthogonal sequences which consists of an M-sequence M chip and an additional chip. The proposed 3M-plex system is a combination of the ‘a-chip-shift’ multiplex operation and the amplitude multiplex operation. The proposed systems do not have loss of the effective received signal energy. The BER of the proposed systems converges to zero with increasing Eb/No. Moreover, the proposed system out performs the Manchester-coded multilevel transmission system. [ABSTRACT FROM AUTHOR]

This paper discusses enactment and enforcing processes of the Japanese renewables Feed in Tariff (FIT) Law and its amendment of 2017. Thanks to the introduction FIT in 2012, the installed capacity of renewable energy is growing rapidly. As of 2015, the renewable electricity ratio in the generated electric power amount of Japan is 14.6 percent. Meanwhile, the levy burden (surcharge) reached JPY 2.1 trillion (aprx. USD18.7 billion). Through the enactment process of the FIT Law, the upper limit of the burden initially determined by the Japanese Diet was removed. A fundamental measure could not be taken to control the installation and the burden since the law does not allow for revisions on the system based on the results of renewable installation, even if the financial burden increases rapidly. Therefore, the Japanese Diet weakened the efficiency of the FIT Law in Japan. [ABSTRACT FROM AUTHOR]

Short‐circuit accidents hinder the supply of electric power in distribution lines. If a short‐circuit occurs, the power supply is interrupted and can be resumed only after the short‐circuit point is repaired. Identifying the short‐circuit point is time consuming because it is necessary to confirm whether the overcurrent passage indicator is operating and visually confirm the short‐circuit point. Therefore, we propose a method of installing an abnormal detection line under the high‐voltage line and identifying the short‐circuit point based on the current ratio before and after the short‐circuit flowing to the current‐measuring devices installed at both ends of the abnormal detection line. Because the current flowing in a high‐voltage distribution line at the time of the short‐circuit depends on the short‐circuit resistance value, the range of application of the short‐circuit resistance value is also discussed. We show that the method using abnormal‐detection lines can be applied to estimate the high‐resistance ground faults and disconnection points, and the ability to estimate short‐circuit points leads to the efficient use of the method using abnormal detection lines. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This article examines recent controversies in Japan surrounding access to the power grid by renewable energy producers to think through the possibilities of a political ecology of socio-technical systems. Beginning in summer 2016, regional power utilities across Japan began denying applications from renewable energy producers seeking access to the grid because it was "at capacity." Questions about what constituted "capacity," how and by whom capacity was determined, and what energy sources were given preferential access to the grid were significant topics of contention among renewables developers, solar advocates, power utility administrators, and central government bureaucrats. On days with excess sun or wind and low power demand, renewables producers have also been denied access to maintain grid stability. Bringing together literature on the material politics of socio-technical systems and the political economy of electric power, this article examines the grid as a networked infrastructure with its own intrinsic materiality that shapes the trajectories of renewable energy transitions. It draws on interviews with central government policymakers, utility representatives, and renewables advocates to argue that regional grid operators appeal to technical constraints to restrict the amount of renewable energy on the power grid and safeguard fixed capital investments in nuclear power. It highlights the role of expertise and counter-expertise in these disputes and calls for greater attention to how the materiality of the power grid shapes the political dynamics of renewable energy transitions. [ABSTRACT FROM AUTHOR]

Large-capacity photovoltaic ( PV) systems will be installed in future power systems. According to Japan's energy outlook, the target capacity of PV systems for 2030 is about 50 GW. When large-volume PV systems are installed in a power system, the reverse power flow from PV systems may cause a surplus of electric power. To utilize the surplus electric power without reduction of PV power generation, the operation of customer equipment such as heat pump water heaters ( HPWH) according to PV power generation is expected to be one of the solutions. In this paper, a method of cooperative control of customer equipment with PV power generation is proposed, and the effectiveness of the proposed control is evaluated by simulation analyses. [ABSTRACT FROM AUTHOR]

The Great East Japan Earthquake and the subsequent tsunami that hit and severely damaged the Fukushima Daiichi Nuclear Power Station resulted indirectly in the shutdown of most of the nuclear power plants in Japan. To compensate for the lost nuclear power supply, more fossil fuels were used. People became concerned that this could be disadvantageous for domestic manufacturing industries and accelerated their offshoring to Asia, especially China, through foreign direct investment (FDI). We used a world trade computable general equilibrium (CGE) model with endogenous FDI from Japan to China to quantify the impact of the power crisis on the Japanese manufacturing sectors. We found that the power crisis as well as FDI would adversely affect several sectors that use power intensively, but would benefit the transportation equipment (TEQ), electric equipment (EEQ) and machinery sectors, despite the common expectation that these sectors would undergo a so-called ‘hollowing-out.’ [ABSTRACT FROM PUBLISHER]

The history of the use of electricity in Japan began as telecommunication, which started in 1869, one year after the Meiji Restoration. The first electric arc lamp shone in Ginza, Tokyo, in 1882, the same year as the start of operation of Edison's Pearl Street Power Plant in New York. Only four years later (1886), Tokyo Electric Light Company, one of the predecessors of Tokyo Electric Power Company Holdings, started its business as the first electric power company in Japan. Many similar companies started their businesses in the following several years. In these early days, electric power companies in eastern Japan imported 50-Hz generators from Allgemeine Elektricitäts-Gesellschaft (AEG) in Germany, and those in western Japan imported 60-Hz generators from General Electric Company in the United States. From this historical background, AC 50 Hz is still used in eastern Japan and 60 Hz in western Japan. [ABSTRACT FROM AUTHOR]

Abstract: The JT-60SA satellite tokamak will be built in Naka, Japan. One of the main aims of this machine is to achieve steady-state high-beta plasmas. To reach this result, passive stabilizing plate (SP) and resistive wall modes (RWM) active control system based on 18 in-vessel coils will be installed. In the present design, these coils are placed on the plasma side of the SP, behind the first wall. This solution maximizes the efficiency in producing fast magnetic fields into the plasma by minimizing the shielding effect of the passive structures. Then, if the power supply (PS) and the control system have sufficient dynamic performance, it is possible to control the RWM with very low magnetic fields. This allows minimizing the Ampere-turns and the power requested to control the RWM. Conversely, the very fast dynamics required represents one of the main issues for the design of the RWM control system. This paper, after having recalled the main specification data for the RWM control system deriving from the physics studies, describes the analyses performed to complete the set of requirements necessary for the PS design. The characterization of coils and feeders is shown and the voltage necessary to produce the required current and bandwidth is quantified. Possible connections among PS and coils are analyzed in order to achieve the highest possible flexibility in controlling the RWM with a reduced set of independent PS. Finally, considerations on reasonable voltage margins to cope with load uncertainties are given. [Copyright &y& Elsevier]

The nuclear accident at the Fukushima Daiichi Nuclear Power Station (NPS), or the Fukushima Accident, was caused by the devastating tsunami associated with the Great East Japan Earthquake. It demonstrated that total station blackout and loss of core cooling and spent fuel pool cooling should be prevented at the time of natural disasters. At the same time, it became clear that a similar extensive nuclear accident could be caused by a terrorist attack on vital equipment that is essential for maintaining NPS power supply, core cooling, and spent fuel pool cooling. Thus the Advisory Committee on Nuclear Security (ACNS), established in December 2006 under the Atomic Energy Commission of Japan (JAEC), initiated the review of Fukushima Accident to extract lessons learned from nuclear security perspectives and made a report to JAEC in November 2011, summarizing the result of its review and recommending appropriate measures to overcome nuclear security vulnerabilities that have been identified by the Fukushima Accident. This paper presents the content of the ACNS report and the response of the relevant Japanese government agencies and licensees to its recommendations. [ABSTRACT FROM AUTHOR]

Abstract: In the framework of EU – JA “Broader Approach” Agreement, the JT-60SA satellite tokamak will be built in Naka, Japan. In JT-60SA, to achieve the steady-state high beta plasma, suppression of Resistive Wall Modes (RWM) is necessary. Therefore, a passive stabilizing plate and a RWM active control system based on in-vessel coils are foreseen for JT-60SA. In the present design, this system consists in 18 sector coils, 6 in the toroidal, 3 in the poloidal direction, rated for a maximum current of 2.5kA and fed by a dedicated fast power supply system. The coils shall produce sufficient radial magnetic field at the plasma edge, and the active control system shall be fast enough to react in real time to the plasma instabilities. In addition, during fast transients of the plasma current, significant loop voltage could be induced along the sector coils, which could result in over-currents in the coils and in the power supplies. This paper deals with the electromagnetic analyses on the sector coils of JT-60SA, with the main aim to determine the voltage/current characteristic of the coils and, at the same time, to have a first estimation of amplitude and shape of the produced magnetic field; different sector coil design solutions were considered and evaluated. The studies on the coil over-currents during plasma disruption or vertical displacement events are also presented. The results give useful indications in support to the development of the sector coils and power supply design and the identification of their electrical and functional requirements. [Copyright &y& Elsevier]

A CMOS ultra-wideband impulse radio (UWB-IR) transceiver was developed in 0.18-µm CMOS technology. It can be used for 1-Mb/s data communications as well as for precise range finding within an error of ±2.5 cm. The power consumptions of the transmitter and receiver for data communication are 0.7 and 4.0 mW, respectively. When an LNA operates intermittently through bias switching, the power consumption of the transceiver is only 1 mW. The range for data communication is 1 m with BER of 10-3. For ranging applications, the transmitter can reduce the power to 0.7 µW for 1k pulses per second, and the receiver consumes little power. The transceiver design, all-digital transmitter, and intermittent circuit operation at the receiver reduce the power consumption dramatically, which makes the transceiver well suited for applications like sensor networks. The electronic field intensity is lower than 35 µV/m, and thus the UWB system can be operated even under the current Japan radio regulations. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of windmills in relation to the design of multibladed windmill generator systems employed at the Notozima Family Trip Village in Japan. The maximum power coefficient of the windmill is 0.13. The maximum power coefficient can be obtained when the blade pitch angle lies in the range between 15 to 20 degrees. The starting torque coefficient of the windmill also increases as the blade pitch angle increases to 30 degrees.

Focuses on the increase in the power density of the electric system with the rapid growth of demand in Japan. Advantages of the strong interconnection of power system; Means of preventing the occurrence of fault cascading; Problems associated with power system expansion.

This paper empirically examines customer preferences for the reliable sources of electricity, using data obtained from a survey of back-up systems owned by large computer users in Japan. The empirical results based on probabilistic discrete choice models indicate that (1) customers face a trade-off between the price and the reliability of the power supply, and (2) customer characteristics, such as types of business and levels of electricity usage, have significant impacts on the choice of back-up apparatuses. The estimates of cost changes which would offset reliability changes imply that the financial and communications sectors are more concerned about reliability than are other sectors. [ABSTRACT FROM AUTHOR]

Describes the development goal and system configuration of the self-commutated alternating current/direct current (ac/dc) converter station assumed in a project conducted by power utilities and Central Research Institute of Electric Power Industry (CRIEPE) in Japan. Composition of a self-commutated ac/dc converter; Details on the first stage of the project; Details on the expected features; Verification test results of the prototype converter models.

The world's electric power system continues to be a principal source of carbon emissions, comparable to transport and such industries as steel and cement. Intense debate surrounds the issue of the pace at which it is greening. In this paper we offer a precise definition of greening as a rising proportion of electric power sourced from water, wind and sun (WWS), since these are all fundamentally renewable. Using the latest data from the BP Energy Review as well as national and regional sources, we demonstrate that by 2019 the EU-28 had reached a proportion of electricity generated from WWS of 34%, followed by China at 27%, Japan at 19% and the US at 17%. Moreover, the EU-28 achieved the fastest pace of transition, increasing its WWS-share of electricity generated from 20% in 2010 to 34% in 2019, or a 14% green shift in a decade. Over the same period, China's green shift in power generation was 10%, while that of Japan was 9% (all achieved in the decade following the Fukushima disaster) and the US at an 7% shift. The IEA has just issued a report revealing that globally renewable sources of energy account for 29% of electricity generated in 2020, up 2% on 2019 levels. [ABSTRACT FROM AUTHOR]

In Japan, approximately 70% of the primary energy supply is converted into low-temperature (lower than 200 °C) waste heat, which represents a small energy density; therefore, its utilization is limited to applications such as heat pumps, organic Rankine cycle, etc. In this paper, therefore, work from the heat source with a small difference in temperature is obtained using a gas hydrate power cycle. Furthermore, a new electric generator system is proposed. In the gas hydrate power cycle, gas hydrate is produced due to a low-temperature heat source (environment of a cold area), and then dissociated, resulting in high-pressure gas, due to a high-temperature heat source. In this cycle, the temperatures of the heat sources were set at −5 °C and 15 °C ; therefore, in the proposed system, cold environment and waste heat can be considered as the low and high temperature heat source, respectively. With this system, the dissociation efficiency of CO 2 hydrate when using a generation catalyst was at 42.5%, and the instant power conversion percentage of the actuator and generator was at 40.2%. Finally, 17.1% of the heat provided by the high-temperature heat source was converted into electric power by CO 2 hydrate power cycle. • A novel power generation system to use the energy of the wasted heat. • Power generation system uses the formation and dissociation process of the CO 2 hydrate. • The overall efficiency of 17% was obtained, which is higher than organic Rankine cycle. • Environmentally friendly generation system was proposed. [ABSTRACT FROM AUTHOR]

In order to reconstruct organ-absorbed dose from recorded dose for risk estimation in nuclear worker cohort, the preceding study of the International Agency for Research on Cancer (IARC) 15-Country Collaborative Study estimated the organ dose conversion factor from the recorded dose of H p(10) under the assumption that on average, in the nuclear power plants (NPPs), 10% of the dose received by workers was due to photon energies ranging from 100 to 300 keV and 90% from photon energies ranging from 300 to 3000 keV, with the average geometry being 50% in the antero-posterior geometry and 50% in the isotropic geometry. Similar examination was conducted at the Japanese Epidemiological Study on Low-Dose Radiation Effects (J-EPISODE). Literature survey disclosed that Japanese electric power companies had jointly conducted the research on energy distribution and incidence direction distribution of gamma rays in working environments during periodical inspection and maintenance as well as during operation in the 1980s. The analysis of the survey results on photon energy and geometry distribution of Japanese NPPs demonstrated appropriateness in applying the IARC study assumption for nuclear workers in Japan and reconstructing organ-absorbed dose in the J-EPISODE. These results in Japan also provide strong evidence to support the robustness and generality of the IARC study assumption, which was estimated based on the judgment of experts at nuclear facilities around the world. [ABSTRACT FROM AUTHOR]

In response to the Fukushima Daiichi Nuclear Power Plant's severe crisis, the Tokyo Electric Power Company planned rolling blackouts, and the Japanese government encouraged companies and residents to conserve electricity by adopting self‐restriction plans. We examine the structural changes caused by the disaster in Japan and the effects of the power blackouts and self‐restriction plans on the magnitude and pattern of load demand. The results show that the total demand decreased after the disaster and changed from weekdays to weekends and holidays. In addition, the effect of temperature on load demand changed after the disaster. [ABSTRACT FROM AUTHOR]

The article introduces the new generation superconducting coils and magnets developed by Fujikura Ltd., one of Japan's leading power cable and wire manufacturing companies. This is the second achievement of Japan in terms of superconductivity power. The first was issued last March and April. This new discovery can carry large current High-T superconductor wires. By using these wires, high performance electric power devices will have lower cooling cost.

SUMMARY It is desirable that the number of forward contracts traded on the Japan Electric Power Exchange increase. However, few studies have clarified what factors have contributed to impacting the number of forward contracts traded. In this study, the authors analyzed the number of forward contracts using four count regression models. The negative binomial regression model and the zero-inflated models were better able to express the expected counts, by incorporating the overdispersion and excess zeros present in the observed data. Among others, the spot market can carry positive influences on the expected counts, by about 12% for a 1 yen/kWh increase in price, and by about 27% for a 0.1%-point increase in volumes. The zero-inflated models revealed that as many as three-fourth of the entire forward products have a high probability of zero counts, while the remaining one-fourth may see an increased number of counts as the spot market price and/or the spot volume becomes higher. [ABSTRACT FROM AUTHOR]