Large-scale storage battery systems are expected to be deployed widely. In order to confirm the systems' conformities to relevant prospective standards, and conduct test related to the quality and the performance of large-scale storage battery systems, the facilities were designed and are under construction. Outline of the facilities and tests to be conducted is shown.

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In order to solve energy and environmental issues, the introduction of photovoltaics (PV) has been progressed in recent years. Due to the uncertain PV output fluctuation depending on the weather conditions, the proper frequency management becomes an important issue when a large amount of PVs are included in power systems. On the other hand, since the voltage increase in the end of feeder lines can be caused by the reverse power flow in distribution systems with PVs, it is needed to enhance the voltage controllability. When Gas Engine generators are included in distribution systems, they can contribute to both frequency and voltage control issues. However, the coordination between those control purposes will be another problem because the frequency and voltage controls have interactions each other. Hence, in this paper, we developed a distributed frequency control method taking into account the voltage constraint in distribution systems.

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Development of wind power generation resources is considered in Japan. However, long-distance transmission lines are necessary to utilize the wind power because most of the wind power resources are distant from load centers. A voltage source converter based high voltage dc transmission (VSC HVDC) system is an option to realize their effective use. A VSC HVDC system equipped with dc circuit breakers has been considered to clear the dc line faults promptly. However, the fault clearing characteristics by the dc circuit breakers have not been analyzed very well for the system with the long distance overhead transmission line.  This paper focuses on a fault clearing in the VSC HVDC system with long-distance overhead line by the dc circuit breaker using a new fault detection method. A 2.4-GW bipolar VSC HVDC system with 600km overhead transmission line is modeled and its operation performance is verified by computer simulations. The simulation results demonstrate the detailed fault clearing characteristics with the long transmission line. Moreover, specifications required for the dc circuit breakers are considered in terms of operation delay, peak current, and absorbed energy.

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Electromagnetic transient (EMT) simulations of relatively-large power systems have become quite common, for instance, in the case where simulations of HVDC converters are carried out with large AC power systems connected to the converters. Thus, the increase of computation time is a serious concern. To reduce computation time, this paper proposes a method to reduce computational demand of a remote power system which is located far from the source of a transient event to be simulated. In the proposed method, the remote power system which is supposed to be represented by a three-phase EMT-based model is reduced to a single-phase phasor-based model, and the size of the circuit to be simulated is thus reduced and the dynamics calculations of inductors and capacitors included in the remote power system are neglected. The calculation algorithm of generator models included in the remote power system is also simplified. The proposed method has been applied to EMT simulations of the WEST 10 benchmark power system prepared by the IEEJ, and it has been shown that the computation time is remarkably reduced without significant loss of accuracy if the portion assumed to be the remote power system is sufficiently far from the source of a transient event.

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Short-circuit tests for power circuit breakers and others require alternative short-time current measurement, from a few kA to over several tens kA. However, the reference measurement system as a national standard or a specified secondary standard instrument to directly perform comparative test as a complete calibration test in high current class has not yet been established globally. The Japan Short Circuit Testing Committee (hereinafter referred to as “JSTC”) has therefore developed a shunt resistor which can be used as a standard instrument for high current measurement. Reference system using this shunt resistor is also considered by JSTC. The performance of the newly developed shunt resistor has been checked through several methods, such as resistance measurement, high power current test, high frequency current test, temperature rise test and interference test. The results of the tests proved satisfactory performance. Resistance of the shunt resistor before and after the tests was invariant and stable. This makes the shunt resistor adequate for a reference in practical use. In addition, evaluation of uncertainty of the whole reference system including this shunt resistor satisfactorily fulfills the requirements of IEC 62475 edition 1.0, 2010.

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In recent years, in order to ensure the delightful walking space and improve the urban landscape, the type of shallowly buried underground system for the common duct system of power cables and other cables has been introduced in the Japanese power distribution system. When a short-circuit fault arc occurs on high-voltage power cables in an underground common duct, the pressure in the latter increases due to the high temperature of the arc and it is concerned that such a pressure rise will influence another electrical power equipment. Therefore, comprehending the pressure rise and propagation due to fault arcs by the short-circuit test is important. However, the pressure rise and propagation are affected by many factors. Therefore, simulation technology is effectively applied to examine such a pressure rise and propagation in addition to short-circuit tests. In this paper, a 3-D CFD calculation model was constructed regarding the pressure rise and propagation in the underground common duct and the numerical analysis was carried out. As a result, it was revealed that the simulation results corresponded with 20% accuracy to the maximum pressure rise obtained by short-circuit tests.

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R-θ two dimensional numerical simulations have been carried out to clarify the plasma behavior in a high-temperature inert gas plasma disk-shaped MHD generator. At low inlet total temperature and high load resistance, the plasma has spiral structure which is similar to the non-uniform structure under the weak noble gas ionization condition in a seed-plasma MHD generator. As seen in a linear-shaped faraday-type MHD generator, the plasma becomes stable with increase in the inlet total temperature because the coulomb collision of electrons becomes dominant. Even at low inlet total temperature, the ionization instability can be suppressed for low load resistance, because the relatively low electron temperature due to less Joule heating makes the ionization relaxation time longer than plasma residential time.

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