A railway infrastructure equipment requires extremely high reliability. In railway electrical systems, equipment failures due to lightning can lead to transportation failures. Although we are investigating and taking countermeasures for accidents caused by lightning, lightning troubles have continued in recent years. Therefore, we established a committee in 2019 to clarify the causes of these lightning-related accidents. This paper describes lightning protection for railway electrical systems.

In this study, we aim to build a simulation tool to contribute to the construction of the management methods of the new power supply and demand that targets the region. In this paper, as the first step of the tool construction, we developed a model to estimate the electric power daily load curves for the specified housing group with several hundreds to thousands of households in a particular area. By using this model, users can estimate the power consumption of any region in Japan according to the characteristics of the region, such as climate and the number of households. In addition, the estimation accuracy of the tool was verified using the statistical power measurement data and improved the estimation accuracy of the tool. The average annual energy consumption per household calculated by the tool was 16% larger than that calculated by the GDBL, but the correlation coefficient between the two was high at 0.76, indicating regional differences caused by differences in the number of households.

In recent years, penetration of renewable energy such as wind power generation has been increasing as measures against the global environmental problems. However, the system stability can be deteriorated when many such power supplies are introduced into the power systems. When a network fault such as a three-line-to-ground fault occurs in the grid with wind farms introduced, wind farms near the fault may be disconnected from the grid due to the voltage sag and then the grid system can be unstable. Under such a background, this paper proposes a new method for enhancing power system stability which is based on a cooperative virtual synchronous generator control between Adjustable Speed Synchronous Condenser (ASSC) and LFC (Load Frequency Control) hydro power plant.

Lightning protection for a boat is important since damage to the boat by lightning may directly lead to the risk of crew's life. The surge current when the boat is struck by lightning and the countermeasure was considered based on the results of numerical analysis in this paper. There is a risk that onboard equipment on the boat is damaged by surge current, even if the boat is 1km away from the lightning strike point. The amplitude of the surge current on the boat depends on the direction and the distance of the lightning strike point from the boat. When some grounding electrodes or metal parts are lined up in the same direction as the surge current direction in the seawater, the surge current which invades to the boat is large. The electrode that is installed in parallel with the direction of the grounding electrodes as a countermeasure can reduce the surge current on the boat. However, if the electrodes as a countermeasure cannot be placed into the point close enough to grounding electrodes of the onboard equipment, it is safer to install the countermeasure on annular shape.

Renewable energy is attracting attention as an alternative to current mainstream power generator sources. One source of renewable energy is wave energy. We devised a simulator for the OWC-type wave power generator and developed a reciprocating airflow generator is generated reciprocating airflow by using the reciprocating motion of a piston. This piston motion was achieved by converting the rotational motion of the motor into linear motion of the ball screw via gears. Furthermore, we used a vertical axis turbine with arc camber blades and studied on the turbine characteristics. Owing to the reciprocation of the piston, a substantially sinusoidal reciprocating airflow was generated in the measurement section. It was confirmed that a reciprocating airflow speed was generated for all the target values. A load characteristic test of the turbine was conducted. It was confirmed that the maximum turbine output was 1.60W.