In warm regions, the high setup costs hinder the widespread installation of geothermal energy systems. To overcome this obstacle, we have developed the Geothermal air conditioning system using LBHE. It delivers 50% energy savings compared to air-cooled heat pumps and reduces installation expenses by 30% compared to traditional geothermal systems, even in warm climates. This paper examines its two main components: the Lining Borehole ground Heat Exchanger and the unified heat balance control.

Reverse power flow from a photovoltaic power generation system to distribution system is limited below a certain limit value. The behavior of a power conditioning system (PCS) for large capacity photovoltaic power generation system when the output power approached the output power limit value was experimentally estimated. Under the condition, the PCS became uncontrollable. It was pointed out that this phenomenon was caused by maximum power point tracking (MPPT) control of the PCS. Furthermore, some methods to avoid the uncontrollable condition of PCS were shown.

Multi-terminal HVDC (MTDC) system is considered as one of the promising configurations for offshore wind farms (WF) integration. This paper proposes a new emergency frequency control method for MTDC system, and then the effectiveness of the proposed method is confirmed through the simulation analysis for the six-terminal MTDC system.

Future massive introduction of renewable power generation can cause a large amount of surplus power. The surplus power can be utilized effectively to charge Electric Vehicles (EVs) significantly if the timing of charging demand can be shifted to follow the change in renewable power supply. In order to assess the feasible EV charging using surplus renewable power, this study proposes a model for EV users' charging decisions according to SOC and cumulative irradiance, in which individual EV utilization patterns are taken into account based on a road traffic census. Then, this study evaluates the effect of a Charging Promotion Time Zone (CPTZ) depending on the daily cumulative irradiance to increase EV charging by surplus power. The result for the Chubu area, which is in the middle of the main island in Japan, shows that the proposed CPTZ increases EV charging with renewable power by about 14% without compromising the convenience of EVs as vehicles.

As the renewable energy sources (RESs) integration expands, the capacity of the synchronous generators (SGs) connected to the power system decreases. The Load Frequency Sensitive Mode (LFSM) has been proposed to improve frequency stability for RES-dominated systems by the active power generation or consumption proportional to the measured frequency deviation. However, the potential impact of the LFSM on power systems, including the damping performance deterioration of wide-area power swing oscillations, is a raised concern. In this study, the effects of the LFSM on the wide-area power swing oscillations are analyzed in detail based on the simulation waveforms using the IEEJ WEST 10-machine system model. Furthermore, the improvement of LFSM-induced power swing deterioration was validated by adjusting parameters of the Δω-type Power System Stabilizer (PSS) embedded in the SGs to adapt to a wide frequency range. These findings provide valuable insights for grid operators, policymakers, and vendors with the challenges of ensuring a stable and reliable power system while accommodating the growing integration of RESs.

Under the condition of high penetration of PV system, large forecast error of solar irradiance can affect power supply and demand adjustment for example shortage of power supply and surplus power. Therefore, this study develops a model to foresee large forecast error of solar irradiance based on a variety of forecasted values of weather parameters such as low-level cloud cover caused by different combinations of physical schemes in a numerical weather prediction (NWP) model. Weather Research and Forecasting (WRF) is used as NWP model. The performance of the large forecast error foreseeing is evaluated by using Receiver Operating Characteristic (ROC) curves and False alarm rate (FAR) at Hit rate (HR) of 0.9. Target areas are Nagoya, Shizuoka, Nagano and Toyama. The results show that low-level cloud cover is useful for foreseeing of large forecast error of solar irradiance in summer at each area because of low false alarms with high hit rates. Furthermore, it is shown that useful weather parameters for foreseeing large forecast error of solar irradiance differ depending on areas and seasons, for example, in Nagano, Middle-level cloud cover is useful in seasons other than summer.

The general method for predicting radio noise in the AM radio frequency band near high-voltage transmission lines (HVTL) caused by corona discharges on the conductor surface of HVTL is to first predict the horizontal magnetic field and then multiply it by a conversion factor of 120π (=the wave impedance in free space) to obtain the vertical electric field. The same method is adapted in CISPR/TR18, the only document on corona noise near HVTL published by IEC. This paper examines the wave impedance near a single-phase HVTL with an infinitely long horizontal conductor at 15m above the ground through theoretical and numerical electromagnetic field analysis, and it is found that at the CISPR position and a frequency of 0.5MHz, as specified in TR18, the wave impedance is 148πΩ instead of 120πΩ. This represents a difference of about 2dB in the vertical electric field level.

The mission of the Research and Development (R&D) Steering Committee of the Power and Energy Society (PES) of the Institute of Electrical Engineers of Japan (IEEJ) is to facilitate the research and development in the electric power energy technology. In this article, activities of the R&D Steering Committee in fiscal year 2023 are reported. Also, recent trend and future issues are discussed. Furthermore, efforts and actions to invigorate technical activities of the IEEJ PES and to improve service for members are described.