Various practical problems including power system problems have been solved using least squares methods as basic techniques. However, the methods cannot be applied when outliers exist in data or errors are not normally distributed. In order to tackle the challenge, various methods have been developed. Recently, maximum correntropy criterion (MCC) has been proposed in the signal processing field and it has been verified to be effectively applicable to various problems including power system problems. This paper briefly overviews the MCC and summarizes MCC applications to power system problems. Applications to distribution system state estimation and connection phase estimation of pole mounted distribution transformers are shown as examples.

The Japanese government aims to achieve carbon neutrality by 2050 and transition to renewable energy sources.

However, traditional methods for restoring the power system after blackouts may not be suitable for future renewable energy-based systems. This study proposes a novel system restoration method based on inverter based power resources in an islanded distributed microgrid. The study focuses on the self-synchronization of inverter based power resources and employs a simulation approach using the VOC (Virtual Oscillator Control) based grid-forming inverter. Results show that the proposed method can provide an effective and efficient approach for system restoration in distributed microgrids. This activity highlights the potential of the proposed method in enabling a smooth transition towards a renewable energy-based power system.

In power systems, market mechanisms exist to match supply and demand in an economically rational way. However, supply and reserve shortages can occur in situations where the spot and reserve markets coexist. This paper proposes an electricity market model that considers the interaction of the two markets to analyze the impact of market trading on the reliability of operation of the power system. In this model, the decision-making of the reserve provider, who can bid in both markets, is modeled as an optimization problem based on the principle of profit maximization. Market clearing is represented as an optimization problem based on the principle of social surplus maximization. Using the proposed market model, the following phenomena will be analyzed: (1) the output allocation between generation power and reserve determined by the reserve providers base on bidding prices in each market; (2) the impact of the decision-making mechanism on the procurement of supply and reserve power; (3) the influence of the bidding prices in the both markets on the supply and reserve power. Numerical examples demonstrate that certain combinations of prices in the two markets lead to supply and reserve power shortages.

The Battery Energy Storage Systems are compatible with renewable energy, so they are becoming increasingly popular around the world. On the other hand, the number of fire accidents is increasing with the spread of batteries, and as a result of the author own analysis of these fire accidents, the author found phenomena unique to storage battery system fires. Therefore, the author will investigate whether domestic laws and regulations are compatible with these unique phenomena and propose necessary countermeasures.

Breakage of shielding layers is one of the factors for degradation of extruded three-layer (E-E type) 6.6kV cross-linked polyethylene (XLPE) cables. When a shielding layer breaks, where a charging current flows through an outer semiconducting layer, it is possible that a potential difference would arise at the gap of the shielding layer and temperature of the outer semiconducting layer increases, which may result in a fire accident of the cable. To investigate its mechanism, we applied an AC voltage as the potential difference to the gap between copper tapes which simulated a breakage of a shielding layer of an E-E type 6.6kV XLPE cable, and measured a current flowing through an outer semiconducting layer and temperature between the gap until the outer semiconducting layer caught fire. As a result, it was found that the temperature of the outer semiconducting layer between the gap exceeded 150^°C immediately after the voltage application, and increased up to 250^°C and higher just before the fire damage occurred. This result suggests that the temperature reached the ignition point of the outer semiconducting layer.