We have been developing the superconducting magnetic separation system installed in the thermal power generation water supply system to remove the iron oxide scale and reduce carbon dioxide emission. The types of scales produced are different depending on the water treatment method, and an appropriate magnetic separation method is developing.

Design of balancing market is being carried out in Japan as one of the power system reforming. Because of the wide area trading of balancing capacity, there is the margin on the tie lines, and the margin has influence on the empty capacity of the tie lines. When the margin is large, economic efficiency may decrease due to limitation of wide-area energy trading. So, it is important to discuss how much margin should be secured. In this paper, wide-area trading of balancing capacity was simulated by three-step Unit Commitment (UC). The results were used to evaluate the economic effects on the entire region. In addition, the margin setting of tie lines between regions was investigated for three cases, and the effect on economic efficiency was evaluated. As a result, it was shown that the wide-area trading of balancing capacity improves the economic efficiency of the entire region. And it was also indicated that regarding the margin of the tie lines between regions, it is economically better to set different margin in time, rather than set fixed margin in all time, according to the transactions of electric power.

This paper proposes a novel design of a single-phase microgrid (SMG) by utilizing the conventional 100/200V distribution network. The single-phase synchronous inverter (SSI) using “non-interference core (NIC) dynamic model” previously proposed by the authors is improved for realizing stable operation of SMG. A newly developed controller using the Xd' generator model implemented as the SSI core dynamics show satisfactory performance for stable MG operation. This implies that the NIC model works successfully without causing any instability phenomena. The laboratory experiments using two 100V SSI hardware have shown the feasibility and effectiveness of the proposed SMG.

Transformers are normally energized from the higher voltage winding. In power system restoration, however, they may be energized from the lower voltage winding. Therefore, a reversible transformer model that is able to accurately calculate inrush currents and some other low-frequency transients is required regardless of which winding is energized. Although a reversible transformer model based on a topology-based model that considers magnetic couplings between phases has been proposed, it is difficult to determine the parameters of the model because iron-core and winding design information are not available in most cases. In addition, the approximation of the design information required when such information is not available does not always hold accurately. In this paper, a reversible transformer model that can be composed only from available information such as nameplates and test reports, without using the design information (or the approximation), by using mutually coupled magnetic resistances has been developed. As a result of verification using a 500VA single-phase three-winding transformer, it is indicated that the inrush currents calculated by the developed model are in good agreement with those obtained by the laboratory measurements using the test transformer regardless of which winding is energized.

We investigate the method of the branch point estimation using the common earthing conductor, when disconnection occurs at the trunk line and branch line of the distribution line with the branch line. The disconnection detection method using common earthing conductor estimates disconnection point from the time difference of the zero-crossing point of the current flowing at the rising of each common earthing conductor in connected the end point of two adjacent distribution lines. When the branch line of the distribution line is broken, the relationship between the time difference between the zero crossing points and the disconnection distance of the current caused by the wire returning to the feed point of the two common earthing lines is shown, and the cause of the time difference at the zero-crossing point is clarified. In addition, the operating conditions for application to actual equipment will be examined and the results will be shown.

This paper proposes a switching sequence for enabling continuous operation of power plants under DC line faults in the multi-circuit HVDC transmission system. The conventional switching method requires a shutdown and a restart of the power plant after the DC line faults, resulting in power outage for more than several minutes. The proposed switching method enables the continuous operation of the power plant and reduces the power outage after the DC line faults. Simulation results demonstrate that the proposed method reduces the power outage to 0.2 seconds.

Battery Energy Storage System (BESS) as an infrastructure system should operate stably for a long period of time. We are aiming for a system that uses robust components and replaces them after they have been used up to the end of their individual life. We have developed the Voltage Deviation Method (VD Method) to monitor soundness of In-service BESS using operation data. In this paper, we propose the improved method to detect partial degradation within a battery unit which couldn't be detected by the original VD Method, and describe results of State of Health (SoH) monitoring with detection of partial degradation of BESS in field operation.