In Japan, installed capacity of variable renewable generation (VRG) is rapidly increasing. Through the efforts to make VRG into one of main power resource, vehicle-to-grid (V2G) is considered as an effective source of flexibility, which is concerned to lack under large amount of VRG. In this study, we analyze the cost reduction effect of using V2G as system flexibility through calculation of day-ahead unit commitment (UC) in Kyushu area. To consider uncertainty of day-ahead UC, we calculate UC simulation with operation reserve requirement considering day-ahead forecast error of photovoltaic (PV) generation, followed by economic dispatch (ED) simulation using actual PV generation. V2G as load frequency control (LFC) reduces operation cost especially when demand is low, even with 180,000EVs. Cost reduction per EV is about 20∼80JPY/day with 180,000EVs, which saturates if more EV participates in the control. V2G as operation reserve reduces discharge from EV for about 0.5∼1.5kWh/day/EV, which results in reducing degradation of EV battery.

Profitability of electric power producers is evaluated in this paper when the same secondary regulation market as Spanish one is introduced to Japan. When the power producers participate in the frequency regulation market, they must have the upward output margin for the frequency control, so that the power sale income is reduced while the revenue from the frequency regulation market is generated. These increased and decreased profits when participating in the frequency regulation market are formulated at first in this paper. Based on the formulation, the profitable situation where the power producers should participate in the frequency regulation market is clarified. Using Spanish market data statistics and actual data of JEPX spot market price, the profit of the power producers in the frequency regulation market is simulated. From those results, it is found that there is an economic merit of participating in the frequency regulation market at a specific JEPX spot market price.

As for the offshore windfarm connected multi-terminal high voltage direct current system, this paper proposes the new droop control scheme for onshore converters with active power limitation and dc voltage limitation, and then the simulation results with three terminal high voltage direct current system model are shown.

In recent years introduction of renewable energy (RE), such as photovoltaic (PV) power generation and wind power generation, has rapidly increased. Since output of the RE is affected by weather conditions, it will be difficult to keep supply and demand balance of power. So we focus on hydrogen-related technologies. And we have installed the Hydrogen production system. In this system there are two devices to suppress the fluctuation of PV output, electrolysis cell and battery. To evaluate contribution rate of those two devices, we propose a new method using phase of Fourier transform.

The installed capacity of photovoltaic (PV) systems has been increasing rapidly due to the enforcement of the feed-in tariff scheme in Japan. However, reverse power flows from the roof-mounted PV systems cause voltage-rises in distribution networks. As for the voltage stabilization with reactive power compensation, SVC (Static Var Compensator) has been installed in the high-voltage distribution network until now. On the other hand, reactive power compensation from the low-voltage side using demand side equipment is proposed as a promising alternative with its cost-effectiveness. This paper proposes a method for analyzing the cost-effectiveness of voltage stabilization under a combination of SVC and the demand side equipment. The proposed method reveals a cost-boundary-value of the demand side equipment where those are widely used, and analyze the changes in the cost-boundary-value under various power system conditions.

In this paper, a new method of water pumping scheduling in a water distribution system with providing balancing reserves to power systems is proposed. This method enables to obtain a daily schedule of pumping water and balancing reserves, which is based on prices of electric energy and balancing reserves, hourly water demand profile, and properties between water flow quantity and consumption electricity of water pumps. The proposed method consists of an optimization model which is formulated by Mixed Integer Linear Programming (MILP). The constraints about the fluctuation of the volume of water in a reservoir, which is occurred by providing the balancing reserves, is added into the proposed model. Adding these constraints, stable water distribution is enabled even when the balancing reserves are activated. To verify the validity of the proposed method, simulations of water pumping scheduling in some cases were done. As a result, net operational cost was decreased when water pumps provided the balancing reserves. Moreover, the operational feasibility of providing the balancing reserve from water pumps is clarified.

To estimate iron loss in interior permanent magnet (IPM) motors driven by PWM inverters accurately, 1-dimensional finite-element analyses for a silicon steel sheet in the thickness direction considering hysteretic property and skin effect were proposed. However, the method cannot directly consider so-called excess loss. To express the excess loss, the eddy current loss correction factor is introduced into the method and the basic property of the factor under sinusoidal excitation has been investigated. In this paper, we investigate the property of the factor for plastic deformation assumed for press working. Finally, we apply the iron loss estimation method to the IPM motors and discuss the contribution of eddy-current, hysteresis and excess losses.

In recent years, the expansion of high-voltage DC transmission system is expected, and DC interruption technology is regarded as important from the viewpoint of protection of the system. Especially, DC interruption technology using vacuum circuit breaker (VCB), which is environmentally friendly and safe, has attracted attention. In this paper, we focused on clarifying DC interruption conditions of VCB using high frequency current injection method, and conducted DC interruption test by changing circuit conditions. In addition, we modeled the DC interruption condition. Then, we evaluated the DC interruption performance with this model. Specifically, we introduced the index and probability processing. Finally, we obtained the interruption boundary of each electrode material at the first current zero point. In addition, we introduced the method for judging the interruption success or failure by comparing the random number and the interruption failure probability obtained by probability processing into the EMTP simulation. Then, we investigated the DC interruption characteristics in various circuit conditions on the EMTP.

In this research deep learning by fully connected neural networks is applied to predict power output of photovoltaic power generation in Hokkaido. A new prediction method is proposed. The effectiveness of the proposed method is shown by some examples.

The Editorial Committee is working in planning and editing of the publication of Power and Energy Society. In this article, activities of the committee of the last term are reported, and recent trend and future problems are also discussed. The process of planning and editing of the publication, and the challenges to reduce the necessary months for reviewing papers and to increase the number of submitted papers are shown.