This paper explained the basic concept of lightning protection design for wind power generation facilities common to onshore and offshore facilities, and described the points to be considered in offshore wind power. There is concern that the offshore WF sea area will become a hotspot for lightning, but it is difficult to accurately judge whether this is true or not at this time. The current blade sanity check process could pose a bigger problem for offshore WF from the view point of a risk management perspective. Regarding issues related to accessibility, it is important to develop technologies related to remote monitoring and automated driving and establish related laws so as not to significantly impair the business viability of offshore wind power generation.

Due to penetration of generators connected to power grid via Grid-Following inverters, transient stability of power system is deteriorated. In contrast, Grid-Forming inverters can provide virtual inertia and synchronizing power, and are expected to contribute to system stability. In this paper, the influence of GFM location in the power system and control parameters on transient stability is evaluated by RMS simulation. Then based on aforementioned analysis result, method to determine optimal location and control of GFM is proposed and verified using EAST10 model.

This paper proposes an efficient method for wind power generation output forecasting. The proposed method is based on Radial Basis Function Network (RBFN) of Artificial Neural Network (ANN). In this paper, a couple of strategies are proposed to improve the performance of RBFN. One is the use of the Wavelet Transform as the preconditioning technique while the other is to apply the idea of ELM (Extreme Learning Machine) to RBFN. The effectiveness of the proposed method is demonstrated for real data of wind power generation output.

For improving the profitability of electricity retailers, it is important to reduce the penalty cost for the imbalance between a day-ahead planned electricity demand and the actual electricity demand on the day. To reduce the imbalance, a Battery Energy Storage System (BESS) installed in customers of the electricity retailer can be used. Assuming that the forecast error of Photovoltaic (PV) power output forecast error can be major reason of the imbalance in retailer using a certain amount of its own PV, our previous study proposed the simple operation of BESS based on the prediction of the direction of forecast error (positive or negative) instead of the amount of error, and revealed that the proposed method can be useful if the available BESS capacity is smaller than the imbalance. Based on the results in previous study, this paper conducts the economic assessment of imbalance reduction by the proposed BESS operation by using the actual data on imbalance charges and electricity market prices for a year. Both the change in imbalance cost in daytime and the preparation cost of BESS in night-time for the next day operation are taken into account. Furthermore, the break-even point of the imbalance charges at which this BESS operation method can achieve relatively higher profitability is examined.

When constraints required for asset planning in distribution systems are violated by installing a new large load, distribution system reconfiguration becomes necessary to satisfy the constraints. However, due to the severe constraints caused by installing the new large load, it is not easy to find new distribution system candidates. If the reconfiguration does not satisfy the constraints, the investment in equipment such as upsizing distribution lines is required, which should be avoided as much as possible to minimize monetary costs. This paper proposes a multi-objective optimization-based approach to find new distribution system candidates to handle this intractable problem. We formulate the reconfiguration problem as a many-objective optimization problem with four minimization objectives: (i) the upper and lower bound violations of voltage, (ii) the upper bound violation of distribution line current, (iii) the bias in the number of automatic switch sections, and (iv) the number of exchanges between manual and remote switches. This problem is efficiently solved by a many-objective evolutionary algorithm that can provide both the distribution system candidates and information on the necessary upsizing lines to satisfy the constraints. The effectiveness of the proposed method is verified by computational experiments using a practical large-scale distribution system model.

Corrosion and breakages of shielding layers are one of the factors for degradation of extruded three-layer (E-E type) 6.6kV cross-linked polyethylene (XLPE) cables. Tohoku Electric Power Network has been measuring electrical resistances of shielding layers in E-E type 6.6kV XLPE cables, and recently has found breakages of shielding layers. The authors performed an accelerated degradation test for shielding layers of E-E type 6.6kV XLPE cables by taking account of aqueous solution, temperature, heat cycles, bending stress, frequency of an applied voltage, and water-proof layer in the test conditions, and investigated factors affecting corrosion and breakages of shielding layers. Corrosion, cracks, and breakages were found on shielding layers in the cables without water-proof layer, but no crack was found in the cables with water-proof layer, when heat cycles were applied to the cables, and shielding layers were supplied with artificial sea water. We investigated the suppressive effect of the cables with water-proof layer on cracks and breakages of shielding layers by measuring tensile strengths of copper tapes obtained from the shielding layers of the cables with and without water-proof layers.

The experiments of pre-ionized inert gas plasma MHD electrical power generation are conducted, and the performance and plasma behavior in the experimental generator are examined through time-dependent r-θ two-dimensional numerical simulation. In the experiment, an enthalpy extraction ratio of 4.01% has been obtained with a disk-shaped MHD generator with radio-frequency pre-ionization. In the numerical simulation, at an assumed inlet electron temperature around 5600K (inlet ionization degree 0.10× 10^-4)∼6600K (1.36× 10^-4), the plasma structure is similar to the non-uniform structure observed in the experiment. An enthalpy extraction ratio around 2∼5% matches well with that in the experiment. At a suitable inlet electron temperature of 7000K (3.15× 10^-4)∼8000K (1.79× 10^-3), although non-uniform plasma structure still occurs, a high enthalpy extraction ratio over 10% is expected.