This paper introduces the practices toward energy conservation on commercial kitchens that install electric cooking appliances. The ventilation guideline (JEHC 103-2017) for commercial kitchens that install electric cooking appliances was established in 2017 based on more than 1,000 data concerned about capture and containment of exhaust hoods. The ventilation guideline contributes to reduce usually 20~30% of energy consumption.

If excess generation caused by increasing of photovoltaic and wind power generation plants is foreseen in a power system, the generation outputs of those plants are curtailed as a last resort in order to maintain the integrity of the power system. This paper proposes how the problem of minimizing curtailed excess wind power and allocating it fairly to all wind power generators can be formulated and solved with a linear programming method. Especially, necessary conditions for the minimum and fair allocation are identified mathematically. The validity of the LP based method has been checked with numerical computation of a simplified power system model.

This paper presents a novel method for monitoring and control of voltage stability of electric power systems. The proposed method is useful for analyzing the voltage profiles under various operating conditions until maximum loadings are reached. A continuation power flow method with predictor and corrector scheme is used to deal with the singularity of the power flow Jacobian, which successfully describe PV curves. The paper also proposes a novel method for optimal voltage regulations using voltage control devices of generators, on-load tap changers, shunt capacitors and reactors. An optimization problem is formulated as MILP problem where the objective is to minimize the control operations subject to operation constraints. Novelty line in the proposed formulation that takes account of possible situations of infeasibility of the control problem, where feasible region disappears and then voltages cannot be regulated within the specified upper and lower bounds. Even in such cases, the proposed formulation works successfully to minimize the total voltage violations exceeding their bounds. It is demonstrated that the proposed method provides successfully the voltage profiles with PV curves as well as the optimal control of the voltage control devices.

It is desirable to operate power equipment such as transformers considering improvement of utilization rate and the lifetime. It is considered that the application of dynamic rating to improve the utilization rate. However, the equipment is increasingly used with high load due to the dynamic rating, so it is necessary to understand the lifetime of the equipment and operate it. In order to implement the current capacity calculation formula and the average degree of polymerization calculation formula using for transformer lifetime estimation, it is required dedicated devices to perform complicated calculations for each formula. Therefore, this paper considers creating formulas with only four arithmetic operations for the current capacity calculation formula and the average degree of polymerization calculation formula, and implementing them in the same device. Also, it is required overload protection relay to perform dynamic rating, in order to prevent equipment failure. So, this paper shows the implementation of three functions, dynamic rating, overload protection function, and the average degree of polymerization calculation formula, for one IED that can perform simple calculations.

This paper shows the simulation of Short Line Fault (SLF) interrupting performances for CO₂-O₂ gas model circuit breakers. Interrupting performances of L90 condition were measured. To simulate the SLF interrupting performances for the CO₂-O₂ gas circuit breakers, serially connected 3 arc models were adopted. From the arc voltage measurements at L90 condition, the arc parameters of the arc model were estimated. As a result, it was good agreement with the measurements and simulations. The arc parameters of the CO₂-O₂ arc model were nearly equal to the CO₂. From the simulations using the arc model, it proved that most severe SLF condition for the CO₂-O₂ gas circuit breaker was from L80 to L73. It was able to show that the most severe SLF condition was decided by the energy balance of the post arc resistance.

Three-dimensional large scale magnetohydrodynamic, two-phase flow, and electrochemical reaction coupling numerical simulations of alkaline water electrolysis with magnetic field were conducted to elucidate the bubble-bubble interaction and the influence of that on the overpotential. Numerical results shown that the magnetic field enhances the coalesce of bubbles and the bubble size was increased with the increase in the magnetic flux density. Moreover, the magnetic field suppressed the cell overpotential by suppressing the anode overpotential and ohmic overpotential. This is because, KOH concentration around the anode is increased by mixing of the electrolyte, and the reduction of the shielding effect by coalescing of the bubbles.