Chugoku Electric Power (Japan)

Accurate electricity demand forecasting is essential for the efficient operation of energy management systems in regional microgrids. Various forecasting methods have been proposed, including statistical approaches, artificial intelligence (AI) techniques, and hybrid models that combine both. In our previous work, we developed a forecasting method based on Bayesian inference that achieves high prediction accuracy, ensures explainability, enables real-time processing, and allows for the quantification of uncertainty. By incorporating distinct demand patterns between weekdays and holidays, and applying Bayesian inference to historical data collected during the same time period on various past days, the method provides valuable insights for system operators. In this study, we further improve forecasting performance by introducing a hybrid approach that integrates the Bayesian method with other predictive models. A case study using actual demand data demonstrates that the proposed hybrid method statistically outperforms conventional models in key performance metrics, validating its effectiveness and practical applicability.

For lightning protection of medium voltage (MV) distribution lines in Japan, zinc oxide surge arresters (SAs), which suppress lightning overvoltages, are generally used. These SAs require grounding electrode with low resistance dedicated to them, and distribution operators are struggling to obtain and maintain low resistance especially in areas with severe soil conditions. In recent years, externally gapped line arresters (EGLAs), which do not require grounding, are expected to be introduced. This study evaluates the cost– performance ratio of SAs and EGLAs under varying installation intervals and numbers of protected phases. First, the flashover characteristics of EGLAs were obtained by an experiment. Next, lightning protection rates for SAs and EGLAs were calculated using electromagnetic transient analysis. The total cost of installation required by each element was calculated, and the lightning protection rate and total cost were comprehensively compared. The calculation results showed that installing EGLAs every 100 m in two phases offers high lightning protection rates and low cost for the studied distribution lines. The findings support more cost-effective lightning protection design for MV distribution lines.

In advanced hydrogen-fueled gas turbines, incomplete combustion of hydrogen creates a reducing environment, which introduces additional potential failure modes for existing thermal barrier coatings (TBCs). Therefore, this study investigated the discrepancies in failure modes of air plasma-sprayed yttria-stabilized zirconia (YSZ) coatings after heat treatment at 1100 °C in reducing (Ar + 5% H 2 ) and oxidizing (air) environments. Isothermal exposure in an oxidizing environment for 500 h caused a high degree of sintering of the YSZ top coat, and the hardness and Young’s modulus increased by 54.41% and 61.96%, respectively. Conversely, in a reducing environment, sintering of the top coat was inhibited, and the hardness and Young’s modulus only increased by 13.69% and 37.01%, respectively. In contrast to the stiffening-induced failure observed in the oxidizing environment, the weak intergranular and intersplat bonding were considered to be the main factors that reduced the toughness in the reducing environment. Moreover, Raman spectra confirmed that no phase transformations occurred in either environment. Therefore, this study showed that a reducing environment changed the potential failure modes of a YSZ coating, which provides insight into the long-term degradation behavior of TBCs in hydrogen-fueled gas turbines.

Environmental11fly ash (FA), concrete sludge cake (CSC), X-ray fluorescence (XRF), scanning electron microscope (SEM). concerns have spurred research into replacing thermal power with microwaves in chemical plants to promote sustainability. However, there is a lack of established methodologies for scaling up microwave heating furnaces through analytical and experimental approaches. In this study, a sintered material intended for use as roadbed material was developed using concrete sludge cake and fly ash from a thermal power plant. This material can incorporate up to 10 % carbon with the addition of certain additives. Furthermore, a microwave heating furnace was designed based on parametric analysis to ensure both homogeneity and efficiency in operation. The developed microwave furnace, with a capacity of 30 kW, is capable of sintering 640 kg of fly ash daily in a uniform manner. Employing the methodology outlined, microwave furnaces can be optimised to accommodate specific materials, facilitating the design of systems suitable for the electrification of chemical plants.

Renewable energy sources, such as wind turbine (WT) generators and photovoltaic (PV) systems with high uncertainties, are installed in the microgrid (MG) system, which affects its frequency stability. This paper proposes an adaptive model predictive control (AMPC)-based frequency controller to address the frequency stability of the MG. In this paper, an unscented Kalman filter (UKF) is applied to AMPC to update the prediction model’s parameters in real-time to realize high estimation accuracy. A modified islanded IEEE CIGRE benchmark MG system model is used to verify the effectiveness of the proposed method. The simulation results show that the proposed method can efficiently decrease the MG frequency problems with a better performance compared with the proportional-integral (PI) controller.

Abstract The ammonia combustion test was conducted at the selected test site, and it was confirmed that the ammonia used as fuel burned completely and that there was no impact on the existing plant due to the combustion. The NOx value did not differ significantly from that of coal burning, and the test was conducted without any problems within the environmental standard values. The study confirms that ammonia can contribute to power generation as a fuel without significant impact on the environment.KeywordsCo-firingCoal power plantAmmonia fuelNOx control

While sawing logs along the pith to produce lumber, warps would occur in lumber due to the release of residual stress. Correction sawing should be performed to correct warps, so warps decrease the yield of lumber. Therefore, it is crucial to find a way to produce straight lumber without correction sawing. The present study focused on a series of high temperature drying with load, and it was confirmed that residual stress was eliminated, and warp was corrected after a series of high temperature drying with load. Besides, the optimal schedule conditions of high temperature drying were determined. After 6 months of storage, the treated lumber remained straight and residual stress in lumber did not recover. By applying high temperature drying with load to warped lumber, it is possible to dry lumber and correct the warps at the same time.