Global energy trends have continued to change rapidly in recent years to keep pace with the goal of achieving carbon neutrality by 2050. On the other hand, power consumption demands have grown along with digitalization due to increasing use of artificial intelligence (AI) and high-capacity data centers. This has resulted in growing attention on hydroelectric power generation, the most widely used renewable energy source for ensuring a stable supply of power, leading to a further increase in hydroelectric power plants in many countries. Pumped-storage power generation, which can store energy and adjust power fluctuations, has become ever more important to realizing a sustainable society.

Toshiba Energy Systems & Solutions Corporation is committed to developing and delivering hydroelectric power generation systems that contribute to providing major power sources, stabilizing electric power systems via the Internet of Things (IoT) and optimization technologies, and to improving hydraulic turbine and generator performance and functionality by making full use of digital and AI technologies.

NAKASHIMA Takahiro / KAWAJIRI Hideyuki / NAKAMURA Takanori

Hydroelectric power generation is a renewable energy source that delivers a stable supply of power. Recent trends in more sophisticated hydraulic turbine performance underscore the need for technologies that facilitate the development of hydraulic turbines with optimal performance in a short period of time.

Toshiba Energy Systems & Solutions Corporation has developed technology that swiftly and precisely predicts hydraulic turbine performance using artificial intelligence (AI) as an alternative to computational fluid dynamics (CFD) analysis. Applying it to turbine runner and draft tube design confirms that turbine runner performance prediction errors using deep neural networks (DNNs) are within 15% of CFD results. Quick draft tube performance predictions are available using machine learning-based surrogate models instead of CFD while maintaining the same prediction accuracy. We have also confirmed that coupled analysis using a tool known as 1DCAE, in which the turbine runner and draft tube are modeled by CFD and other piping systems are modeled in a simple manner, delivers precise evaluations of flow-induced vibrations that impede the stable operation of hydraulic turbines.

HASUNUMA Takaaki / NAKAGAWA Naritoshi / GOTO Motoi

In the field of hydroelectric power generation, the manufacturing of hydraulic turbine equipment using repetitive processes continues to be conducted by skilled craftsmen. To address recent labor shortages, demand for technologies that balance high quality, and high efficiency continues to grow to overcome dependence on skilled craftsmen.

Toshiba Energy Systems & Solutions Corporation has developed the following technologies to streamline manufacturing of high-quality hydraulic turbine equipment utilizing three-dimensional (3D) data: (1) high-precision numerically controlled (NC) flange surface processing using 3D shape data in consideration of on-site installation welding deformations, (2) automatically controlled thermal spraying processes for confined turbine runner spaces based on optimal thermal spraying conditions obtained via 3D simulation technologies, and (3) visualization of deviations between designed and fabricated turbine runner welded shape parts using 3D measurement data to eliminate dependence on manual measurements. We are continuously working to further improve hydraulic turbine equipment manufacturing processes by verifying the effectiveness and practical application of these technologies.

KANEDA Hironari / TOSHIMITSU Tomoyoshi / KASHIWAGI Kohei

Adjustable-speed pumped-storage hydropower systems, which can store electricity and adjust electric power system fluctuations, have become increasingly important due to ongoing changes in Japanese electricity markets triggered by the expansion of renewable energy systems necessary for adjusting output power fluctuations.

Toshiba Energy Systems & Solutions Corporation completed the replacement of the adjustable-speed pumped-storage system for Unit 2 at the Electric Power Development Co., Ltd. Okukiyotsu No. 2 Power Station in October 2023. The new secondary excitation device power converter reduces power loss by about 26%, volume by about 37%, and shortens the startup time. The new system helps adjust the electricity supply and demand balance in electric power systems by flexibly operating in accordance with combined power sources.

ASANO Takeyoshi / ISHIZAKA Tomonari / SUZUKI Hiromichi

Smart grids currently face issues related to the global environment, and implementation of measures to ensure a stable power supply. These circumstances are seriously impacting electric power systems, resulting in a pressing need to act. The IEC (International Electrotechnical Commission) 61850 "Communication networks and systems for power utility automation" series standard series are now being applied to power stations, following substations where they are already in effect.

Toshiba Energy Systems & Solutions Corporation has developed an intelligent electronic device (IED) incorporating communication functions compliant with the IEC 61850 standard series used in monitoring and control systems for hydraulic turbine generators. The IED has been adopted to establish a monitoring and control network in compliance with the standards for a Kansai Electric Power Co., Inc. hydroelectric power plant.

YAMAGAMI Shunsuke / URAYOSHI Daiki / UEDA Koji

In April 2021, the Ministry of Economy, Trade and Industry (METI) of Japan formulated the "Smart Safety Action Plan for Electrical Safety" to deal with critical issues in operation and maintenance (O&M) of energy-related electrical equipment, such as deteriorating facilities and labor shortages due to an aging population. This action plan proposes to make effective use of smart technologies as measures against long working hours and heavy workloads that hydroelectric power plant O&M located in remote areas entail.

To help resolve this, Toshiba Energy Systems & Solutions Corporation is working on developing O&M support services for hydroelectric power plants driven by TOSHIBA SPINEX for Energy services, which is specialized in energy-related fields. We have established a remote monitoring system and developed edge devices to collect data inside and outside power plants, a patrol inspection system using digital terminals, and autonomous patrol inspection drones capable of imaging inspection targets across a wide area, including meters and water or oil leakage locations, while traveling along a predetermined patrol route through narrow passages and stairs.

TAKAHASHI Tomoaki / HIROSE Akihiko / KAWABATA Shunichi

With the introduction of renewable energy systems following recent trends in carbon neutrality initiatives, hydroelectric power generation is playing an important role in maintaining the balance of electricity demand in addition to ensuring a stable electricity supply. This has resulted in greater demand for enhanced hydro generator operational efficiency.

Toshiba Energy Systems & Solutions Corporation has responded by developing technologies that shorten the suspension of hydro generator operations in the event of failure or during inspection and repair works. We have developed an online monitoring system to monitor partial discharge (PD) in the stator coil, which is a precursor to insulation deterioration, by using new non-contact PD sensors which facilitate installation on existing hydro generators currently in operation. We have also developed inspection robots to perform internal inspections of hydro generators, as well as repair robots to fix wedge defects detected by hammering tests. These technologies are expected to help minimize the risk of unscheduled outages as well as the time required for inspection and repair work, thereby enhancing hydro generator operational efficiency.

HYUGA Takeshi / FUKUMA Junya / WU Jinshui

Since Toshiba Hydro Power (Hangzhou) Co., Ltd. (THPC), a base in China for the Toshiba Group hydroelectric power generation business, was established in January 2005, it has continuously worked to strengthen manufacturing capabilities by introducing the latest manufacturing equipment, to improve design and manufacturing technologies by promoting technological developments, as well as supplying various products to many countries and regions including China and Japan.

With the factory relocation completed in November 2024, THPC rearranged their layout and introduced the latest information technology (IT) as part of enhancing productivity. They have also taken into consideration manufacturing capacity and the optimal timing for relocating machine tools to ensure on-time product delivery.

Feature Articles

SHIMOKAWA Naoto

The Taiwan High Speed Rail, which is the first overseas deployment of Japanese high-speed rail technologies based on Shinkansen train systems, has been in operation for more than 15 years, necessitating the replacement or renovation of power supply facilities due to aging electronic components.

Toshiba Infrastructure Systems & Solutions Corporation is actively engaged in replacing control and relay panels (CRPs) at 30 power supply posts with new CRPs. To conduct CRP verification tests at installation sites without affecting commercial operations, we have established a procedure to facilitate the switch from existing CRPs to new CRPs by introducing a changeover panel. We have also developed a front-end processor (FEP) to control the power supply facility on a single monitoring screen in the event that existing and new transmission systems connecting the operation control center (OCC) and power supply posts are used concurrently. These technologies allowed us to complete the replacement of CRPs at three power supply posts by July 2024.

KIMOTO Shinichi / IIJIMA Ryosuke

Silicon carbide (SiC) trench-gate type metal-oxide-semiconductor field-effect transistors (MOSFETs) feature a gate electrode embedded in the trench of SiC surface and are expected to contribute on-resistance reduction via miniaturized cell structures. However, miniaturization progress is hindered by issues such as increasingly difficult manufacturing processes and decreasing device threshold voltage.

To resolve these issues, Toshiba Corporation has devised a novel cell structure to enable further miniaturization and a self-aligned process necessary for the cell structure formation. Estimations using prototypes with a cell pitch of up to 1.5 µm and channel length of up to 0.28 µm have confirmed that the specific on-resistance (R_onA) of 650 V-class SiC trench-gate type MOSFETs can be reduced to 0.72 mΩcm².

KANO Hiroya / OHNO Hiroshi / OKANO Hideaki / OHNO Akifumi

To improve productivity in the manufacturing industry, demand has grown in recent years for optical imaging technologies that can automatically detect the microdefects on curved surfaces of products via nondestructive inspection. However, visual inspection work often must be carried out by a limited number of skilled engineers because it is difficult for conventional optical imaging technologies to detect microdefects on curved surfaces.

The Toshiba Group has developed the following two technologies as a solution: (1) an optical system using both a stripe-patterned multicolor filter and radially diffusing illumination light, which can capture microdefects on curved surfaces as drastic color changes in the image, and (2) an image processing technique to automatically detect the microdefects by extracting drastic color changes through spatial differential processing. The results of tests applying these technologies to an automotive part with curved surfaces confirmed that the new optical imaging technologies can automatically detect the microdefects with a depth of several tens of micrometers on curved surfaces.

Frontiers of Research & Development

Method to Clarify Causes of Accidents during Collaborative Operation between Different Systems through Effective Utilization of Design Modeling

*Company, product, and service names appearing in each paper include those that are trademarks or registered trademarks of their respective companies.

Vol. 80, No. 1, January 2025

Index