2015 VOL.70 NO.1

  Special Reports

Hydroelectric Power Generation Creating New Value

Evolving Hydroelectric Power Generation
HAYASHI Masataka

Trends in Hydroelectric Power Generation and Toshiba's Approach
TODA Kazunori / MORI Junji
Hydroelectric power generation, which accounts for the largest share of renewable energy sources, is being reevaluated in terms of its role in maintaining stable power supplies by compensating for power fluctuations resulting from the increasing use of renewable energy sources such as wind and photovoltaic systems that are affected by weather conditions, in addition to its role as a baseload power supply. The ratio of hydroelectric power generation among all types of power generation facilities is expected to continue to increase globally in the future.
As a leading company in the hydroelectric power generation field, Toshiba is responding to these circumstances by further advancing related technologies and promoting the expansion of their application worldwide.

Commencement of Commercial Operation of Kazunogawa Hydroelectric Power Station Unit 4 of Tokyo Electric Power Co., Inc. Employing World's Largest Capacity Adjustable-Speed System
FUJITA Takashi / TOJO Hirotaka / KOYAMA Hajime
Unit 4 of the Kazunogawa Hydroelectric Power Station of Tokyo Electric Power Co., Inc., located in the cities of Otsuki in Yamanashi Prefecture, started commercial operation on June 9, 2014. Although construction work on Unit 4 was suspended in 2002, it was urgently restarted as a countermeasure against the shortage of electricity following the Great East Japan Earthquake.
Toshiba successfully completed the manufacturing of the equipment and construction work within the short period of about three years. Unit 4 is an adjustable-speed pumped-storage hydroelectric power system with the world's largest capacity employing a pump turbine with the world's highest pump head and an AC excitation system using an injection enhanced gate transistor (IEGT) inverter and converter. It is expected to contribute to the stabilization of electricity generation and the effective utilization of hydropower resources, while providing a large-capacity storage function equivalent to that of constant-speed systems.

Commencement of Commercial Operation of Kyogoku Hydroelectric Power Station Unit 1 of Hokkaido Electric Power Co., Inc. Equipped with Adjustable-Speed System
TANAKA Takehiro / SAKAMOTO Shigeru / SHIOZAKI Yuichi
Unit 1 of the Kyogoku Hydroelectric Power Station of Hokkaido Electric Power Co., Inc., located in the northeastern area at the base of Mt. Yoteizan about 35 km southwest of Sapporo City, entered commercial operation on October 1, 2014. This is the first solely pumped-storage type power plant (max. 600 MW, 200 MW × 3 units) applying an adjustable-speed system with peak-power supply capability and the ability to suppress fluctuations in frequency.
Toshiba put the world's first adjustable-speed pumped-storage hydropower system into practical use in 1990 for the effective utilization of water resources. We have now applied injection enhanced gate transistors (IEGTs) to power conversion equipment in the AC excitation system of an adjustable-speed system for the first time, resulting in reductions in dimensions and loss. We have also developed the structure of a pump-turbine that allows the guide vanes to be disassembled from the lower side, for easy inspection. The Kyogoku Hydroelectric Power Station is expected to contribute to the stability of the electric power grid in Hokkaido.

Approach to Large-Scale Refurbishment of Hydroelectric Power Plants in North America
In recent years, there has been a conspicuous increase in demand for electricity accompanying the economic growth in developing countries. In countries having an abundance of potential hydroelectric power, including China, other Asian countries, and countries in South America, a large number of projects for the new construction of hydroelectric power plants are in progress. In economically developed North America, on the other hand, where hydroelectric power generation still plays an important role, the refurbishment and replacement of existing equipment are mainly being planned rather than new construction.
Toshiba is vigorously promoting the large-scale refurbishment of existing hydroelectric power plants in North America, including hydroelectric power equipment manufactured by other companies, through activities based at the dedicated office of Toshiba International Corporation in Denver, Colorado.

Technologies for Small and Medium-Sized Hydroelectric Power Generation Systems to Effectively Use Limited Water Resources
TAMURA Yasushi / NAKAHARA Yusuke / MIYAZAKI Masahiro
In the field of small and medium-sized hydroelectric power generation systems in Japan, demand has been growing for the renewal and new construction of equipment not only for the hydroelectric power plants of electric power companies to improve their performance and increase power output, but also for those of independent power producers to enhance their cost effectiveness accompanying the introduction of the feed-in tariff (FIT) system.
In response to these market demands, Toshiba is actively engaged in the development and application of new technologies including an adjustable-speed control technology, as well as technologies to achieve the simplification of facilities and enhance the efficiency of plant operations such as electroactuation and air-cooled bearing technologies.

Technologies to Achieve Higher Performance and Modernization of Hydroelectric Power Generation Facilities
Hydroelectric power generation is expected to further expand worldwide as a power source that can provide large amounts of electricity with minimal increase in environmental burden.
Against this background, Toshiba has been continuously developing a wide variety of technologies to improve the performance and quality of turbines and generators, including a simulation technology to optimize turbine runner shape, thrust bearings with a plastic surface, a radial ventilation cooling system, and many others. We are making efforts to supply products with the world's highest level of performance by applying these technologies to the new construction and renewal of hydroelectric power plants in both the Japanese and overseas markets.

Ten Years of Progress at Toshiba Hydro Power (Hangzhou) Co., Ltd. and Approaches to Technical Development
MORI Junji / ZHENG Jueping / SONG Xiang
Toshiba Hydro Power (Hangzhou) Co., Ltd. (THPC), a base for the hydroelectric power generation business of Toshiba in the Chinese market, has celebrated its 10th anniversary of operation. Since its foundation in January 2005, THPC has been engaged in the development and expansion of its large-scale manufacturing factory and electric parts production factory, the establishment of research facilities including the Hydraulic Machine Research Laboratory and the Insulation Development Center, the introduction of a facility governance system equivalent to that in our Japanese facilities, and the nurturing of human resources, focusing on equipment for low-head and large-capacity hydroelectric power plants to meet the specific characteristics of the Chinese market. THPC has produced more than 100 units each of turbines and generators so far, and been making progress in further enhancing its technical capabilities.


  Feature Articles

Fast Magnetic Resonance Imaging Technology for Time-Series Image Diagnosis
TAKESHIMA Hidenori / SAITO Kanako / KUHARA Shigehide
To expand the range of applicability of magnetic resonance imaging (MRI) tests, the Toshiba Group is engaged in the development of a time-series imaging technology with the aim of achieving double the acquisition speed compared with the conventional parallel imaging (PI) method. Although the PI method, which is the principal method used in existing products, can provide acquired images with approximately two or three times the spatial and/or temporal resolution through the integration of multiple coils and image processing technologies, it is not sufficient for time-series image diagnosis. A time-series PI method to increase the acceleration factors of PI requires an additional time-series map scan for calibration, hindering the improvement of imaging speed.
In order to achieve a breakthrough in this situation, we are developing a fast MRI technology that can reconstruct images using the time-series PI method without the need for an additional time-series map scan. The resulting enhancement of the imaging speed will be useful in various areas, such as the acquisition of cardiac images with higher resolution.

Inter-Device Synchronous Control Technology for IoT Systems Using Wireless LAN Modules
TOHZAKA Yuji / SAKAMOTO Takafumi / DOI Yusuke
Accompanying the expansion of the Internet of Things (IoT), interconnections between multiple devices and their cooperative operation via wireless LAN modules have become essential to achieve more efficient functioning of IoT systems. Timing synchronization through wireless communication has therefore become an issue of vital importance for various IoT systems.
Toshiba has developed a wireless synchronous control system that can establish synchronization between multiple devices with a high degree of accuracy using existing wireless LAN modules. The timing signal for cooperative operations is provided by the wireless LAN module attached to each of the devices, in which all additional functions are implemented as software. Experiments on a system using wireless LAN modules that implement a set of algorithms to compensate for synchronization errors due to jitter caused by other tasks running on the CPU have confirmed that it achieves a synchronization accuracy within approximately ±200 µs even in the worst-case jitter scenario. It is expected that IoT systems incorporating this wireless synchronous control system will be able to be constructed at a cost equivalent to those employing a conventional wireless LAN system without any need for additional hardware.

Lifetime Evaluation Technologies for Rubber Materials
Various types of rubber materials are used in equipment for a broad range of applications with diverse requirements. However, it is difficult to select the optimal rubber material that attains the required performance for a particular application because the physical properties listed in the manufacturer's specifications and measured by the relevant test methods prescribed in the Japanese Industrial Standards (JIS), which are effective for delineating the initial characteristics of rubber materials, are not guaranteed in the long term. In particular, rubber materials with stable long-term seal performance are essential for equipment used in power transmission and transformation systems.
With this as a background, Toshiba has developed lifetime evaluation technologies for rubber materials focusing on seal performance degradation factors including temperature and oxygen concentration through life tests extending over tens of thousands of hours based on compression sets. We have applied these technologies to the evaluation of rubber materials affected by temperature variations and the selection of oxidation-resistant rubber materials. We are also conducting verification tests and have confirmed the effectiveness of these lifetime estimation technologies using compression sets even in the case of rubber materials installed in existing equipment.

HRE190 Spot Network Relay Contributing to More Stable Operation of Spot Network Receiving Facilities
Spot network relays, a type of digital relay specialized for spot network receiving facilities mainly deployed in urban areas, are contributing to the stability of electric power systems through the following automatic functions that constitute the three characteristics required for a spot network: a power-on function in the case of no voltage on the secondary side, a power-on function in the case of a voltage difference between the primary and secondary sides, and a reverse power interrupt function. Toshiba launched the world's first numerical protection relay in 1980, and subsequently developed digital relays for spot network systems in 1985. Since 1997, we have supplied a number of spot network systems equipped with DH1 spot network relays.
We have now developed the HRE190 spot network relay, a new numerical spot network relay product achieving greater compactness as well as improved reliability and usability by integrating multiple functions.

Application of Lead-Free Solder to Products to Achieve Low Cost and High Quality
SUGAI Takahiro / MIYAMOTO Toshiaki / ITAGAKI Tatsuya
SAC305 is a lead-free solder paste alloy formed from a composition of tin (Sn), silver (Ag), and copper (Cu), represented by Sn-3.0Ag-0.5Cu, that has been widely used to solder electronic parts on printed circuit boards (PCBs) for notebook PCs and TVs. In recent years, increases in solder material costs due to the rising price of Ag have become a factor in increasing product costs. Although solder alloy compositions such as Sn-1.0Ag-0.7Cu and Sn-0.3Ag-0.7Cu have been proposed to reduced costs, issues regarding the degradation of solder joint reliability and increase in the solder melting point have been pointed out in relation to these compositions.
As a solution to these issues, Toshiba has developed lead-free solder pastes that achieve low cost as well as high solder joint reliability and manufacturability by adding small amounts of specific elements while reducing the Ag content, and confirmed their effectiveness through the results of product evaluations. We have applied these lead-free solder pastes to our notebook PCs since 2014.

Conferencing Audio Utilization System Supporting Efficient Business Operations
TAKAHASHI Mariko / KONDO Nobuaki
The use of audio and video systems has been expanding in both the corporate and social infrastructure fields in recent years. In particular, the widespread dissemination of video conferencing systems and Web conferencing systems with image display functions has led to a growing need for business sites to make more effective use of the audio data produced by these systems.
To meet such customer requirements, Toshiba Solutions Corporation has developed a conferencing audio utilization system that realizes efficient use of recorded voice data by means of a PC. This system, incorporating a large-vocabulary speech recognition technology with high speech recognition accuracy developed by Toshiba, has the potential for application to various lectures and meetings. It supports daily business operations through a variety of functions, including a function that displays the contents of conversations to prevent missing words, a replay function to confirm conversations before and after important utterances, and functions to support the preparation of minutes of meetings and reviews by participants at past meetings.


  Frontiers of  Research & Development

Smart TV Alliance to Promote Standardization of Development Specifications for Smart TV Applications

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