Providing One-Stop Solutions for Renewable Energy Transmission

Shuji Mayama

Design Methods of Power Cable Transmission Systems for Large-Scale Installation of Renewable Energy

Shuji Mayama,
Chief Engineer, Power Cable Project Engineering Division

This paper presents the AC underground transmission cables that connect renewable energy generation sites to the existing power systems of a transmission system operator, and the technical challenges and solutions that arise along with the operation. I also report on system design techniques and optimization analysis for DC submarine transmission cables, which are expected to provide a means of delivering large amounts of electric power directly from the generation site to the point of demand.

In recent years, alternative power generation facilities using wind, solar, and other sources have increased. However, this increase does not necessarily mean that the use of renewable energy will advance on its own. What is important is to consider how to efficiently deliver the generated electricity to the demand areas.

How Sumitomo Electric Group's integrated strength and design excellence led to the solution of the problem

The cables and substation equipment that send renewable energy from the generation site to a power company are basically the same as those used for normal power transmission. The critical factor, however, is the combination of these elements, involving a careful analysis of the electrical matching between the power company's existing facilities and the power plant's new facilities, as well as an integrated design of cables, substation equipment, AC phase modifiers, and other equipment. The key is the capability to comprehensively execute the project to manufacture and install all of these components in an integrated and reliable manner.

In the power generation project at the Wind Farm Tsugaru in Aomori Prefecture, which was completed in 2019, Nissin Electric and Sumitomo Electric worked together to provide these solutions as a single integrated package, which received high evaluation. We also collaborated with Sumitomo Densetsu to design the power cable transmission route. The provision of such integrated solutions is one of our greatest strengths and other companies cannot easily compete with this.
  ​  wind power generation  

Our proprietary system design and route optimization analysis to advance Japan's wide-area grid building

Currently, Japan's power grid is unable to accommodate the rapid spread of renewable energy, therefore limiting the amount of electricity it receives and causing congestion in power transmission.

Japan’s renewable energy power generation potential is said to be several tens of gigawatts (GW). If wide-area interconnections incorporating DC submarine power transmission like those in Europe and the US are realized on a large scale, we will come closer to achieving carbon neutrality.

Since the Great East Japan Earthquake in 2011, I have persistently appealed to parties in various fields about the importance of DC submarine power transmission, anticipating the expanded introduction of renewable energy in Japan. However, a major problem remained: without organized submarine information, power companies could not draw up submarine power transmission plans, and without such plans, we could not formulate definite cable designs or construction plans. I kept looking for a way to break through this issue.

Amidst this, I came across the fundamental research on route optimization algorithms by Professor Shunpei Baba of the University of Tokyo in the NEDO Next Generation DC Power Transmission System Development Project, which I participated in 2015. By combining the research of the University of Tokyo with our technology, we have completed software that can automatically calculate the most suitable route for laying cables at minimal cost.

Laying submarine cables involves not only water depth and submarine geology, but also social factors such as fisheries. The software enables automatic calculation of the optimal route for cable installation by creating a multilayered database of a vast amount of marine information based on a developed algorithm. We have been receiving feedback from various sectors and are thrilled to be able to help this country plan a large-scale grid utilizing submarine power transmission.

  Shuji Mayama  

My mission to solve social issues

Since I joined the company, I have experienced a number of major transfers to different business sectors, from research laboratories to underground cable construction sites, to automotive wire harness business, to overseas submarine cable projects, each time forced to rebuild my skills and personal networks from scratch. At each new field, I had to find ways to make myself valuable to the company and society, and always tried to come up with new solutions and technologies. It may seem like a long way round, but looking back, I realize that each of the skills I acquired during these discontinuous transfers is connected to and utilized in my current research and development. My professional life as an engineer can be linked to the calculation of the optimum route for submarine cables, as I have always been seeking the shortest route to provide what society needs, looking 10 years ahead. It is a great honor for an engineer to know that the time has come for their accumulated technology to be useful to society. While our core business is electric wires and cables, we also have great potential in new fields such as sensors, power supply systems, batteries, and energy management. It is of great importance for society and for the development of our business that we formulate a new energy business that integrates all of these elements as our strength. It will take time, but with my life as a strategist, I will tackle this theme as my last mission.

Related links

・[Press release] Sumitomo Electric Completes the Construction of Japan's Largest Wind Farm "Wind Farm Tsugaru"

・[Products] High-voltage cables

・[Projects id] Challenge to Spread the Use of Renewable Energy

・[CSR] CSR Report 2020

・"Total System Development on Innovative and Large Scaled HVDC Cable System towards Expanded Installation of Large Offshore Wind Farms," CIGRE 2020


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