Tokyo Power Quake-proofs Its Grid Control System

Backup facility is designed to withstand extreme jolts

For a land regularly pummeled by typhoons and shaken by earthquakes, not to mention its several active volcanoes, Japan suffers remarkably few electric power disruptions of any duration. In the 10-year period between 1992 and 2001, customers of Japan's largest power supplier, Tokyo Electric Power Co. (Tepco), suffered an average power outage of less than 5 minutes in any given year.

By comparison, customers of 65 power utilities across 24 states in the United States had sustained power interruptions totaling 107 minutes on average in any one year during the same period, according to the nonprofit Electric Power Research Institute, based in Palo Alto, Calif.

Tepco revealed how it keeps outage durations down to an enviable few minutes for its 27 million customers when for the first time it allowed foreign journalists to view its operations and the company's new Emergency Backup Facilities in the outskirts of Tokyo last fall. The installation, housed on three floors of the Tachikawa System Load Dispatching Office, are built to deal with the ultimate disruption--an earthquake knocking out the company's headquarters 40 kilometers away in central Tokyo [see photos, " "].

The Tachikawa building is decoupled from its foundation supports by interposing laminated rubber bearings. "This allows the structure to sway horizontally and survive a 7.3-magnitude earthquake," says Kunio Umesaki, deputy general manager of the Tachikawa service center. A gas turbine generator with fuel for three days is also available should the two power lines feeding the facility fail.

The emergency facilities comprise a substitute central load-dispatching office that oversees all supply and demand in the network, a central telecommunications center, and an emergency task force center. Tepco has also developed its own communications network using wired, fiber-optic, and microwave transmissions, as well as satellite and mobile phone communications.

Should an earthquake disrupt part of this network, vehicles equipped with satellite communications equipment and wireless telephone exchanges can take over and maintain contact between headquarters (or the backup facility) and recovery units. Fleets of vehicles equipped with high- and low-voltage generators, as well as mobile transformers, can also be called into action.

Arguably, one advantage Tepco has over many of its U.S. counterparts is that it is a vertically integrated company: it controls all aspects of its business--from generation and transmission through to distribution and sales. "So in case of accidents, we can all work together to deal with the problem," says Noburo Nakayama, general manager of the Tachikawa System Load Dispatching Office. In the United States, separate companies may carry out some of these functions for the power supplier. "This can cause a problem with communications," Nakayama adds.

In a country as prone to natural disasters as Japan, disruptions come with inevitable regularity. But by maintaining an attitude of vigilant preparedness, Tepco is able to deal with the expected and unexpected and keep its lines humming almost all the time. The utility's success stems from a corporate culture that can be boiled down to adhering to a policy of preparing for the worst, as much as it does from relying on leading-edge technologies to deal with or head off troubles.

This is a prudent attitude, considering that Tokyo straddles three tectonic plates--the Eurasian plate, the Philippine Seat plate, and the Pacific plate--and possibly a fourth. A repeat of the Great Kanto Earthquake that devastated the city in 1932 appears to be a matter of when, not if.

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