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Blackouts? never Again! (But...)

We ask merchant grid developers if anything can ever be done.
Fortnightly Magazine - October 1 2003

Schroeder believes a lot of utility companies would be loath to put in the money needed to upgrade the transmission system, unless they are truly into that business. "I think others will take another look at it and say maybe these guys like Trans-Elect are the way to go-a) they take over the problem, and b) they are motivated to fix it because that is all they do," he concludes.



George Loehr: A Plea for Direct Current

The decreased lead time for new generating units (now a few years, down from 10 to 15 years a decade ago) as well as what George Loehr, a member of the executive committee of the New York State Reliability Council, calls "a change from a culture of reliability to a culture of competition," led to Loehr's innovative plan for making the grid more reliable. His plan starts with making the physical system simpler via use of high voltage direct current (DC), with smaller interconnections. For example, Loehr would take the Eastern Interconnection, which is about 600,000 MW, and break it up into 10 smaller interconnections of 60,000 MW each.

He proposes cutting the two huge North American grids into a series of smaller grids, with DC ties equaling or matching today's AC ties.

"I took published NERC data that show on the existing AC system the transmission transfer capacity between each pair of regions that has direct ties," he explains. "I said, 'Let's figure out how to provide enough DC capacity to match that existing AC capacity. Then we'll take some of those AC lines that we have opened to separate these smaller interconnections and use them for DC.' There is no reason you can't use an AC line for DC. The copper doesn't care whether it carries a direct current electron or an alternating current electron.

"In fact, when you work out the real technology of this, you find out you can use a slightly higher voltage in DC than in AC for several reasons. One is you don't have to worry about switching surges like you do in AC, and you only need two phases instead of three, because you have a positive and a negative. So, if you had a double circuit line with six conductors (six phases), you could operate three of those wires as the positive pole and the other three as the negative pole. With a single circuit line on a horizontal tower arrangement, you can use the outside phases as the positive and negative poles, and you can make the inside phase a fully insulated neutral. So if you lost the positive or negative pole you can put in automatic equipment to automatically switch that into place-to replace the faulted pole with the inside wire, which would be fully insulated.

"You convert some of these AC lines into DC, and now comes the rub: You put in converter stations at each end of the lines to carry the amount of power you want to carry, and that is where the money comes in. But the technology has been