Smart Transformers Will Make the Grid Cleaner and More Flexible - by Subhashish Bhattacharya

The solid-state transformer is poised to remake the electrical distribution grid.

It would be hard to overstate the importance of transformers in our electrical networks.  They’re literally everywhere:  on poles and pads, in substations and on private property, on the ground and under it.  There are probably dozens in your neighborhood alone.  It’s hard to imagine a world without them.  But my colleagues and I are doing just that.

In the distribution system, transformers typically take medium, or “primary,” voltages measured in the thousands of volts and convert them to secondary voltages—such as 120, 240, or 480 volts—that can be safely delivered to homes and businesses all over the world.  It’s an approach that’s been used since before alternating current won the war of currents in 1892.  It is difficult to name another electrotechnology that has survived as long.

Nevertheless, it is time to start thinking beyond the conventional transformer.  For one thing, transformers are bulky.  They’re often cooled with oil, which can leak and is difficult to dispose of safely.  Crucially, transformers are passive, one-way tools.  They aren’t designed to adjust to rapidly changing loads.  This shortcoming will fast become intolerable as distributed power sources such as wind turbines, solar panels, and electric-vehicle batteries feed more and more energy to the grid.

Happily enough, research into a new kind of technology—one that could address all of these limitations—has been making significant strides.  Thanks to recent advances in power electronics, we can now contemplate building smart, efficient “solid-state transformers,” or SSTs.  They promise to handle tasks that are difficult if not impossible for a conventional transformer to accomplish, such as managing the highly variable, two-way flow of electricity between, say, a microgrid and the main grid.  What’s more, these smart transformers can be modular, making them easy to transport and install.  And they can be significantly smaller than an equivalent conventional transformer—with as little as about half the weight and a third the volume.

In the near term SSTs could be a boon for disaster-recovery efforts in places with damaged electrical infrastructure and for settings such as naval vessels, where volume and weight are at a premium.  Further in the future, they could redefine the electrical grid, creating distribution systems capable of accommodating a great influx of renewable and stored energy, dramatically improving stability and energy efficiency in the process.

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