Controlling the Smart Grid
by Igor Mezic
Buildings and Design Solutions Group Head
The smart, green power grid is coming - ready or not!
Technological advances of sustainable power-producing technologies such as wind turbines combined with decreasing costs will result in a large percentage of conventional energy sources being replaced with alternative ones. The nature of electric loads will change as well. Electric cars of the future may be powered using the electricity produced by neighborhood microgrid sources such as solar panels and wind turbines, and may also serve as storage for electricity to return it to the grid when needed.
But this creates a headache for engineers concerned with robustness and efficiency. Just as the depth of the current economic crisis is due in part to embedded interconnectivity of the world’s economies – such that a small initial disturbance in an obscure trading mechanism propagate throughout the world's banking system – so too can a hiccup in a local microgrid (e.g., a dying car battery) bring down the whole coastal powergrid. Think it can’t? In 2003, a blackout of a large portion of the eastern national power grid was precipitated by environmental uncertainty - a tree branch fell on a power line - causing a disturbance that propagated rapidly and caused one power plant after another to fail. The likely occurrence of such events becomes larger in a world of a power grid with subcomponents whose power and storage capacity fluctuating wildly.
So, we need the smart grid to be really smart.
In Mezic's group at UC Santa Barbara, research is underway to elucidate core causes of instabilities leading to large disturbances and failure of catastrophic proportions. It is the coupling of architecture and dynamics of the system that matter the most. If two parts of the system are completely separated from each other, a big disturbance in one will, of course, not influence the other. But, if the subsystems are connected, even weakly, and the dynamics is resonant, a small disturbance in one subsystem can grow, spill to the other part and cause the whole system to fail. This is true even if there are controls in place attempting to stabilize one side - the phenomenon is of the emergent kind, and the only way to control it is to act early at the root cause or provide system-wide regulation that prevents catastrophes (eerily reminiscent of our current economic situation). Similar analysis uncovers architectures that are stable and energy efficient at the same time.
A recent GreenTechMedia posting about GE’s work in developing and implementing smart-grid technology shows that the needed advances are real and happening now. This is an essential part of an overall energy efficient solution to providing clean power.