The art of managing compromises - Embedded.com

The art of managing compromises

It was a horrible. Traffic lights stopped working. At Starbucks the lattes cooled. And when the cell phones went out, drivers were left with nothing to do but drive.

It was wonderful. New Yorkers were nice to each other, gave strangers rides home. There was no looting. The people had a snow day in August, a crisis that turned into a chance to get out of the house and meet the neighbors.

The Great Power Failure of 2003, with its naive and excessive press coverage, left the nation feeling our electric grid is rotting. We're told deregulation or Enron-like greed has let the power distribution system crumble. Congressional investigations will surely turn up a scapegoat.

Seems to me the system might be a bit over-designed. One failure in 25 years? That's astonishing, a phenomenal record.

Talking heads might claim we need a more reliable grid, but they're spouting nonsense. If it is indeed necessary to update the system, “more reliable” isn't a valid engineering specification. What are the numbers? Is one failure per decade acceptable? One a century? We engineers can build systems of astonishing reliability, but is the public willing to foot the cost?

A better system might need more redundancy; do you want that extra power plant in your back yard? How much pollution will we tolerate — especially now that older power plants will be exempted from certain emissions regulations?

My dad worked on the F-11F in the 1950s. When the hydraulic test jig couldn't break the tail assembly the Navy complained mightily because the aircraft was too strong. Engineers all, they understood that excessive strength meant too much weight and reduced speed, altitude, and fuel range. The World Trade Center was designed to withstand 140-knot winds, not those of infinite velocity. Offshore drilling rigs are typically good for 100-foot waves, not the eye-popping but utterly unrealistic monsters in The Perfect Storm . Perfection is rarely a design goal.

Engineering is the art of managing compromises. Make things strong enough but don't degrade performance. Build a reliable system, but at an acceptable cost.

Some complain that the power failure compromised certain critical services, yet it seems most hospital ICUs and such had their own emergency backups. It's foolish to make the entire grid perfectly reliable for the few who cannot stand an interruption. Just as centralized mainframes gave way to distributed servers, critical users should have their own local uninterruptible power supplies or generators. That solution is cheaper overall and more dependable, since a minor tree fall might yank the plug for a cluster of houses or buildings but have no impact on the grid.

Occasional failures have a certain social value, as well. They remind us just how dependent we are on a steady flow of electrons. Kids are astonished at all of the things that no longer work when that stream disappears.

And maybe each of us has a responsibility to conserve power — a much cheaper route than replacing the grid. Swap those incandescents for low-power, long-lived compact fluorescent bulbs. They're only about five bucks and last nearly forever. Notch up the A/C temperature a bit. Unplug those thieving wall transformers when you're not charging the phone, drill, or laptop. Turn the computer off for the night.

My hat is off to those engineers who have built a system that powers every bit of our lives, with astonishing reliability.

Jack G. Ganssle is a lecturer and consultant on embedded development issues. He conducts seminars on embedded systems and helps companies with their embedded challenges. He founded two companies specializing in embedded systems. Contact him at . His website is .

Reader Feedback

Jack,

But keep in mind that a well-designed system should degrade 'gracefully'. An overloaded system may degrade in performance but total failure (if potentially damaging) is poor engineering by all terms. It might be too costly to modify the power grid, but I am sure that it can be made much more intelligent against potential overloads for a fraction of its cost (electronics is cheap!) so that it will degrade more gracefully.

Ali Tugrul Anildi
Electrical Engineer


I think your article misses the point of concern about the grid in the North East and California, In both areas, back in 1980, the grid and generation had safety margin, but each year more load has been added faster than the grid has been upgraded — it will get to the point where it will fail with surprising regularity in just a few years if something does not change — conservation will help, but you will also need a moratorium on immigration legal and illegal, a freeze on building — only if you are tearing something down do you get to build a replacement, The number of home appliances will need to be be regulated and licensed. Sound strange — In Finland where all energy must be imported many of these measures are in place. Energy use is highly taxed, but failure of the grid when it is -40 C below in winter can be fatal.

Part of the price of a smooth running growing and vibrant economy is a reliable electrical system, try and over optimize the grid cost, and you won't be able to handle things like population growth, immigration, new construction etc.,

It's just as bad as not putting enough RAM or MIPS in an embedded system, or worse yet, undersizing the power supply by 50ma. All give something that is often maddening, and far more wasteful than the solution when the countless wasted hours are added up.

Fixing the grid for the next 25 years will cost 100 billion, this compares to 5 billion a day for every day it's down — 20 days of down time and you've bought a grid upgrade. We've already had several days in California, and one for the East Coasters.

It's not going to be easy — there is going to have to be short term conservation because it's gone to far. New grid capacity is a 5 year and longer type activity and we're really playing catch up. There is right of way to be acquired, impact statements to be done, a whole slew of engineering as to how to best patch in the additional grid mesh.

The sad thing is there are countless other infrastructure problems. Dams, Bridges, Roads, Canals, Locks, Tunnels all that probably need some kind of maintenance or upgrading. America has gone from 220 million to nearly 300 million people, but the interstate highway system for example is still built for that 220 million. I dodge pot holes on the way to and from work on a daily basis as do most of us. (I guess buying an SUV would get me over more of the bumps, as one can't really drive a car at even the speed limit with out the risk of bottoming out or shedding parts).

Bill Murray
Baseband Engineer
Nokia


You hit this issue right between the eyes. I'm not a power engineer… it didn't seem all that glamorous when I attended college. It took me a while to overcome my naivete on the complexities of power distribution. I normally would not take the time to respond to an article, but my colleagues and I had the same reaction that you voiced. I've not seen any other articles that stated the obvious as succinctly as you did. Hopefully our government doesn't go overboard with a “naive” corrective action to the so-called antiquated US power grid. Just thought you should know that I appreciated your article.

Doug Conner
Hardware Tech Lead
Smiths Aerospace

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