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UNDERSTANDING THE POWER GRID by Don Oswald

Warning the following is extremely boring. I work for Siemens energy and my job for the last 10 years has been building wind turbine farms all throughout the United States and commissioning the transmission lines that connect the power to the grid. I thought I might say a few things in hopes of maybe clarifying to people who might want to understand some basics about the grid that our men and women are so diligently trying to restore. And explain what is probably happening here in Wedgefield.

Main parts in order: Power generation, step-up transformers, transmission lines, substation, distribution lines, step-down transformers, the customer.

The power grid is a delicate dance. There is no way to store the electricity generated, so the power produced must match the power demanded (this is called the load). During the storm many trees and wind most likely destroyed several transmission and distribution lines, when that happens the neighboring lines have to pick up the extra load, if those lines are near capacity then they will fail too, then you have a domino effect of lines gaining more and more load and more and more failures. The power generation station (which is probably Staton) will more than likely shut down to protect it’s self from malfunctioning because, during the cascade failure of the lines, more power is being produced than is needed (think of it as the power station overheating.) This can also happen to the substations.

Steps needed to restore power:
1. Locate the problem. Problems need to be identified by personnel and a line can be as long as 20 miles.

2. Isolate the affected area by opening switches in key areas (sometimes when you open the switch to isolate a problem, you will also kill power to areas that didn’t have an issue, to begin with)

3. Install grounds around the lines to protect the workers from possible back feed (if people are using generators to power their entire house, makes sure that the connections were done by an authorized representative of the electric company, because there is always a possibility that the generator you are using is back feeding the line (basically meaning instead of power coming from the grid to your house, you are now sending power from your house to the grid). This is the number one reason linemen are killed in the line of work.

4. Remove trees if that’s the issue.

5. Repair the damage (lines, step-down transformers etc.) If you saw beautiful green and blue explosions in the neighborhood on Sunday, that was a malfunctioning transformer (the transformer takes the voltage from high voltage (typically around 7kv) into your home at low voltage). This is not good and is very time consuming to fix, and I saw at least 3 explosions.

6. Test the new equipment, remove grounds and close switches.

7. Restore the power, if there is a trip while restoring power, then repeat the process.

Now this is just for one downed line, I imagine they are dealing with thousands right now, and please keep in mind, that being a lineman is one of the top 10 most dangerous jobs in the world. Every year 30-50 line men per 100,000 are killed.

People have been saying they see flickering with the lights, this typically is not a good sign, it usually means that they have tried to restore power and there is still a fault somewhere, meaning there is a problem that they don’t know about and the process starts over again.

One more thing it could mean, and this is important if you actually were resilient enough to read this entire post. When the power died everyone had their AC on, most people still have their AC thermostat in the on position, that is an extremely huge amount of load for the grid to tackle all at once. Think about energizing 1,000 homes all at once, and 1,000 A/C’s try to start up all the same time. It is very hard for the engineers to account for all this instantaneous inductive power. This can cause trips, hence the flickering of lights. This means more distribution lines will need to be fixed to handle the unexpected load which translates to more waiting time for our electricity. If everyone would turn their AC off we could possibly get power back sooner.

Once power is restored to your home, you are no longer a key factor to the initializing of other systems and can run your A/C all you like. Once power is restored to your home it is not uncommon to lose it again for short periods of time. As other lines are trying to be restored, troubleshooting by the technicians may warrant the need to open (electrical turn for off) your circuit to work on those lines as many of us are connected via the same junction box.

There are two types of power lines, above ground and underground. Above ground lines, are exposed to more elements that can damage them but are very easy to work on. Underground lines are safer from failure but are time-consuming to repair. If you ever see a power company digging, expect a longer wait time for your electricity.

Sidebar for nerds: Our grid has ancient technology. It was built in the 1890’s and has had small improvements every 10 years. Since then not much has really changed from the 60’s. Smart grids are currently being developed but as I said before, they are in their infancy. The next generation very well could see a power grid that is self-healing, has two-way communication from customer to the power plant and visa versa with a digitized grid that will tell the technicians exactly where and what the problem is reducing outage time by 300%. It will be expensive but you get what you pay for….. But I digress.

I hope this has been informative and at least a bit interesting, if your reading this last paragraph then it must have been, and congratulations for not falling asleep.