The modern world depends on electricity.
It's not just a luxury we use to power our
devices and enjoy our free time.
It's not even just the convenience of having light heating
and cooling in our buildings.
Electricity is a crucial resource, especially in urban areas, providing
public security, safety and health, and making possible everything from
emergency response to modern medical care and hospitals to even
the other utilities we require, like fresh water and sanitation
systems.
But unlike those other utilities, electricity can't be created, stored
and used at a later time.
The instant it's produced, it's used, no matter how far
away the producer is from the user.
And the infrastructure that makes all this possible is one
of humanity's most important and fascinating engineering achievements.
Hey, I'm Grady, and this is practical engineering.
On today's episode, we're talking about the power grid.
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Like most people, you probably take the grid for granted.
Electrical infrastructure is so ubiquitous, it's easy not to notice
that most of our power grid is out in the
open for anyone to have a look.
I happen to be one of those people who does
want to have a look, and hopefully by the end
of this video series on electrical infrastructure, you will be
too.
This video is geared toward North America, but most of
the concepts will apply to any other part of the
world.
And just to give you a sense of scale, there
are only four distinct electrical grids that service essentially all
of North America.
You have the two big ones, Western and Eastern, and
the two electrical separatists, Quebec and Texas.
Depending on your definition, an electrical grid can be considered
one of the world's largest machines.
So how does this machine work?
The basic function of generating electricity and delivering it to
those who need it may seem simple.
I can hook up a small generator to a light
and boom power grid.
With the cost of solar panels reaching record lows, many
are exploring the possibility of generating all the power they
need at home and forgoing the grid altogether.
But a wide area interconnection, that's the technical term for
power grid, offers some serious advantages in exchange for increased
complexity.
Here's a simplified diagram showing the major components of a
typical power grid, and will follow the flow of electrical
current as it makes its way through each one.
We start with generation, where the electricity is produced.
There are many types of power plants, each with their
own distinct advantages and disadvantages, but they all have one
thing in common.
They take one kind of energy and convert it into
electrical energy.
Most power plants are located away from populated areas, so
that electricity they create needs to be efficiently transported.
That's handled by high voltage transmission lines at the plant.
Transformers boost the voltage to minimize losses within these lines
as electricity makes its way to the areas that need
it.
Once it reaches populated areas, Transformers then step down the
power back to a safer and more practical voltage.
This is done at a substation which also has equipment
to regulate the quality of electricity and Breakers to isolate
potential faults.
Some energy customers draw power directly from the transmission lines,
but most are served from feeder lines that carry power
from the substation.
This part of the system is called distribution.
From the feeders, smaller Transformers step down the voltage to
its final level for industrial, commercial, or residential uses before
the electricity reaches its final destination.
Rather than a constant flow of current in a single
direction called direct current, or DC, the vast majority of
the power grid uses alternating current, or AC, where the
direction of voltage and current are constantly switching 60 times
per second.
In North America, the major advantage of AC power is
that it's easy to step up or down voltages, a
critical part of efficiently and safely moving electricity from producer
to consumer.
The device that performs this important role, called a transformer,
is as simple as a pair of coils next to
one another.
A varying voltage in one coil induces a voltage in
the other coil proportional to the number of turns in
each one.
If the current doesn't vary, like in direct current, the
transformer can't do any transforming.
It's helpful to think of the grid as a marketplace.
Power producers bring their electricity to the market by connecting
to the power grid, and power consumers purchase that electricity
for use in their home or business.
The economics and politics of the grid are so much
more complicated than this, but the important part of the
analogy is that in many ways, the power grid is
a shared resource.
Because of that, it needs organizations to oversee and establish
rules about how each participant in the producing, transmitting, and
consuming of power may use it.
And there are three overarching technical goals that engineers use
to design and maintain the power grid.
The first one is power quality.
Our electrical devices and equipment are designed assuming that the
power coming from the grid has certain parameters, mainly that
the voltage and frequency are correct and stable.
Some devices even count the oscillations in the AC grid
power to keep track of time, so it's critical that
grid frequency not deviate.
Changes in voltage can lead to brownouts or surges that
damage connected equipment.
One of the benefits of large power grids is electrical
inertia.
All those huge spinning generators connected together provide momentum that
smooths out the ripples and spikes that can occur from
equipment faults or quickly changing electrical loads.
The next technical goal of the grid is reliability.
If, like most people, you take the constant availability of
power for granted, that's by design.
Much of the grid's complexity comes from how we manage
faults and provide redundancy so that you're rarely faced with
blackout conditions.
It's another inherent benefit of a grid that electricity can
be rerouted when a piece of equipment is out of
service.
Whether it was planned or otherwise, the final goal of
the power grid is simply that the supply meet the
demand.
Electricity production and consumption happen on a real time basis.
That means if it's plugged in, the light from the
screen you're watching right now was a drop of water
in a turbine or a breeze across a windmill just
microseconds ago.
And by the way, did you call your utility and
let them know that you were going to be turning
on your computer or phone to watch this video?
I'm willing to bet you didn't, Which means not only
did they have to adjust their production up to match
the extra load, but they had to do it immediately
without any warning whatsoever.
Luckily, having millions of people connected to the same grid
smooths out the demand created by individuals, but load following
is still a major challenge.
For the most part, electrical demand follows a fairly consistent
pattern, but factors like extreme weather can make it difficult
to forecast.
Grid operators balance demand by dispatching generation capacity in real
time.
The cheapest sources of power are used to fulfill the
base load.
That's more consistent and higher cost.
Sources are used for peaking when demand exceeds the base,
But it's not as simple as flipping on a switch.
Large power plants can take hours, days, or even weeks
to start up and shut down.
Equipment needs to be taken out of service for maintenance.
Fuel costs fluctuate.
Renewable sources like wind and solar can have massive and
unpredictable variations in capacity, providing irregular sloshes of power to
the grid.
You can see why balancing electricity supply and demand is
this fantastically complex job of taking into account all these
considerations, some of which are predictable and some of which
aren't.
That's part of the reason we're trying to make the
grid smarter by using software, sensors, and devices capable of
communicating with each other.
On the supply side, this can allow computers and software
to do what they do best, take in and process
huge amounts of data to help us make decisions about
how to manage the grid.
But a smart grid can also help on the demand
side as well.
Unlike most of the goods we buy, consumers don't have
a keen understanding of power, how much we're using, or
how much it should cost depending on the time of
day or year.
A smart grid can take away some of that obfuscation,
allowing us to make decisions about how we use electricity
in our day-to-day lives.
Ultimately, the smart grid can help us use and take
care of this huge machine, this shared resource we call
the power grid, more effectively and efficiently now and into
the future.
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