Why are Power Grids so Large?

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mbrooke

Batteries Included
Location
United States
Occupation
Technician
Why are power systems so large and interconnected? For example, what technical obstacles prevents the US eastern interconnection from being 8 isolated islands? Why not separate them by ISO/RTO? Why does every power grid in the world strive to be as large as geography allows?

Better yet why not have scattered power plants about (with redundancies of course) feeding load radially?
 

Hv&Lv

Senior Member
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-
Occupation
Engineer/Technician
generation only...

How well do generators work at half load?

peak sharing, and generation sharing.

also costs are a large factor.
let’s say you have a peaking plant that’s not running. Peaking plants are expensive to run...
a neighbor has a base generation plant that is running at two thirds capacity and you are maxed out on your base plants. You want to turn on a peaking plant or buy from the neighbors base plant?
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Over the last century,the state and federal regulatory rules and the capitalist free market system have determined that large systems provide, overall, the best value and reliability for both customers and shareholders.

Not that that is the best system technically, but how our economic system works.

With some big stumbles along the way like Enron... :dunce:
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
generation only...

How well do generators work at half load?

peak sharing, and generation sharing.

also costs are a large factor.
let’s say you have a peaking plant that’s not running. Peaking plants are expensive to run...
a neighbor has a base generation plant that is running at two thirds capacity and you are maxed out on your base plants. You want to turn on a peaking plant or buy from the neighbors base plant?


Why not have a bunch of base plants, and run turbines seasonally in rotation? Though you will always be running your say 5 turbines at reduced load in case one goes off line.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
Over the last century,the state and federal regulatory rules and the capitalist free market system have determined that large systems provide, overall, the best value and reliability for both customers and shareholders.

Not that that is the best system technically, but how our economic system works.

With some big stumbles along the way like Enron... :dunce:

Perhaps, but even in communist countries the grid was a mesh. In fact I don't know of any sub-sectional grids... that is unless you look to the Texas interconnection.
 

Todd0x1

Senior Member
Location
CA
concatenation. the more interconnected capacity and load there is the more you smooth out peaks and valleys in demand (although I would hazard a guess that solar and wind is really screwing this up)
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
concatenation. the more interconnected capacity and load there is the more you smooth out peaks and valleys in demand (although I would hazard a guess that solar and wind is really screwing this up)

That and faults... Think of a mattress spring or a stone thrown into a body of water.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
That and faults... Think of a mattress spring or a stone thrown into a body of water.

Faults - yes. Having an interconnected supply means that local faults can be isolated and dealt with without discontinuity for customers.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Why are power systems so large and interconnected? For example, what technical obstacles prevents the US eastern interconnection from being 8 isolated islands? Why not separate them by ISO/RTO? Why does every power grid in the world strive to be as large as geography allows?

Better yet why not have scattered power plants about (with redundancies of course) feeding load radially?
One answer: Migration toward the mean. The larger a grid is the closer its steady state load approaches statistical averages. Microgrids are harder to manage.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
You mean like one tree near Cleveland that cascaded into 50 million out of power??
proof alarms don’t always work, but still...

what, you get tired of your avatar??
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
You mean like one tree near Cleveland that cascaded into 50 million out of power??
proof alarms don’t always work, but still...

what, you get tired of your avatar??



Yup, and also Italy, India, Brazil, ect. SCADA also opens up security issues.

Decided to change things up a bit. After all, I don't bite. 🐍 But I sure am curious to the point of bug eyes. :geek:
 

dereckbc

Moderator
Staff member
Location
Plano, TX
They can be large or small. Take Texas for example is not interconnected to the AC Grid. Texas interconnects are DC only so when there is a area blackout, TX will not be effected.

To answer your question th egri dis the most complex machine man has ever built. It is done for redundancy and economic. Think of it like cell phone towers. If you loose a genertation station, the neighbors pick up the load. The USA East and West Grids are in a secret location and use DC inter-connects.
 
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