# Background

I'm performing some research for a software project that monitors power generation and consumption for a large fictional spaceship. My rationale is I'd like to first understand how real-world power generation works before starting to make the app feel as authentic as possible when using it.

# Basis

My question stems from my current understanding of how the electrical grid works. Energy is generated through whatever mechanism (steam/mechanical, photo-voltaic) and is then stepped up via a HV substation for long distance transmission. Large factories (Steel Mills, Microchip Plants, etc.) may have a substation dedicated to them for their operations. Otherwise, a substation steps HV down to MV for smaller scale distribution (factories, large office buildings, etc.). This is repeated again for LV, for delivery to homes and small businesses. It's a simple model, albeit misleading because it presents a linear chain of flow from source to load, with a single source generator of power. In the real world, there are multiple stations that are running to meet the demand, and they adapt as the demand changes over time.

# Question

Suppose a large event such as a generator station unexpectedly shut down. What equipment would be involved in "rerouting" power to minimize the possibility of blackouts? Or, if a rolling blackout was temporarily implemented because of high demand, what equipment or process would be involved?

# Related Questions

• This is a good question!Well done!This is the kind EE SE has need of. – Daniel Tork Jul 12 '16 at 8:07

What equipment would be involved in "rerouting" power to minimize the possibility of blackouts?

Transmission switching stations re-organize things when there are problems with generators or section of grid: -

As you can see, every generator connects to the (national) grid via a TS. This wiki page should help. Pictures taken from here or here if not a Quora member

• I think you may have dropped below acceptably minimalist level there :-). "Pages from here" does not work for non-[highly invasive permissions requests so not accepted]-Quora members. And the Wiki is a bit of a wade and neither specific nor general enough (IMHO). I've added a link to the Quora source of that image (found with Garglabet image search). – Russell McMahon Jul 12 '16 at 11:46
• @RussellMcMahon The picture reference was just to give credit and I'm not a quora member yet I can see it. The wiki page has a section for transmission stations and that was the point!! – Andy aka Jul 12 '16 at 11:54
• Regardless, I now have a point of reference to start from. Thank you both for your time and effort. :-) – gate_engineer Jul 12 '16 at 15:19

Suppose a large event such as a generator station unexpectedly shut down. What equipment would be involved in "rerouting" power to minimize the possibility of blackouts?

Power grids are engineered to withstand the failure of any one component.

For generator failures: There must be enough spare generation running to cover the loss of the largest generator. This is called "spinning reserve". Note that having spare generators sitting still doesn't help you. A cold generator takes minutes to hours to start, but the spare generation must take over from the failed generator in a period of seconds.

Note: This means that generation companies get paid for keeping generators turning over, but producing no power. People wonder why they are getting paid for producing nothing! The generators aren't producing any power, but they are providing an essential service.

It's also important that the spinning reserve generators be able to react quickly to changing load. "Transient response" to "load swings" are the key words to look for. Big coal / nuclear power plants are no good for this, as they respond slowly to control inputs. Gas turbines are much better at taking swings.

For transmission infrastructure failures i.e. transmission lines, substations - I think Andy's answer has that covered.

We do engineer transmission systems to have at least N-1 redundancy, so we can lose any one component and still keep most of the system running.

I don't have any experience with HV transmission systems, so I will refrain from saying anything more.

Or, if a rolling blackout was temporarily implemented because of high demand, what equipment or process would be involved?

There are two ways to manage excessive load.

The traditional system reacts to excessive load by turning off supply to entire load centres, i.e. an entire substation, or an entire feeder. This is a "load shedding system".

Loads would be turned off in priority order. You would turn off a factory before you turned off a hospital. You keep turning things off until the load re-balances with the available generation.

The other way is to pro-actively manage the load, i.e. using ripple control signals. This turns off specific customer equipment, such as air-conditioners, at times of high demand. This won't help in severe power shortages, so a load-shedding system is still required.

• Shouldn't that be N+1 redundancy? N-1 redundancy seems to mean you have one less generator than you need. – user253751 Jul 13 '16 at 7:37
• Correct. I made a typo. Please feel free to edit (I am on a potato.) @immibis – Li-aung Yip Jul 13 '16 at 9:31
• I believe edits not by the author need to change a minimum of 6 characters. – user253751 Jul 13 '16 at 9:33
• @immibis I looked it up, and it really is N-1. The phrasing is: If you have N items, you can survive with N-1 of them running. – Li-aung Yip Jul 15 '16 at 10:06

The actual piece of equipment in a transmisson substation that "switches" electricity around is the Quadrature Booster, otherwise known as the Phase Angle Regulating Transformer. Essentialy, by changing the phase of power with respect to the source, you change the resistance to energy flow, thereby regulating the flow of power through a particular segment of the grid.