Question about the Grid

[mcclary's electrical]

Interesting topic,

What about the nationwide one hour blackout coming up, where everyone is supposed to turn off their lights for one hour. Is this enough load that the power companies actually have to adjust something.?? Does it actually save anything??. I find it hard to believe that a nuclear reactor will have to be "backed down" for an hour ,,,,,in order to actually save anything.

 

[chris kennedy]

What about the nationwide one hour blackout coming up, where everyone is supposed to turn off their lights for one hour.

When is this?

 

[mcclary's electrical]

When is this?

They aired the commercial last night,,,I was sleepy and missed the date,but it's coming up

 

[mcclary's electrical]

When is this?

They aired the commercial last night,,,I was sleepy and missed the date,but it's coming up




8:30pm March 27

Shed as much power as you can for one hour

 

[cpal]

no problem I should be sleeping by then:grin:

 

[kwired]

what is the point, people are either energy concious or they are not.

How many people will just turn off the lights and get in their car and use other form of energy if they are actually participating in this.

We are a spoiled nation and can not live without technology and luxuries.
If the power does go off even if only for a few hours it is almost as bad as having a death in the family for many.

 

[K8MHZ]

Back to the OT.

Scale down a bit. What happens when your portable generator puts out more power than is being produced?

For one thing, it can't. It's either being made into juice or used up as heat. Same for a big steam turbine.

As the load increases on your home generator, the fuel consumption increases.

The same is true for steam turbines and gas turbines. It takes less fuel to free wheel any generator than it uses under a full load.

Agreed, when it comes to a steam turbine it is hard to imagine a throttle and a governer being employed but that is just how it works. There are valves that regulate the steam pressure.

Now here is where the big difference is. You can't just back down the steam supply like letting off the throttle. If the amount of steam being rejected by the regulation valve exceeds the amount that the liquid pumps are able to remove from the system, the steam is explosively discharged into the atmosphere via pop off valves. This is known as a 'power pop' and if you are anywhere near the exhaust of one of these when they pop off you will never forget it. I was working on the top of a 6 turbine steam plant when they popped off at 1250 psi. I thought the world was coming to an end. Some systems can hold up to 2500 psi before they need to be popped. That is like a large bomb going off. Following the explosion there is a deafening rush of steam that sounds like a jet fighter engine that lasts from a few seconds to a minute or two. It's really, really scary to be around. Especially when you aren't expecting it. Trust me, I know from first hand experience.

Gas turbines, as you can imagine, just require less natural gas which can be turned off instantly via throttle valves.

It may interest some of you to know that in some of the gas turbine peak plants there are steam turbines that run off the heat from the exhaust of the gas turbines. The process is called Heat Recovery Steam Generation, or Hertzig, as we referred to it. The pic on this Wiki page looks just like the one I worked on in Zeeland, MI.

http://en.wikipedia.org/wiki/Heat_recovery_steam_generator

 

[K8MHZ]

Another thing....

We utilize a pumped storage plant to store excess energy during produced during off peak hours and then use hydros to create more energy during peak hours.

http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant

 

[charlie b]

I like your analogy

Many thanks.

...yet, I don't believe anyone has mentioned the concept of more energy is generated than is consumed. Continuing with your analogy, it would be similar to going up the hill in first gear, though you could have made it up the hill in second gear at the same speed.

Not quite the same thing. You are now bringing efficiency into play. In first gear, you use more energy on the input side, in order to obtain the same result (i.e., the same uniform speed up the hill). That makes the process less efficient. But the forces of wind resistance and friction and all the rest are still balanced by the car's output power, and that is why the speed is constant.

 

[LarryFine]

When the grid is unloaded, the generating frequency rises for a moment, and when the load increases, it drops for a moment. "Cruise controls" act to bring the frequency back into synch.

As with all things under the effects of Ohm's Law, the voltage across loads and the impedance of loads results in the current that flows. Those factors determine the power delivered.

 

[Smart $]

Not quite the same thing. ...

I did say similar

 

[LarryFine]

It is impossible to generate more power than is consumed (losses included.)

The voltage is what it is, and the current will be whatever it ends up being.

The generators will simply be easier to spin if they're less heavily loaded.

 

[mivey]

What about the nationwide one hour blackout coming up, where everyone is supposed to turn off their lights for one hour. Is this enough load that the power companies actually have to adjust something.?? Does it actually save anything.

If enough people do it, we will save a bunch of energy: until they can get the grid back up.

 

[Smart $]

It is impossible to generate more power than is consumed (losses included.)

...

Your statement depends heavily on which definition of "consume" is used. By one definition, losses are lost or wasted and not consumed. Yet by another definition?and apparently the one you are using?consume can also mean spend or utilize wastefully.

The latter is like running a full tank of gas through my generator with no connected load

 

[LarryFine]

Your statement depends heavily on which definition of "consume" is used. By one definition, losses are lost or wasted and not consumed. Yet by another definition?and apparently the one you are using?consume can also mean spend or utilize wastefully.

Losses must be generated, so you surmise correctly.

The latter is like running a full tank of gas through my generator with no connected load

Exactly. If there's no load, no power is generated (this time, excluding losses.)

 

[Smart $]

...

Exactly. If there's no load, no power is generated (this time, excluding losses.)

Also true...

But my point was that I could also say more power is generated than consumed regarding the "Grid", and it would still be an accurate statement.

 

[LawnGuyLandSparky]

This has turned into one vexing paradox...

 

[robbietan]

Me and my buddy recently took a road trip and came up with a question neither of us knew the anwser to. What happens if more power is being put on the grid than what is being consumed (is it even possible). I use to work at a plant that had a small cogeneration portion, about 13 megs, and we would run as hard as we could all the time to maximize our output, does there ever come a time that power would not be utilized, or do some generators go offline due to no demand. Maybe a silly question to some but it has me wondering.

coming from the power company (ehem) I could definitely say that more power is present in the grid than the power being consumed. our grid here in the Philippines have a maximum demand of 4 GW. so, generators provide 4.4 GW - the 0.4 GW is referred to as "spinning reserve".

why? the grid has to be protected from blackouts caused by sudden loss of generating capacity. if a power plant suddenly fails, there is enough reserve power to prevent other power plants from shutting down to protect themselves. power plants have safeties that shut them down when the power demand is too much for their capacity.

in the other side, power plants do shut down when there is too much power in the grid. the grid operator determines how much power is needed for the reserve and tells power plants with expensive fuel either to lower their generation or shut down entirely. usually this occurs during looong holidays where there isnt much demand for power. here in the Philippines, that is usually the Lenten season

 

[don_resqcapt19]

Isn't a "spinning reserve" more of a "hot standby"? That is it does not put power onto the grip unless it is needed.

 

[richxtlc]

Isn't a "spinning reserve" more of a "hot standby"? That is it does not put power onto the grip unless it is needed.

You are correct, the spinning reserve is the available generation in case of the loss of the largest unit or tie feeder. It is the capacity that is available, not excess MWs that are just hanging around on the grid. All properly run electrical systems have spinning reserve or face the loss of the system in the event of loss of a major piece of generating or transmission equipment.