Generators and Motors
[Home] - [HELP] - [Forums] - [Articles] - [Photo Gallery] - [Groups] - [Chat] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] - [Tools]

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion
Forgot Password? Join Us!

Notices

Generators & Motors General Discussion Antique Generators, Light Plants and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Motors General Discussion

Balancing the load - On a grand scale


this thread has 10 replies and has been viewed 1177 times

Reply
 
Thread Tools Display Modes
  #1  
Old 03-18-2010, 02:22 AM
John Newman, Jr.'s Avatar
John Newman, Jr. John Newman, Jr. is offline
Subscriber
 
Join Date: Apr 2005
Location: Saint Louis, Missouri, USA
Posts: 4,634
Likes: 554
Liked 2,637 Times in 1,358 Posts
Default Balancing the load - On a grand scale

The subject of load balancing has been discussed here numerous times and for most of us it usually involves keeping both legs of a 240 / 120 system within their rated capacity, or in other cases managing a 3 phase system.
Another consideration is the amount of 'droop' the system can handle when a large load is dropped onto the generator.
Imagine having to manage a system where, within a few minutes time, a 3GigaWatt (That's 3000 MegaWatts) load would be switched on and you have to keep the grid stable.
That is this guy's job:
http://www.wimp.com/britskettles/
__________________
John Newman, Jr.
Saint Louis, MO

I Can Probably Fix That
Reply With Quote
The Following 2 Users Like This Post:
Sponsored Links
  #2  
Old 03-18-2010, 04:54 AM
IanR IanR is offline
Email Not Working
 
Join Date: Sep 2005
Location: Palm Bay, Florida USA
Posts: 34
Likes: 1
Liked 1 Time in 1 Post
Default Re: Balancing the load - On a grand scale

That is relly impressive. Huh, no pressure at that job
The funny thing is, I would have thought, in this day and age, it would have been more automated.
Reply With Quote
The Following User Likes This Post:
  #3  
Old 03-18-2010, 09:23 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 1,928
Likes: 35
Liked 328 Times in 294 Posts
Default Re: Balancing the load - On a grand scale

mostly it is automated, such that the most expensive is dropped first and least expensive added first with due consideration to transmission loss and transmission capabilities.

a utility engineer from our street told me in the 1960s that the fellow running the board could save or loose his yearly salary in a few minutes.

back then it was all coal and hydro.

today it is that plus nuke for the big load and gas turbine for the spot needs
Reply With Quote
  #4  
Old 03-18-2010, 09:26 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 1,928
Likes: 35
Liked 328 Times in 294 Posts
Default Re: Balancing the load - On a grand scale

PS

dropped or added includes the output power raised or lowered
Reply With Quote
  #5  
Old 03-18-2010, 09:31 AM
Elden DuRand's Avatar
Elden DuRand Elden DuRand is offline
Subscriber
 
Join Date: Nov 2004
Location: Port St. Joe, Florida USA
Posts: 5,765
Likes: 7,483
Liked 4,033 Times in 1,785 Posts
Images: 6
Default Re: Balancing the load - On a grand scale

John:

Add to the pressure ..... It takes several minutes to get the largest turbines up to speed so the startup time must be considered.

I guess that they start the units they think they'll need ahead of time so they are ready to go online when needed. I also suppose they could have them online and idling at zero power output 'til needed, then they could either increase the voltage or the input to make them push kilowatts into the grid.

Interesting stuff.

Take care - Elden
http://www.oldengine.org/members/durand
__________________
Take care - Elden
http://www.eldensengines.com
Reply With Quote
  #6  
Old 03-18-2010, 09:39 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 1,928
Likes: 35
Liked 328 Times in 294 Posts
Default Re: Balancing the load - On a grand scale

I remember that with the two main steam turbine generators operating seperate busses and going to one in port required first paralleling then picking up the load on one as the other shed load. then tripping the lightly loaded gen off line. repete the proceedure shifting to shore power
Reply With Quote
  #7  
Old 03-18-2010, 10:09 AM
snowcountryfarmer snowcountryfarmer is offline
Registered-II
 
Join Date: Nov 2008
Location: North Country, New York
Posts: 62
Likes: 8
Liked 22 Times in 15 Posts
Default Re: Balancing the load - On a grand scale

Hmmm....I would say that a bit of drama has been added here. Certainly this is not a problem unique to Britain either.

Usually, about 5 o'clock in the morning, as chillers cycle on, lighting, etc. the power demand of large cities is staggering, in terms of block loading. This is a major problem in older cities, or older parts of cities. For example, in lower manhattan, in New York City, it is fairly typical to experience a voltage drop of 10% or more between 5 and 6 am.

The interesting thing to me, is that Britain actually has frequency deviation issues. Here in the US, the electrical grid is so large, that the frequency is VERY stiff. Voltage can fluctuate quite a bit based on the stiffness, or weakness of an area's lines, distance from transmission lines, etc. Put a fluke meter in any receptacle at any time in America, and you WILL measure 60hz, unless the power is going out about .5 second from when you are measuring...
Reply With Quote
  #8  
Old 03-18-2010, 10:28 AM
Andrew Mackey Andrew Mackey is offline
Sponsor
 
Join Date: Nov 2004
Location: Rockaway, New Jersey USA
Posts: 9,393
Likes: 1,197
Liked 3,871 Times in 2,497 Posts
Exclamation Re: Balancing the load - On a grand scale

Here in the US of A, most of the control is automatic. This can lead to huge headaches for the power companies, if there is a problem. A few years ago, a Solar Flare created a power surge that blew out a substation. The domino effect knocked out the entire east coast and part of Canada, before manual control stopped it. We are told it won't happen again, BUT???
Andrew
Reply With Quote
  #9  
Old 03-18-2010, 01:43 PM
m_thompson m_thompson is offline
Registered-II
 
Join Date: Dec 2006
Location: East Greenwich, RI USA
Posts: 222
Likes: 13
Liked 103 Times in 50 Posts
Default Re: Balancing the load - On a grand scale

Quote:
A few years ago, a Solar Flare created a power surge that blew out a substation. The domino effect knocked out the entire east coast and part of Canada, before manual control stopped it.
Not the entire east coast. A very sharp operator in Rhode Island saw the cascade heading east and disconnected Rhode Island from the grid. We never even saw the lights flicker.
Reply With Quote
  #10  
Old 03-18-2010, 02:46 PM
snowcountryfarmer snowcountryfarmer is offline
Registered-II
 
Join Date: Nov 2008
Location: North Country, New York
Posts: 62
Likes: 8
Liked 22 Times in 15 Posts
Default Re: Balancing the load - On a grand scale

Well...actually most of the grid in the US is somewhat automated, but is completely overseen by live operators.

Basically, large transmission and distribution systems have complex mechanisms to trip automatically, for safety reasons (mostly equipment safety, not necessarily life safety), and to protect the integrity of the grid as a whole. Breaker reclosure is automated on a very limited basis for the same reasons. When reclosing and reenergizing a city block, for example, the inrush current can be staggering, and often large customers have to manually open their load breakers and reclose them after the line voltage returns in an organized and sequential manner, to avoid tripping their utility feeder breakers.

As far as steam and gas turbines go, their warm up times are not minutes but hours, and need to be carefully brought up to temperature to avoid problems with expansion and contraction of the very large casings and shafts, among other things. Like our generators at home though, these units also have governors and can be run at varying load levels (and varying fuel consumption levels) At any given time, there are hundreds of megawatts of generation capacity, steam and gas turbines running in spinning online idle, which means they are hot, connected to the grid and running under minimal load, but ready to kick the governors if the power is needed.

I doubt very much that any operators anywhere were able to isolate their area in the northeast blackout, these things move very quickly and are hard to anticipate. The area I live in didn't have any outage during the blackout, (northern NY) but we have lots of hydro plants in the area, not a lot of population/load and presumably the protective features of the grid in the area did their jobs properly. The problem arises when an area can't disconnect itself from the grid and maintain its load through local generation. For example, if your local utility has base load of 500 MW, and only 250MW of generation, it doesn't matter if they isolate themselves or not, they simply cannot support local load with local generation.

The real root cause of the northeast blackout, was that the large loads are basically centered in the large cities (new york, boston, etc) and the generating plants that feed these areas are ohio, pennsylvania, far northern NY, canada, etc. Decentralized local generation would have certainly helped out a lot.

Another interesting thing on the horizon is actually load regulation. Try looking up 'smart grid'. Up until this point, the generators and grid are adjusted to account for the load, which is completely variable. The new idea is to send signals over the power lines to shut off your water heater, or send your washing machine or dryer a signal to run (after you load it and put it in a sort of standby mode) in the middle of the night, when the load normally drops down considerably.

Interesting stuff.
Reply With Quote
  #11  
Old 03-18-2010, 04:31 PM
Gunny Gunny is offline
Subscriber
 
Join Date: Feb 2005
Location: North Carolina
Posts: 3,165
Likes: 794
Liked 1,192 Times in 788 Posts
Default Re: Balancing the load - On a grand scale

Nice movie clip but that ain't how it works.

Mostly automated.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Onan 5.0 CCK 3CRR load balancing act Mike CCK Onan Generators 55 02-28-2010 08:08 PM
120/240 Delta Load Balancing Isaac-1 Onan Generators 2 02-21-2010 09:21 PM
Load Balancing a 120/240v genset wyM1Aguy Onan Generators 14 02-19-2010 06:20 PM
3 Phase load balancing B.Ikard Onan Generators 4 07-13-2007 08:09 AM
? Balancing Generator load Mike Vandermillen Generators & Motors General Discussion 2 08-21-2006 04:07 PM


All times are GMT -4. The time now is 08:15 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark
A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2014 by Harry Matthews
P.O. Box 5612 - Sarasota, FL 34277