First, forgive any incorrect terminology or ambiguity as I am not electrically proficient. Is it possible to have dynamic control of delivered amp load on a synchronous generator connected to an infinite grid, without varying speed of the prime mover?

In other words, if the generator is capable of delivering X amps at Y hertz; can I actively vary X amps (+or-) at Y hertz?

 

Yes.

A generator is a device for converting torque (from the prime mover) into amps. Vary the torque from the prime mover and the generator amps will vary.

The torque produced by the prime mover is a function of the energy input to the prime mover, from a fossil fuel (internal combustion engine) or a steam generator (boiler) or the wind (wind turbine) or head (hydro turbine), etc.

So, if you can have dynamic control of the energy input to the prime mover, you can have dynamic control of the amps produced by the generator which the prime mover is driving.

 

Thank you, I understand this but can I have control without adjustment to the prime mover? I want to adjust generator output at the generator.

 

First of all, when a synchronous generator is connected to an infinite grid with other synchronous generators, they are all running at a speed that directly proportional to frequency, meaning that if the grid frequency is stable, the prime mover speed is also stable. So, one doesn't change the power output of a prime mover driving a synchronous generator connected to an infinite grid by changing its speed; its speed is directly proportional to grid frequency.

A generator is a device for converting torque into amps. No torque; no amps. More torque; more amps. Less torque; less amps.

There are really only two "inputs" to a synchronous generator: torque and excitation.

Excitation of a synchronous generator has little effect on power output. Remember: Most synchronous generators operate at a fairly constant terminal voltage, meaning that the excitation is held relatively constant to do that. Since most excitation systems can only increase or decrease terminal voltage by +/- 5% or less, the effect on real power is less than +/- 5%, but the effect on apparent power is much greater, and one doesn't use excitation to control real power, only apparent power.

Only by controlling the amount of torque produced by the prime mover can one control the amount of amps produced by the generator.

Now, if you connected a variable load bank to the output of the generator in parallel with another load and you controlled the amount of power being "consumed" by the load bank while holding the prime mover torque output constant, you could control the amount of power supplying the other load. But that would be a pretty inefficient use of the prime mover and whatever is "fueling" the prime mover.

But, stranger things have happened.

 

Hi CSA & Dabears,

I think I have the same request as Dabears.

which is that my prime mover is not defined in speed and torque and I would like to be able to vary the load on the generator so that it will not bring the prime mover to a halt.

This is to be done with some micro controllers varying the generators load amp-age so that it puts less torque on the prime mover slowing it down. I know this would probably be best to stick in a fly wheel or gears but I do not have the space.

Correct me if I am wrong but by varying the generators amp load you decrease/increase the output
EG
when you decrease the load
this decreases the torque required to turn the generator over and the output of the generator in amps but not volts.

 

I believe if you disconnect two of the opposing windings then you will remove the drag when the magnet sweeps across them. So if the wind is low you could "switch" off a few pairs to limit torque, thus allowing the blade to spin. That is my theory at this point, which i am going to test in the lab eventually.

My other idea is moving the armature mechanically back and forth over the stator. As the armature "engages" more you get more torque (for higher winds/flow) and as the wind dies down you back out. So in effect your always varying the torque to match the load.

 

CSA - I would be interested in your take on my theory on how to control torque. Thanks!

 

Adam,

I don't understand the need to control torque by some means other than the prime mover governor.

I will be curious to see how you will control the emf which will be generated in the "open" windings, and how you will "close" them again.

I will also be interested to know how much energy will be required to "shift" stator windings.

But remember, I'm not about the maths.

You really need to take your discussion off-line with Phil Corso. If you send an email to him identifying yourself (as a student or an employee of some organization) you can discuss this ad infinitum. His email address is cepsicon(at)aol dot com. Just don't forget to provide "identification".

Best of luck in your endeavor.

 

CSA... thanks for the kind referral. However, I don't think I can help Dabear very much. Had you read my Armature-Reaction paper you would have known I'm not an affectionado of the torque-to-amp (and vice-versa) conversion theory.

Thanks again for remembering me!

Regards, Phil

 

Phil Corso,

I really <b>don't</b> want to start any kind of exchange On the subject, but I believe that you are the <b>only</b> person I'm aware of that thinks that torque and amps are not related.

My texts and references all relate torque and amps directly.

The formula I remember from university is:

Torque = K(sub T) * Phi(sub F) * I(sub A)

Where K(sub T)= Torque constant
Phi(sub F) = Field Flux
I(sub A) = Armature Current

The torque constant is a design characteristic of the machine, and is fixed and can't be changed. The field flux is also relatively constant for a synchronous generator (+/- 5%, usually). So, to make more amps one needs to produce more torque (for a generator). Or, to make more torque one needs to supply more amps. Since the motor is connected to the generator and the motor produces torque, then the prime mover driving the generator actually supplies the torque to the motor, via the generator and wires in the form of amps.

That's the way I was taught. That's the way it seems to work everywhere I've been or read about.

My understanding of armature reaction is very different from yours--and that's okay. Because it's not something that any operator or technician I've ever worked with or trained needed to measure or be concerned about in the execution of their job duties.

Again, we can agree to disagree or not. I just can't find any real-world texts or references that don't directly torque and amps for generators and (electric) motors.

And I can't recall a single reader of your white paper make a comment, positive or negative, on this forum about the premise you propose (right or wrong).

And you've been providing that paper for many years, as I recall.

Again, I do not want to start any manner of back-and-forth on this. I am just making a comment that you are the only individual that I'm aware of who doesn't relate torque and amps. Ever.

 

CSA... I only ask that you read the Control.Com thread, 1026236550, "The Physics of... Electrical Power!"

Phil

 

Hey, Phil,

Why don't you post your 'The Physics of....Armature Reaction!' white paper to the controlwiki?

Along with your 'Physics of... Electrical Power!' description.

Thanks!

 

> Why don't you post your 'The Physics of....Armature Reaction!' white paper to the controlwiki?

> Along with your 'Physics of...Electrical Power!' description.

Yes please. I'll be working on Controlwiki tomorrow.

Your friendly local moderator, Peg