Generators in parallel... which supplies the current ?

Thread Starter

Externet

Joined Nov 29, 2005
1,614
Hello all.
Need to see the light, please teach me to comprehend how it works/behaves.

Two generators, their outputs paralleled feeding both the same load and perfectly synchronized; which one supplies the current to the common shared load or in what proportion do they?

240VAC60Hzgenerator1-----------------KWhmeter1-------------------LOAD--------------------KWhmeter2-----------------241VAC60Hzgenerator2

Does the amount of load has any influence ? -say 1KW- (The way the sketch above shows does not mean the load is in series)

1621594537212.png
Just an image...
 

andrewmm

Joined Feb 25, 2011
1,497
A voltage / current source, has no knowledge of the load.
The load has no knowledge if its DC or AC.

so lets simplify things, as the answer will be the same

two perfect batteries in parallel, supplying a single lamp through perfect wires.

Where does the current come from , battery left, right or both ?

Basic. think current is driven by the voltage difference, through the resistance.

The batteries provide the voltage, if both are identical voltage, and identical load, then the current flowing from both must be the same as both see the same resistance ,

In the real world that is never going to happen,
Then the battery that has the higher voltage / lower resistance to the load will supply more of the current.
( I = V/R )

In the limit, one battery will try to charge the other battery

You see in the above, there is no mention of load .
 

Thread Starter

Externet

Joined Nov 29, 2005
1,614
Thanks.
That is understandable for DC batteries, devices that deplete their amount of charge and internal resistance. What about AC generators, where their fixed voltage outputted is as shown ?
 

Ramussons

Joined May 3, 2013
984
Thanks.
That is understandable for DC batteries, devices that deplete their amount of charge and internal resistance. What about AC generators, where their fixed voltage outputted is as shown ?
In case of AC, the Internal Impedence of the generators and the purity of the generated sine wave (Harmonic content) will determine the current in each. In addition, there could also be an internal circulating current that oscillates between the 2 generators.
 
When you talk about DC power supplies in a master/slave arrangement, the supplies are identical in voltage, current capabilities.

One is configured as a voltage source slightly less than the desired value with the current limit at half the measured current.

The other is configured as a current source with a slight overvoltage (the desired output).

With an AC generator, I think you have to look at it as a grid-tie inverter. It will try to supply current up until it's current limit until the voltage goes out of tolerence or it loses sync.
 

ronsimpson

Joined Oct 7, 2019
1,243
240VAC60Hzgenerator1-----------------KWhmeter1-------------------LOAD--------------------KWhmeter2-----------------241VAC60Hzgenerator2
If the wires have zero resistance then the 241V source should pick up the load. But.....
The wires do have resistance so .... 241V at the generator2 but because of the loss in the wire maybe there is only 240 at the load. Now generaor1 sees the load and can send some power.
In a real system there large system there are many generators and many loads all working and the wire resistance and helps the generators share. Also there is a load to voltage curve on the generator. Likely a heavily load generator will supply only 235V and a lightly load generator will supply 245V. That will help share the load. So in our example (Generator2 + wire) will load down until Generator will pick up part of the load.
 

schmitt trigger

Joined Jul 12, 2010
442
In practice, the generator’s field current is adjusted to ensure that each individual generator is sharing the load correctly.
To rely solely on impedance wouldn’t achieve this condition.

YouTube has many videos of utilities paralleling generators to the main grid, which could have already a hundred generators interconnected.
 
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