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#1

# Voltage and frequency in finite bus

what happens to the voltage and frequency in a finite bus when there is a new load connected or a previous load has been removed..?
08-25-2013 11:19 PM
Top #2
That all depends on the characteristics of the bus and on the load.
08-25-2013 11:19 PM
Top #3
I agree... It depends on the behavior of the feeder/ load (to be removed or to be added)... there would be some transient dips or sags (depending on pick-up time of the generators)... we do have some problems on power transients, as load-side in the industry, since we have synchronous motors that are sensitive to phase, voltage and frequency variations...
08-25-2013 11:20 PM
Top #4
Infinite, Nothing.

but let me record that if a significant load is added to a bus (fed by genset(s)), Droop will take place. voltage and frequency will drop down for a while. Governer & AVR will bring the set to stabilization withing the required time.Increase in voltage & frequency will be noticed upon removal of a significant load and similiary governer/AVR will adjust the system as necessary.
08-26-2013 09:40 PM
Top #5
Simplest way to understand how voltage and frequency reacts to any addition of load or reduction of load to the system, which could answer also how under & over frequency happens, is like cycling a bicycle.

So reduction of load is vice versa. By understanding this simple concept, i believe you can know yourself what will happen when there is a new load connected or a previous load has been removed.

08-26-2013 09:40 PM
Top #6
As per the original question: In a finite bus, as Ole and Lester says.

And additional issue is to define: what is a finite bus?

Some engineers normally assumes that when a generator has a capacity of greater than 5% of the system size, then with respect to this generator, the system does not behave as an infinite bus.

For example, when an 800 MW generator is loaded onto a grid having a capacity of l0,000 MW, the system voltage and frequency can vary and the system will behave as a non-infinite bus.
08-27-2013 08:58 PM
Top #7
When a new load is connected to a finite bus, the voltage and frequency reduces.
while a reduction in load increases the frequency and voltage.
These changes (frequency and voltage) may be noticeable or not so noticeable depending on the size of the power grid network.
08-27-2013 08:58 PM
Top #8
>>what happens to the voltage and frequency in a FINITE bus when there is a new load connected or a previous load has been removed<<

Simple analogy; Adding or removing load from a mule. If the system, (i.e. the mule) can handle it, both freq. and voltage will either decrease or increase depending upon the size of the load involved.
08-27-2013 08:58 PM
Top #9
@Bill: Or the voltage and/or the voltage might increase, if we apply the right type of load. Remember, the mule could be pulling a cart, on the way down a steep slope!