reverse power flow

[powerman123]

Hi guys,

I am struggling with this question. Help would be really appreciated.

'A generating plant is connected to the 11 kV network. If it produces 8 MW operating at 0.88 lagging factor, calculate the reverse power flow into the transmission network during the peak loading conditions and estimate the corresponding per-unit voltage at the 11 kV busbar.'

Thanks

powerman123

 

[ScottyUK]

The question appears to be incomplete. Is there an accompanying diagram?

Did you read the rules about posting homework questions?

 

[odlanor]

prime mover basic characteristics must be provided firstly, not generator.

 

[odlanor]

prime mover basic characteristics must be provided firstly, not generator.
reverse power flow from transmission network into generating plant. You must worry about prime mover.

 

[powerman123]

Im sorry, you are right. I have missed a section out. Here is the whole question:

'A factory is supplied over a 33 kV 3-phase transmission line. The line is 20 km long, has an impedance of (0.05 + j0.5) ohms/km and connects to the local distribution network by a transformer rated 10 MVA, 33 kV/11 kV. The transformer reactance, expressed to its own base, is 0.06 pu. Peak demand at the receiving end of the line draws a total (apparent) power of 8 MVA at 0.92 lagging power factor into the sending end of the line. If the voltage at the sending end is 1.0 pu:

1) calculate the voltage at the receiving end using a 10 MVA base for per-unit calculation.

2) suggest a tap-setting for the transformer to bring the on-load voltage during the peak demand close to 1.0 pu.

3) A generating plant is connected to the 11 kV network. If it produces 8 MW operating at 0.88 lagging factor, calculate the reverse power flow into the transmission network during the peak loading conditions and estimate the corresponding per-unit voltage at the 11 kV busbar'

thanks again

powerman123

 

[powerman123]

Hi ScottyUK, it isnt a homework question, its a past paper question. Thanks for the help

 

[davidbeach]

What's you're work on it to this point?

 

[ijl]

The problem is an unconventional load flow-problem: Power and power factor of the generator are given, but not the voltage.
Hints for solving:
Unknowns: The current from the generator, the current to the load, and the voltage at the 11kV bus, all as complex variables. Three equations needed: Apparent power from the generator (S = UI*), apparent power to the load, and the voltage difference ("drop") from 11kV bus to 33kV bus (Ohms law). The 33kV is assumed to be fixed. My results in the attachment (no guarantee for correctnes

 

[meeko]

so did you find your answer? id be curious to see your work on this, as i can learn from it aswell