Failure to control Excitation

[adyeeri]

Hi all,

I'm new to this forum and seek your technical/operational opinions. I supervise the operations and maintenance of a mini hydro power plant with three identical synchronous generators 3889KVA, 6600V, 340A in western Uganda. We have excitation control problems where we can't induce external excitation because on the turn of the knob (raise/lower), the reactive power erratically swings between lead/lag and the generator(s) decouple. This is a problem on two of the units and the third is doing well. Thanks

 

[waross]

It is normal for over excitation or under excitation to cause reactive current flow. If the generator is unloaded or lightly loaded, a small change in excitation may cause a relatively large change in reactive current or power. Adjust for minimum reactive current and put some load on the generator and try again.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[crshears]

What Bill said, plus...

Is this a new plant or an existing one?

Has there been any construction work going on within the plant or in close proximity to it? If so are the two misbehaving units by chance the ones closest to the work? I have seen that type of temperamental excitation control arise due to grit on the rheostat faces causing erratic non-linear ohmic values.

There could of course be other causes...

Oh yeah! Should have said, "Welcome to the forums!"

Also, just for next time, this post appears better suited to the "Electric Motors & Generators Engineering" forum than this one - - but not to worry, no need to re-post as a bunch of us follow this forum as well as that one.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]