Capacitor placement problem
Capacitor placement problem
(OP)
Our system is approximately 60% underground. It's a 12.47 kV system. The problem is the placement of capacitor banks. Since our system is underground, Ferro-resonance is a problem. Capacitive more than inductive in our system. We need to correct power factor, but is very difficult to say the least. Has anyone dealt with this type problem and come up with a successful solution?






RE: Capacitor placement problem
Ferro-resonance can be avoided by adjusting the reactances, ensuring 3 phase switching (avoiding single phasing), keeping some load, etc.
RE: Capacitor placement problem
RE: Capacitor placement problem
What type and size of caps you added? What do you mean no room in side the switchgear? Any MV capacitors will be in its own enclosure and most likely fed by a separate breaker and controls. Not sure what is attempted in your case.
RE: Capacitor placement problem
RE: Capacitor placement problem
You should also be able to install caps at service points to major customers that have three-phase switching.
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: Capacitor placement problem
We have the vast majority of capacitor banks located within our substations. Wanted to improve at the delivery point. Plus reduce purchased power penalties. That's why I am looking at small units only. Say 3-100- 3-150 KVAR units. Measuring PF at station. This could be 1000' to 2.5 miles away from delivery point.
Thanks for your assistance.
RE: Capacitor placement problem
You can do that, but then you will have to reduce equivalent caps at the substations. Substations caps are adequate for reducing penalty, adding more caps at the load will not help.
Perceived reduction is copper losses are usually negligible. Why do you want to do that? Is there a benefit?
RE: Capacitor placement problem
What everyone has been trying to pull out of you is more details, like
- what is the present load at the substation (kW and kvar)
- what is the load at light load conditions
- substation transformer MVA rating
- substation capacitor bank rating(s)
- what does the existing voltage profile look like
- what would it look like with more capacitors along the line
- what power factor would you want
It may very well be that the substation capacitor banks is the best you can possibly do for the circuit. I can't really tell from what has been provided so far.
The ferroresonant circuit is mainly initiated by single-phase switching. Eliminate that and you virtually elliminate ferroresonance.
Would like to help further, but need a lot more input.
RE: Capacitor placement problem
RE: Capacitor placement problem
If you have a system such as this, then you need to get the line analyisis software and start modeling.
JIM
RE: Capacitor placement problem