×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Matching Voltage vs. Step

Matching Voltage vs. Step

Matching Voltage vs. Step

(OP)
Recently we have had some discussion on whether it is better to match voltage output or regulation step when tying and transferring load between substations.

It is my opinion that we should match voltage step.  This is due to the voltage at the tie point being dependant on conductor properties, distance, and load.  Without measuring the voltage at the tie point, there is no guarantee of the voltage at the tie with either method.  Essentially by matching voltage and not step, we would be connecting two transformers with different voltage outputs; the only reason that they appear to be the same is because of loading.

Due to the distance (impedance) between substations, circulating current does not appear to be an issue.  We do have some instances of two transformers in one substation.  On occasion, it is necessary to parallel these transformers.  During this situation we match the step of the regulation, due to circulating current.

I am confused as to why this would not be the best solution in all cases.  My main worry would be a younger lineman getting comfortable with matching voltage between two different substations and doing the same in the afore mentioned instance.  Any input would be greatly appreciated.

RE: Matching Voltage vs. Step

In my experience, we just made the regulator non-auto and made the tie. These transformers were all 115/12.46 kv. There was one incidence when a sub was fed from a 230/115 kv
was tied to a sub fed from a 115 kv generator and there was a reverse power flow occurred and caused some problems.

RE: Matching Voltage vs. Step

Think about what problems you are trying to avoid.  If you simply match step and you have mis-matched loads, differing transformer sizes and/or impedances or different supply voltages (transmission line source voltage at remote substations) your tie point voltage could be off significantly.  If you match secondary voltage at the substation busses regardless of vreg tap position, your tie point voltage is just a function of the feeder voltage drop which will typically be 5% or less.

In most cases, just disable the vregulation at the bus which will be losing load and let the bus which will be picking up load run on auto.  That way when the load transfers the unloaded bus voltage will rise somewhat and will stay until you return the vregs to auto however the bus which increases load will be able to automatically respond to the increased voltage drop associated with the increased load through the automatic operation of the vregs.  You don't want to create a low voltage condition during switching and have a very remote chance of causing a high-voltage condition.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources