Voltage rise on transmission lines
Voltage rise on transmission lines
(OP)
Adding capacitance to a transmission line will cause the line voltage to rise.
For a given capacitance and a given transmission line, will adding significant inductance in series with the capacitor reduce the voltage rise? i.e. series resonant between 3rd and fourth harmonics.
Best regards,
Mark
For a given capacitance and a given transmission line, will adding significant inductance in series with the capacitor reduce the voltage rise? i.e. series resonant between 3rd and fourth harmonics.
Best regards,
Mark
Mark Empson
Advanced Motor Control Ltd






RE: Voltage rise on transmission lines
Too much capacitive charging current on 230kv lines and higher are normally mitigated by shunt reactors during lightly loaded conditions, which may be switched out during periods of heavy loading and also when voltage levels are low.
RE: Voltage rise on transmission lines
RE: Voltage rise on transmission lines
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Voltage rise on transmission lines
RE: Voltage rise on transmission lines
If there are only two circuits tying together portions of a system, fair enough; but there are situations where the loss of the remaining 500 kV circuit simply 'downloads' the transfer onto the 230 kV network below it. If in this instance the system operator is desperate enough to get rid of all those unwanted VARs they will, with discretion, configure the balance of the system for this recognized contingency and live with the risk.
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Voltage rise on transmission lines
Adding more load is real solution/or alternatively disconnecting it.
Example of island operation, (from my head, not calculated):
120kV transmission: Generator 20kV -> 18KV, plus tap changer on 120kV transformer can further turn it down; goal reaching 120-5%kV at the delivery transformer.
Once you reach this point, you capacitive power will linearly be lower than what you would expect at full 120kV sending (and maybe 130kV at the receiving end).
RE: Voltage rise on transmission lines
RE: Voltage rise on transmission lines
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Voltage rise on transmission lines
I don't know who in Ontario after the deregulation still seriously do the transmisison planning work. Sorry to ask but Do your company still have transmission planning department or within IESO? I heard that Hydro one only hires outsiders to do the T planning work. Best Wishes with the parallel operations.
RE: Voltage rise on transmission lines
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Voltage rise on transmission lines
RE: Voltage rise on transmission lines
Maybe it is better to say the tools aren't perfect, but they do calculate single, double, and all manner of other contingencies, and as such don't leave much ground uncovered.
That being said, the Blackout of 2003 was 'the perfect storm,' and as such was one of those scenarios that defies the ability of any predictive analysis tool since that concatenation of circumstances was 'beyond the normal scope of coverage' [one of those phrases that says a lot less than it seems to, similarly to 'the system functioned as designed,' one of my personal favorites].
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]