Power Frequency Variations
Power Frequency Variations
(OP)
An electrical governing body in our location is recommending to increase the normal operating system frequency limit from +/- 0.3 Hz to +/- 0.5 Hz. This means that the generators will need to operate normally between 59.5 to 60.5 Hz and the System Operator will not intervene if the system frequency is within these limits.
If the recommendation is approved, it will be implemented as a grid frequency variation limits requirement.
In this regard, i would like to solicit your comments regarding the impact on the existing machines. As I understand, NEMA motors may run within +/-5% at rated voltage.
Furthermore, are there supposed to be a steady state frequency and transient state frequency limits?
Any technical links that would be of reference will be appreciated.
If the recommendation is approved, it will be implemented as a grid frequency variation limits requirement.
In this regard, i would like to solicit your comments regarding the impact on the existing machines. As I understand, NEMA motors may run within +/-5% at rated voltage.
Furthermore, are there supposed to be a steady state frequency and transient state frequency limits?
Any technical links that would be of reference will be appreciated.
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata






RE: Power Frequency Variations
RE: Power Frequency Variations
RE: Power Frequency Variations
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Power Frequency Variations
I agree with gepman, at plus/minus 0.5 Hz, the biggest concern would be under/over frequency relays and maybe governor settings, if you have anything running isochronous.
I suppose any highly speed-sensitive machines running from synchronous motors could be a concern as well.
RE: Power Frequency Variations
RE: Power Frequency Variations
RE: Power Frequency Variations
The clocks will all be flashing to indicate a power failure and will be reset when the normal power returns.
In conclusion I don't see a potential problem with connected equipment with an increase to +/- 0.5 Hz variation in frequency.
As for clocks, the present 0.3 Hz variation would result in a clock error of over 7 minutes a day, so I imagine that whatever system is presently used to balance over frequency against under frequency will continue to function with the new standard.
In the old days, of flyball governors, the word would be,
"We are quite a few cycles behind today. We are running "Balls to the walls" until we catch up."
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Power Frequency Variations
RE: Power Frequency Variations
RE: Power Frequency Variations
Seems like you are widened the band for frequency contribution, which will allow poor regulation machines to contribute to the system, in some cases the problem is also time response not just wide the freq band, as you said wind power plants could be the reason, it would required as already said review the adjustments for under/over frequency relays.
RE: Power Frequency Variations
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata
RE: Power Frequency Variations