I am wondering if any potential damage or fault can be caused by low-frequency electrical resonance/oscillation in a power grid/system due to its internal & external/parasitic inductive and capacitive components.

If so, what are some good examples to prove and show this point?

We know at the resonant frequency, a system can output much higher output in magnitude which might exceed the power rating of the circuit, which can potentially damage the circuit or the load that's connected to the circuit. I am wondering if this situation can be applied to power systems/grids, more specifically in the low-frequency range, like 1Hz to 20Hz.

Many thanks in advance!

  • \$\begingroup\$ Not sure about resonance, but definitely systems involving motors and machinery cause stuff on the grid, sometimes damaging equipment. The funny thing is that you can rarely prove that your TV was damaged by a compressor that your neighbor just tried to use. \$\endgroup\$ – Gregory Kornblum Feb 1 '17 at 8:59
  • \$\begingroup\$ If you are talking about 1 Hz to 20 Hz then why would anything electrically resonate given that the lowest common frequency used is 50 Hz. \$\endgroup\$ – Andy aka Feb 1 '17 at 9:08
  • \$\begingroup\$ @Andyaka there's nothing to worry about during normal operation, my question is to ask if there's a situation that the operating frequency would drop to a very low range and triggers low-frequency resonance that can potentially cause faults \$\endgroup\$ – Andy Wang Feb 1 '17 at 9:34
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    \$\begingroup\$ @Andyaka The primary grid freq based power production control has inherent delays and overshooting behaviour. You can make the grid, at least locally, oscillate (think of it like this: grid frequency lower than nominal 50 Hz; generators A&B hence are fed more mechanical power; since A has less mass, it spins up faster; 50 Hz is reached while B is still under increasing torque. The system overshoots to > 50 Hz. Repeat that in the other direction, and consider non-zero loop delay.) \$\endgroup\$ – Marcus Müller Feb 1 '17 at 10:24
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    \$\begingroup\$ @Andyaka yeah... 0.4 grid frequency... no. \$\endgroup\$ – Marcus Müller Feb 1 '17 at 10:34

Long story short:

Grid frequency is what is used by the power companies to adjust the energy production. A generator under heavy load turns slower, and you can counter that by applying more mechanical power to it.

This primary control scheme really isn't instantaneous and perfectly easy to apply. That means that within the European grid, you'll often see sudden load changes (or sudden production changes, e.g. from a nuclear plant suddenly dropping out of the net) "ripple" through the grid, get overcompensated, then oscillate back.

If you understand German or feel OK with an English synchro track also available there: there was a rather entertaining more than technically detailed talk on that topic at 32c3. The idea was that it's not that hard (not that easy, either) to fabricate cases where elegantly placed sudden changes to the grid constructively overlay their effects in a manner that makes power grids fail. And what I took away from it: an emergency shutdown of a large power plant is less bad than what happens every 15 minutes synchronously due to the fact that electrical energy production of brokered in quarter hour packets

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  • \$\begingroup\$ thanks for the answer and your time, however, to me, your answer didn't address my question regarding low-frequency resonance in the grid; Please let me know if I am missing something. \$\endgroup\$ – Andy Wang Feb 1 '17 at 9:40
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    \$\begingroup\$ what is an amplitude-increasing oscillation fed by resonant behaviour other than a resonance? \$\endgroup\$ – Marcus Müller Feb 1 '17 at 10:21
  • \$\begingroup\$ @MarcusMüller I think Andy is looking for resonances caused by the inherent electrical behaviour of the grid itself, not by the control systems attached to the grid. Though those are also interesting! \$\endgroup\$ – user253751 Oct 29 '19 at 15:11

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