S
Dear all,
In case of a grid failure large generators are often obliged to be keep connected to the grid in order to help stabilizing it. The "low voltage ride through" or "fault ride through" curve defines how long a generator has to keep connected to the grid depending on the actual grid voltage during failure.
I have often read that synchronous generators get into trouble during a failure since the mechanical power seen by the generator is greater than the electrical power the generator delivers to the grid. This leads to an acceleration of the rotor angle and finally can lead to instability if the angle is getting greater than pi/2.
Now I don't understand why the electrical power the generator delivers to the grid gets smaller during failure. How does this correlate to the grid voltage (which is very low at the time)? Is the reason the lacking power supply of excitation system by the net? And what are the governing equations which can describe the effect?
Further I've read that the stability is not only influenced by the time the generator has to stay connected after failure (fault clearance time), but as well by the generator's pre-fault operating point in terms of apparent power and voltage. Maybe you could also elaborate on these dependencies.
I would be very thankful if you have any knowledge about this and if you could also suggest further literature for this problem.
Cheers,
krigl
In case of a grid failure large generators are often obliged to be keep connected to the grid in order to help stabilizing it. The "low voltage ride through" or "fault ride through" curve defines how long a generator has to keep connected to the grid depending on the actual grid voltage during failure.
I have often read that synchronous generators get into trouble during a failure since the mechanical power seen by the generator is greater than the electrical power the generator delivers to the grid. This leads to an acceleration of the rotor angle and finally can lead to instability if the angle is getting greater than pi/2.
Now I don't understand why the electrical power the generator delivers to the grid gets smaller during failure. How does this correlate to the grid voltage (which is very low at the time)? Is the reason the lacking power supply of excitation system by the net? And what are the governing equations which can describe the effect?
Further I've read that the stability is not only influenced by the time the generator has to stay connected after failure (fault clearance time), but as well by the generator's pre-fault operating point in terms of apparent power and voltage. Maybe you could also elaborate on these dependencies.
I would be very thankful if you have any knowledge about this and if you could also suggest further literature for this problem.
Cheers,
krigl