Hi Forum, I seek your help.
when a synchronous generator is running on a large grid, How does the increase of water flow/push onto the turbine translate into stator current increase? (assuming generator producing positive vars, exciter remains constant)
Thank you for your kindness of helping or intention to help, however, I am not looking for answers from "conservation of energy" point of view, I am not looking for a "phasor diagram" explanation either. I my opinion, those are very good explanations to explain the end result: voltage induced by flux of rotor alone (most literatures refer to that voltage as Ea) will lead output voltage even more (torque angle has increased), Var will decrease a bit, output power will increase as the portion of amp that is in phase with output voltage has increased.
My real puzzle is: with excitation be constant, speed of the rotor constant, you will have a constant induced voltage on stator. which may lead or lag, but nonetheless constant in value. what caused the current in stator to start to increase?
My guess is that: at the transient of increasing water flow onto the turbine, rotor actually speeds up a bit, and Ea increases in magnitude (so that means governor sometimes DOES have an effect on the voltage and vars when on the grid). The increase of magnitude of Ea will cause current in the stator to increase, which causes more magnetic counter torque, which will slow down the the "rotor speeding up", reducing the torque angle between rotor flux and stator flux, thus increaseing the counter torque even more. And eventually rotor will come back to synchronous speed ending up with the same speed and same Ea (the magnitude of which is again solely determined by the excitor).
assuming no wire will burn no matter the current, also assuming all iron cores are ideal (meaning no matter how fast your flux can change, the same proportion of voltage can be induced on the stator, and the same proportion of current will be flowing in the stator as well) : hyperthetically, no matter how huge the sudden increase of water will be, rotor will NEVER EVER fly out of control at the transient. because the change of amp's phase angle is always bigger than Ea's phase angle, so the counter torque will always compenstate the torque from water.
when a synchronous generator is running on a large grid, How does the increase of water flow/push onto the turbine translate into stator current increase? (assuming generator producing positive vars, exciter remains constant)
Thank you for your kindness of helping or intention to help, however, I am not looking for answers from "conservation of energy" point of view, I am not looking for a "phasor diagram" explanation either. I my opinion, those are very good explanations to explain the end result: voltage induced by flux of rotor alone (most literatures refer to that voltage as Ea) will lead output voltage even more (torque angle has increased), Var will decrease a bit, output power will increase as the portion of amp that is in phase with output voltage has increased.
My real puzzle is: with excitation be constant, speed of the rotor constant, you will have a constant induced voltage on stator. which may lead or lag, but nonetheless constant in value. what caused the current in stator to start to increase?
My guess is that: at the transient of increasing water flow onto the turbine, rotor actually speeds up a bit, and Ea increases in magnitude (so that means governor sometimes DOES have an effect on the voltage and vars when on the grid). The increase of magnitude of Ea will cause current in the stator to increase, which causes more magnetic counter torque, which will slow down the the "rotor speeding up", reducing the torque angle between rotor flux and stator flux, thus increaseing the counter torque even more. And eventually rotor will come back to synchronous speed ending up with the same speed and same Ea (the magnitude of which is again solely determined by the excitor).
assuming no wire will burn no matter the current, also assuming all iron cores are ideal (meaning no matter how fast your flux can change, the same proportion of voltage can be induced on the stator, and the same proportion of current will be flowing in the stator as well) : hyperthetically, no matter how huge the sudden increase of water will be, rotor will NEVER EVER fly out of control at the transient. because the change of amp's phase angle is always bigger than Ea's phase angle, so the counter torque will always compenstate the torque from water.
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