Electric power control system and efficiency optimization process for polyphase synchronous machine

1. A method comprising:

determining an applied armature voltage supplied to a polyphase synchronous machine having a pull-out torque, the armature voltage supplied from a power source via one of a plurality of taps of a regulating transformer, a first tap of the plurality of taps configured to supply a voltage at a different level than a second tap of the plurality of taps;

selecting the second tap to supply the armature voltage based on the determined applied armature voltage, power consumption of the machine, and a confidence level that the pull-out torque is not exceeded, wherein the confidence level corresponds to a probability distribution indicative of at least one operating characteristic of the polyphase synchronous machine; and

responsive to a slip of the polyphase synchronous machine, increasing a margin of the pull-out torque.

2. The method of claim 1 , further comprising:

continuously determining the applied armature voltage supplied to the polyphase synchronous machine.

3. The method of claim 1 , wherein the selected confidence level is applied to a statistic of the time varying mechanical load applied to the polyphase synchronous machine.

4. The method of claim 1 , further comprising:

determining a slip of the polyphase synchronous machine.

5. The method of claim 1 , further comprising:

determining a mechanical torque demand; and

comparing the mechanical torque demand against a predetermined torque.

6. The method of claim 5 , further comprising:

determining an optimum armature voltage level corresponding to the predetermined torque.

7. The method of claim 5 , wherein determining the mechanical torque demand is based on a measurement of the machine actual load.

8. The method of claim 7 , further comprising:

determining the maximum mechanical torque demand in real time.

9. The method of claim 1 , further comprising:

setting the armature voltage to be supplied to the machine to cause the pull-out torque of the machine to be greater than a maximum mechanical torque demand.

10. The method of claim 1 , further comprising:

specifying a margin of the pull-out torque with an upper and a lower bound to decrease a frequency of armature voltage changes.

11. The method of claim 1 , wherein the selecting the second tap comprises:

determining a suitably smooth estimate of the mechanical load torque using a real power demand signal observed at armature terminals of the polyphase synchronous machine;

determining a pull-out torque of the machine using physical parameters of the polyphase synchronous machine, a real and reactive power observed at the armature terminals, and the applied armature voltage; and

comparing a difference in the mechanical load torque and the pull-out torque against a pre-defined margin boundary.

12. A method comprising:

receiving, by a voltage signal processor, an indication of an armature voltage, real power and reactive power monitored at an armature of a synchronous machine;

determining a characteristic of the synchronous machine based on the received indication, the characteristic comprising a maximum mechanical torque demand; and

adjusting, based on the determined characteristic and a confidence level that a pull-out torque of the synchronous machine will not be exceeded, the armature voltage supplied to the synchronous machine.

13. The method of claim 12 , wherein the characteristic comprises a slip of the synchronous machine.

14. The method of claim 13 , further comprising:

responsive to determining the slip of the synchronous machine, increasing a margin of a pull-out torque.

15. The method of claim 12 , further comprising:

specifying a margin of the pull-out torque with an upper and a lower bound to decrease a frequency of armature voltage changes.

16. The method of claim 12 , further comprising:

determining a suitably smooth estimate of a mechanical load torque using a real power demand signal monitored at the armature of the synchronous machine;

determining an estimated pull-out torque of the machine using physical parameters of the synchronous machine, the real and reactive power monitored at the armature, and the applied armature voltage; and

comparing a difference in the estimate of the mechanical load torque and the estimated pull-out torque against a pre-defined margin boundary.

17. The method of claim 12 , further comprising:

adjusting the armature voltage to be supplied to the machine to cause a pull-out torque of the machine is greater than a maximum mechanical torque demand.

18. The method of claim 12 , wherein adjusting the armature voltage further comprises:

selecting a first tap of a regulating transformer supplying power from a power source.

19. The method of claim 18 , further comprising:

selecting a second tap of the regulating transformer, the second tap configured to supply voltage at a different level than the first tap.

20. The method of claim 12 , further comprising:

determining the characteristic based on a measurement of the machine actual mechanical load torque.