Stator inter-turn fault detection of synchronous machines
View Patent ↗A fault detection system using field current and rotor search coil voltage harmonics is provided. The technology is capable of detecting an inter-turn fault unambiguously and rapidly in a synchronous machine. The internal asymmetry of the machine that has adversely affected the earlier fault diagnosis results has, for the first time, been shown as an advantage.
1. A method of detecting stator inter-turn faults in a synchronous machine, the method comprising:
(i) collecting at least one synchronous machine characteristic;
(ii) predicting at least one harmonic frequency for monitoring the machine based on the at least one collected machine characteristic, wherein a ratio of the at least one harmonic frequency to a line frequency is substantially equal to k/p±1, wherein k is a positive integer and p is a number of fundamental pole pairs of the synchronous machine; and
(iii) monitoring the at least one predicted harmonic frequency to determine a status of at least one stator.
2. The method of claim 1 , further comprising detecting a stator inter-turn fault based on the monitoring of the at least one predicted harmonic frequency.
3. The method of claim 2 , further comprising tripping the synchronous machine based on the detected fault.
4. The method of claim 1 , wherein the at least one harmonic frequency is predicted based on a number of fundamental poles of the synchronous machine.
5. The method of claim 1 , wherein the at least one harmonic frequency is an odd integer harmonic frequency or a fractional harmonic frequency.
6. The method of claim 1 , wherein the predicted harmonic frequency is monitored based on a current.
7. The method of claim 1 wherein the predicted harmonic frequency is monitored based on a voltage.
8. The method of claim 7 , wherein the monitoring is performed with a rotor search coil.
9. The method of claim 1 , further comprising generating a tripping signal for the synchronous machine.
10. A system for detecting a stator inter-turn fault in a synchronous machine, the system comprising:
a tunable detector configured to detect a monitor signal associated with at least a selected harmonic frequency associated with the synchronous machine, wherein a ratio of the at least one harmonic frequency to a line frequency is substantially equal to k/p±1, wherein k is a positive integer and p is a number of fundamental pole pairs of the synchronous machine; and
a signal processor configured to provide a control signal for the synchronous machine based on the monitor signal.
11. The system of claim 10 , further comprising a computer readable medium configured to store identifiers for a plurality of synchronous machine harmonic frequencies, wherein the detector is configured to receive the selected harmonic frequency based on the stored identifiers.
12. The system of claim 11 , wherein the identifiers are stored in the computer readable medium in a look-up table.
13. The system of claim 10 , wherein the signal processor is a digital signal processor.
14. The system of claim 10 , wherein the signal processor is a computer.
15. The system of claim 10 , wherein the tunable detector detects field current.
16. The system of claim 10 , wherein the tunable detector detects a rotor search coil voltage.
17. A system for detecting a stator inter-turn fault in a synchronous machine, the system comprising:
a signal processor configured to select at least one harmonic frequency associated with the synchronous machine, wherein a ratio of the least one selected harmonic frequency to a line frequency is substantially equal to equal to k/p±1, wherein k is a positive integer and p is a number of fundamental pole pairs of the synchronous machine;
a rotor search coil;
a tunable detector coupled to the rotor search coil and configured to provide a synchronous machine monitor signal to the signal processor, wherein the synchronous machine monitor signal is associated with the at least one selected harmonic frequency.
18. The system of claim 17 , wherein the signal processor is a digital signal processor.
19. The system of claim 17 , wherein the signal processor is a computer.