Stator inter-turn fault detection of synchronous machines

• US 7,592,772 B2
• Filed: 10/08/2007
• Issued: 09/22/2009
• Est. Priority Date: 10/08/2007
• Status: Expired due to Fees

• Current Assignee: University of Victoria Innovation and Development Corporation
• Original Assignee: University of Victoria Innovation and Development Corporation
• Inventors: Neti, Prabhakar, Nandi, Subhasis
• Primary Examiner(s): Ro; Bentsu
• Assistant Examiner(s): Paul; Antony M
• Application Number:
  US11/868,934
• Publication Number:
  US 20090091289A1
• Time in Patent Office: 715 Days
• Field of Search: 361/30, 324/772, 324/545, 340/648, 318/798, 318/803, 318/806, 318/565, 318/629, 318/690, 318/705, 318/773, 318/807, 318/822, 318/244
• US Class Current: 318/798
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage

Abstract

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.

Claims

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.