Method for monitoring demagnetization

• US 9,823,308 B2
• Filed: 10/29/2013
• Issued: 11/21/2017
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Schweiz AG (ABB Limited)
• Inventors: Rodriguez, Pedro
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): Nasir, Taqi
• Application Number:
  US14/066,307
• Publication Number:
  US 20140049285A1
• Time in Patent Office: 1,484 Days
• Field of Search: 32476501, 324701, 324623, 324200-20726, 324209-263, 318480, 31840033, 31840021, 318701, 318490, 31015643, 310268
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36

Abstract

A method for discovering demagnetisation faults of a permanent magnet synchronous generator, such as a wind power generator. The method is performed during operation of the synchronous generator and includes measuring the vibration of the stator, performing a frequency analysis of the vibration, and deducing whether the generator suffers from demagnetization of a permanent magnet, from the vibration analysis. Moreover, geometric eccentricity faults and electric short circuit faults may also be detected from the vibration.

Claims

1. A method for monitoring demagnetization of permanent magnets in a synchronous machine, such as a wind power generator, having a stator with windings and a rotor with permanent magnets being arranged to rotate in relation to the stator, the method being performed during operation of the synchronous machine, and the method including the steps of:

measuring with a vibration sensor the vibration of the stator,

performing with an analyzer a frequency analysis of the vibration,

determining with an identifier, on the basis of whether the magnitude of the vibration at the supply frequency of the stator exceeds a threshold value or not, whether the machine suffers from demagnetization of a permanent magnet or not.

2. The method according to claim 1, wherein the method further comprises the step of:

determining, on the basis of whether the magnitude of the vibration at the rotation frequency exceeds a threshold value or not, whether the machine suffers from demagnetization of a permanent magnet or not.

3. The method according to claim 1, wherein the vibration measurement includes detecting vibrations by means of a vibration sensor that is fixed to a frame of the stator or fixed to the stator.

4. The method according to claim 1, wherein the machine is a permanent magnet synchronous generator.

5. The method according to claim 1, wherein the vibration measurement includes detecting vibrations with an accelerometer.

6. The method according to claim 1, wherein the method is implemented in a control system of a wind power plant.

7. The method according to claim 1, further comprising the step of presenting an alarm indicating a fault.

8. The method according to claim 1, wherein the step of determining includes analyzing reference data including magnitude levels corresponding to levels of demagnetization.

17. The method according to claim 1, wherein the step of determining comprises determining demagnetization from vibrations alone.

18. The method according to claim 8, wherein the reference data is created by measuring operation using a permanent magnet that is less strong than a nominal magnetic strength normally used.

9. A system for monitoring demagnetization of permanent magnets in a synchronous machine having a stator with windings and a rotor with permanent magnets being arranged to rotate in relation to the stator, comprising:

a vibration sensor measuring vibration of the stator,

an analyzer performing a frequency analysis of the vibration,

an identifier determining, on the basis of whether the magnitude of the vibration at the supply frequency of the stator exceeds a threshold value or not, whether the machine suffers from demagnetization of a permanent magnet or not.

10. The system according to claim 9, further comprising a memory having reference data including magnitude levels corresponding to levels of demagnetization.

11. The system according to claim 9, wherein the identifier confirms a fault indication on the basis of whether the magnitude of the vibration at the rotation frequency exceeds a threshold value or not.

12. The system according to claim 9, further comprising a display displaying an indication of a fault.

13. The system according to claim 9, wherein the machine comprises a permanent magnet synchronous generator.

14. The system according to claim 9, wherein the vibration sensor comprises an accelerometer.

15. The system according to claim 9, wherein the analyzer is integrated into portable control equipment.

16. The system according to claim 9, wherein the analyzer is integrated into in a control system of a wind power plant.