Method For Detecting A Fault Condition In An Electrical Machine

• US 20150276823A1
• Filed: 10/03/2013
• Published: 10/01/2015
• Est. Priority Date: 11/01/2012
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Rodriguez, Pedro, Pinto, Cajetan, Orman, Maciej, Orkisz, Michal, Disselnktter, Rolf, Ahrend, Ulf, Rzeszucinski, Pawel, Ottewill, James
• Granted Patent: US 10,088,506 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 19/02 Measuring effective values, i.e. root-mean-square values
• CPC Class Codes: G01R 23/00 Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/346 Testing of armature or field windings

Abstract

A method for identifying a fault condition in an electrical machine in which at least a stator or a rotor has parallel winding branches is disclosed. A measurement is carried out for obtaining a set of circulating current values between two parallel winding branches of which each winding branch includes a single coil. A frequency analysis is applied on the set of circulating current values to obtain at least one frequency component. A fault condition of the electrical machine is determined on the basis of the at least one frequency component.

Claims

1. A method for identifying a fault condition in an electrical machine in which at least a stator (120) or a rotor (220) has parallel winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180), the method comprising the steps of:

carrying out a first measurement (230) for obtaining a first set of circulating current values (240) between two parallel winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180) of which each winding branch (30, 40, 50, 60, 130, 140, 150, 160, 170, 180) comprises a single coil (20);

applying a frequency analysis (250) on the first set of circulating current values (240) to obtain at least one frequency component (260); and

determining, on the basis of the at least one frequency component (260), a fault condition (280) of the electrical machine.

2. A method according to claim 1, wherein the fault condition is one of the following:

dynamic eccentricity, static eccentricity, inter-turn short circuit in the rotor (220), inter-turn short circuit in the stator (120).

3. A method according to any of the preceding claims, wherein the method comprises the step of:

determining, on the basis that the at least one frequency component has a value (2k+1)f_s±

f_r, wherein k=(0,1,2,3, . . . ), f_s=supply frequency and f_r=rotational frequency of the electrical machine, that the machine suffers from dynamic eccentricity.

4. A method according to any of the preceding claims, wherein the method comprises the step of:

determining, on the basis that the at least one frequency component has a value kf_s, wherein k=(1,2,3, . . . ) and f_s=supply frequency, that the machine suffers from static eccentricity.

5. A method according to any of the preceding claims, wherein the method comprises the step of:

determining, on the basis that the at least one frequency component has a value kf_r, wherein k=(1,2,3, . . . ) and f_r=rotational frequency of the electrical machine, that the machine suffers from inter-turn short circuit in the rotor (220).

6. A method according to any of the preceding claims, wherein the method comprises the step of:

determining, on the basis that the at least one frequency component has a value (2k+1)f_s, wherein k=(0,1,2,3, . . . ) and f_s=supply frequency, that the machine suffers from inter-turn short circuit in the stator (120).

7. A method according to any of the preceding claims, wherein the electrical machine is a synchronous electrical motor or generator.

8. A method according to any of the preceding claims, wherein the first measurement (230) is carried out with two current sensors for obtaining branch current signals from the two parallel winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180), and wherein the first set of circulating current values (240) is deduced from the branch current signals using an operational amplifier or using a numerical subtraction after the branch current signals have been converted into a digital domain.

9. A method according to any of claims 1-7, wherein the first measurement (230) is carried out with a differential current sensor (110).

10. A method according to claim 9, wherein the first measurement (230) is carried out between two opposite winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180) in circumferential direction of the stator (120).

11. A method according to any of the preceding claims, wherein the method comprises the step of:

carrying out a second measurement (230) corresponding to the first measurement (230), the two parallel winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180) in the second measurement (230) being different from those in the first measurement (230).

12. A method according to claim 11, wherein the two parallel winding branches (30, 40, 50, 60, 130, 140, 150, 160, 170, 180) in the second measurement (230) are in a different electrical phase (I, II, III) than those in the first measurement (230).

13. A method according to any of the preceding claims, wherein the method comprises the step of:

carrying out a measurement (230) corresponding to the first measurement (230) for winding branches in each electrical phase (I, II, III) of the electrical machine.

14. A method according to any of the preceding claims, wherein a fault condition (280) of the electrical machine is determined on the basis of more than one frequency components (260).

15. A method according to any of the preceding claims, wherein the method comprises the step of:

comparing an amplitude of the circulating current (85) at the frequency component (260) with a predetermined threshold value.

16. A method according to any of the preceding claims, wherein the method comprises the step of:

comparing a relative amplitude of the circulating current (85) at the frequency component (260) with a predetermined threshold value, wherein the relative amplitude is determined by an algorithm comprising a root mean square of the circulating current (85) at the frequency component.

17. A method according to any of the preceding claims, wherein the method comprises the step of:

comparing a relative amplitude of the circulating current (85) at the frequency component (260) with a predetermined threshold value, wherein the relative amplitude is determined by an algorithm comprising a factor

18. A method according to any of the preceding claims, wherein the method comprises the step of:

comparing a relative amplitude of the circulating current (85) at the frequency component (260) with a predetermined threshold value, wherein the relative amplitude is determined by an algorithm

19. A method according to any of the preceding claims, wherein the first measurement (230) is carried out during a transient operation of the electrical machine.