Synchronous compensation

• US 6,737,767 B2
• Filed: 01/24/2003
• Issued: 05/18/2004
• Est. Priority Date: 04/06/2000
• Status: Expired due to Fees

• Current Assignee: ABB AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Hölleland, Mons, Svensen, Kirsti S., Sporild, Roald, Sipi, Marco, Lundmark, Maria, Sande, Eivind, Leijon, Mats, Berggren, Bertil, Rothman, Bengt, Midtgård, Ole-Morten
• Primary Examiner(s): Lam, Thanh
• Application Number:
  US10/239,883
• Publication Number:
  US 20030146731A1
• Time in Patent Office: 480 Days
• Field of Search: 310/68.C, 310/51, 310/54, 310/60.R, 310/61-65
• US Class Current: 310/51
• CPC Class Codes: H02J 3/1885 using rotating means, e.g. synchronous generators
• CPC Class Codes: H02K 11/25 Devices for sensing temperature, or actuated thereby
• CPC Class Codes: H02K 9/197 in which the rotor or stator space is fluid-tight, e.g. to provide for different cooling media for rotor and stator
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

For a method of operating of a synchronous compensator including a rotating electric machine including a rotor and a stator with at least one winding with a solid insulation enclosing the electric field, relevant parameters for temperature conditions in the rotor are determined, and during over-excited operation, to temporarily enlarge the field of operation of the synchronous compensator, cooling of the rotor is forced depending on a rotor temperature value determined from the parameters. The synchronous compensator measures parameters relevant for the temperature conditions of the rotor. A mechanism is also provided to force the cooling of the rotor depending on rotor temperature values determined from the parameters during over-excited operation of the electric machine.

Claims

1. Method of operation of a synchronous compensator including a rotating electric machine including a rotor and a stator with at least one winding with solid insulation enclosing an electric field, the method comprising:

determining, to temporarily enlarge a range of operation of the synchronous compensator, parameters relevant for temperature conditions in the rotor; and

forcing, at an over-excited operation, cooling of the rotor depending on a magnitude of a rotor temperature value determined from the parameters.

2. Method according to claim 1, wherein the machine is further configured to permit overload at an under-excited operation.

3. Method according to claim 2, further comprising:

determining parameters relevant for temperature conditions in the stator; and

reducing inductor current if a critical stator temperature is exceeded during the over-excited or under-excited operation.

4. Method according to claim 1, wherein the machine is configured for large short-circuit power.

5. Method according to claim 1, wherein an inductor current is reduced if the rotor temperature value exceeds a predetermined first temperature limit value, and the cooling of the rotor is forced if the rotor temperature value exceeds a predetermined second temperature limit value that is lower than the first temperature limit value.

6. Method according to claim 1, wherein the cooling is forced by lowering a temperature of a cooling medium.

7. Method according to claim 1, wherein the cooling is forced by increasing a flow of a cooling medium.

8. Method according to claim 1, wherein in the forcing, the rotor temperature value is determined from one or more of the parameters of inductor current, inductor voltage, temperature directly measured on the rotor, rotor cooling medium temperature, and cooling medium flow velocity.

9. Method according to claim 1, wherein the cooling is controlled at an actual overload so that a rotor temperature value will be equal to or less than a maximum allowable rotor temperature.

10. Synchronous compensator, comprising:

a rotating electric machine with at least one winding with solid insulation enclosing an electric field; and

measuring means for measuring parameters relevant for temperature conditions in the rotor; and

means for forcing cooling of the rotor depending on a value of a rotor temperature value determined from said parameters during an over-excited operation of the electric machine.

11. Synchronous compensator according to claim 10, further comprising:

a temperature estimator configured to determine a stator temperature value from one or more of parameters of stator current, stator voltage, sheet iron temperature directly measured on the stator, temperature of a stator cooling medium, and flow velocity of the stator cooling medium.

12. Synchronous compensator according to claim 10, wherein said means for forcing cooling forces the cooling by lowering a temperature of a cooling medium.

13. Synchronous compensator according to claim 10, wherein said means for forcing cooling forces the cooling by increasing a flow of a cooling medium.

14. Synchronous compensator according to claim 10, wherein said means for forcing cooling comprises switching means for switching a cooling circuit from a normal series arrangement in the rotor to a parallel arrangement.

15. Synchronous compensator according to claim 12, wherein the cooling medium is a liquid.

16. Synchronous compensator according to claim 10, further comprising:

a temperature estimator configured to determine a critical rotor temperature value from one or more of measured rotor temperature, temperature of a rotor cooling medium, and flow velocity of the rotor cooling medium.

17. Synchronous compensator according to claim 16, further comprising:

communication equipment configured for wireless transmission of measured values from a temperature gauge located on the rotor to the temperature estimator.

18. Synchronous compensator according to claim 17, wherein the communication equipment is configured for transmission of measured values from a temperature gauge located on the rotor by Bluetooth technology.

19. Synchronous compensator according to claim 10, further comprising:

a winding comprising a flexible cable with an electrically conducting core surrounded by an insulating system of two semiconductive layers with intermediate solid insulation.