Series compensation of electric alternating current machines

• US 6,465,979 B1
• Filed: 10/04/1999
• Issued: 10/15/2002
• Est. Priority Date: 02/03/1997
• Status: Expired due to Fees

• Current Assignee: Asea Brown Boveri AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Templin, Peter, Leijon, Mats, Gertmar, Lars, Nygren, Jan-Anders
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US09/355,852
• Time in Patent Office: 1,107 Days
• Field of Search: 318/438, 318/565, 318/568.22, 318/621, 318/632, 318/722, 318/729, 318/801, 318/140, 318/148, 174/115, 174/116, 174/DIG-13-, 361/42, 361/47, 361/48, 361/90, 361/91.1, 307/149, 307/151, 307/153
• US Class Current: 318/438
• CPC Class Codes: H02J 3/1807 using series compensators
• CPC Class Codes: H02K 2203/15 Machines characterised by cable windings, e.g. high-voltage cables, ribbon cables
• CPC Class Codes: Y02E 40/30 Reactive power compensation
• CPC Class Codes: Y10S 174/15 in a power generation system, e.g. prime-mover dynamo, generator system

Abstract

A method and device for providing series compensation for rotating electric alternating current machines connected either directly, or via a static current converter, to a three-phase distribution or transmission network. The stator of the electric machine is Y-connected. A capacitive circuit for the fundamental frequency of the voltage is connected to each phase between the low voltage side of the winding and a ground of the transmission network.

Claims

1. A method for providing series compensation of a rotating electric alternating current machine connected to a three-phase network for at least one of distribution and transmission, the three-phase network having a fundamental frequency, the rotating electric alternating current machine being one of directly connected to the three-phase network and connected via a static current converter, a stator winding of the rotating electric alternating current machine having three phases Y-connected, comprising the steps of:

connecting a down side of a first phase of the three phases of the stator winding to a first side of a first capacitive circuit;

connecting a second side of the first capacitive circuit to a ground of the three-phase network completing a first series capacitive circuit;

connecting a down side of a second phase of the three phases of the stator winding to a first side of a second capacitive circuit;

connecting a second side of the second capacitive circuit to the ground of the three-phase network completing a second series capacitive circuit;

connecting a down side of a third phase of the three phases of the stator winding to a first side of a third capacitive circuit;

connecting a second side of the third capacitive circuit to the ground of the three-phase network completing a third series capacitive circuit; and

lowering a reactance of a system including the rotating electric alternating current machine by compensating the three phases of the stator winding through respective series capacitive circuits.

2. A device for providing series compensation of a rotating electric alternating current machine connected to a three-phase network for at least one of distribution and transmission, the three-phase network having a fundamental frequency, the rotating electric alternating current machine being one of directly connected to the three-phase network and connected via a static current converter, a stator winding of the rotating electric alternating current machine having three phases Y-connected, comprising:

a first capacitive circuit having a first side and a second side, the first side connected to a down side of a first phase of the three phases of the stator winding and the second side connected to a ground of the three-phase network so as to create a first series capacitive circuit;

a second capacitive circuit having a first side and a second side, the first side connected to a down side of a second phase of the three phases of the stator winding and the second side connected to the ground of the three-phase network so as to create a second series capacitive circuit; and

a third capacitive circuit having a first side and a second side, the first side connected to a down side of a third phase of the three phases of the stator winding and the second side connected to the ground of the three-phase network so as to create a third series capacitive circuit, wherein

the first series capacitive circuit, the second series capacitive circuit, and the third series capacitive circuit are configured to lower a reactance of a system including the rotating electric alternating current machine by compensating the three phases of the stator winding through respective series capacitive circuits.

3. The device of claim 2, wherein:

the first series capacitive circuit includes a first capacitor;

the second series capacitive circuit includes a second capacitor; and

the third series capacitive circuit includes a third capacitor.

4. The device of claim 3, further comprising:

means for protecting from over-voltage connected in parallel with the first capacitor;

means for protecting from over-voltage connected in parallel with the second capacitor; and

means for protecting from over-voltage connected in parallel with the third capacitor.

5. The device of claim 2, further comprising:

a bandstop filter connected in series between a Y-point and the ground of the three-phase network, the Y-point including the second side of the first capacitive circuit, the second side of the second capacitive circuit and the second side of the third capacitive circuit.

6. The device of claim 5, further comprising a low-ohmic resistor connected in series between the bandstop filter and the ground of the three-phase network.

7. A rotating electric alternating current machine, comprising:

a stator having slots;

a stator winding drawn through the slots of the stator, the stator winding being a high-voltage cable; and

a series compensation device having

a first capacitive circuit having a first side and a second side, the first side connected to a down side of a first phase of three phases of the stator winding and the second side connected to a ground of a three-phase network so as to create a first series capacitive circuit;

a second capacitive circuit having a first side and a second side, the first side connected to a down side of a second phase of the three phases of the stator winding and the second side connected to the ground of the three-phase network so as to create a second series capacitive circuit; and

a third capacitive circuit having a first side and a second side, the first side connected to a down side of a third phase of the three phases of the stator winding and the second side connected to the ground of the three-phase network so as to create a third series capacitive circuit, wherein

the three-phase network is for at least one of distribution and transmission, the three-phase network has a fundamental frequency, and

the first series capacitive circuit, the second series capacitive circuit, and the third series capacitive circuit are configured to lower a reactance of a system including the rotating electric alternating current machine by compensating the three phases of the stator winding through respective series capacitive circuits.

8. The rotating electric alternating current machine of claim 7, wherein the stator winding comprise s a high-voltage cable having,

a core having a plurality of conductive strands,

an inner semiconducting layer surrounding the core,

an insulating layer surrounding the inner semiconducting layer, and

an outer semiconducting layer surrounding the insulating layer.

9. The rotating electric alternating current machine of claim 8, wherein the high-voltage cable has a diameter in an inclusive range of 20 through 200 mm, and a conducting area in an inclusive range of 80 through 3000 mm².

10. The rotating electric alternating current machine of claim 8, wherein:

the high-voltage cable is flexible,

the inner semiconducting layer is in contact with the core,

the insulating layer is in contact with the inner semiconducting layer, and

the outer semiconducting layer is in contact with the insulating layer.

11. The rotating electric alternating current machine of claim 8, wherein:

the inner semiconducting layer, the insulating layer, and the outer semiconducting layer are configured to have an elasticity and coefficients of thermal expansion such that a change in a volume of the layers caused by a change in temperature is absorbed such that the inner semiconducting layer maintains contact with the core, the insulating layer maintains contact with the inner semiconducting layer, and the outer semiconducting layer maintains contact with the insulating layer.

12. The rotating electric alternating current machine of claim 8, wherein:

the inner semiconducting layer, the insulating layer, and the outer semiconducting layer are configured to have a modulus of elasticity less than 500 MPa.

13. The rotating electric alternating current machine of claim 8, wherein:

the inner semiconducting layer, the insulating layer, and the outer semiconducting layer are configured to have substantially the same coefficient of thermal expansion.

14. The rotating electric alternating current machine of claim 8, wherein:

an adhesion between the layers being at least as strong as a strength of a weakest material in the layers.

15. The rotating electric alternating current machine of claim 8, wherein:

the inner semiconducting layer comprises an equipotential surface, and

the outer semiconductor layer comprises an equipotential surface.

16. The rotating electric alternating current machine of claim 8, wherein:

the inner semiconducting layer, the insulating layer, and the outer semiconducting layer are configured to have a modulus of elasticity less than 200 MPa.