Reactive power compensator

Patent metadata

Field	Value
Publication number	US-9335776-B2
Application number	US-201314036391-A
Country	US
Kind code	B2
Filing date	Sep 25, 2013
Priority date	Oct 5, 2012
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A reactive power compensator for a three-phase network having first, second and third phases includes an assembly of capacitors and electromechanical contactors electrically connected to the capacitors. Each contactor includes at least one upstream and one downstream power terminal. An electric current circulates between the upstream and downstream power terminals when the contactors are closed. A first contactor is connected to the first phase and a second contactor is connected to the third phase. The voltage between the upstream and downstream power terminals of at least one electromechanical contactor is measured so that the electromechanical contactors can be controlled according to a control algorithm. The control algorithm includes the closure of a contactor for a substantially zero voltage between the upstream and downstream power terminals thereof, and the opening a contactor for a substantially minimum power value of the capacitors to which the contactor is connected.

First claim

The invention claimed is:

1. A reactive power compensator for a three-phase network having a first phase, a second phase and a third phase, the compensator comprising:
an assembly of capacitors;
at least two electromechanical contactors electrically connected to the assembly of capacitors, each contactor comprising at least one upstream power terminal and at least one downstream power terminal, an electric current circulating between the upstream and downstream power terminals in the closed position of the contactor, a first electromechanical contactor being configured to connect to the first phase and a second electromechanical contactor being configured to connect to the third phase; and
circuitry configured to
measure the voltage between the upstream and downstream power terminals of at least one electromechanical contactor, and
control the electromechanical contactors according to a predetermined control algorithm,

wherein the control algorithm includes closure of one of the first or second electromechanical contactors for a substantially zero voltage between the upstream and downstream power terminals thereof, and opening of another of the first or second electromechanical contactors for a substantially minimum power value of the capacitor or the capacitors to which the other of the first or second electromechanical contactor is connected, and
wherein the circuitry is further configured to measure only the voltage between the upstream and downstream power terminals of the first electromechanical contactor, the closure of the first electromechanical contactor being determined on the basis of the voltage measured, closure of the second electromechanical contactor being determined as a function of the closure of the first electromechanical contactor with a predetermined time delay between the closure of the first electromechanical contactor and the closure of the second electromechanical contactor.

2. The reactive power compensator according to claim 1 , wherein the circuitry is further configured to measure the voltage between the upstream and downstream power terminals of the first electromechanical contactor, and of the second electromechanical contactor, the closure of the second electromechanical contactor being determined on the basis of the voltage measured between the upstream and downstream power terminals of at least one of the first and second electromechanical contactors.

3. The reactive power compensator according to claim 1 , wherein the three-phase voltage of the network is periodic, and the predetermined time delay is substantially equal to one quarter of the three-phase voltage period.

4. The reactive power compensator according to claim 1 , comprising exactly two electromechanical contactors.

5. The reactive power compensator according to claim 1 , wherein the assembly of capacitors comprises three capacitors arranged according to a triangular configuration, a first capacitor being connected between the first and second phases, a second capacitor being connected between the second and third phases, and a third capacitor being connected between the first and third phases.

6. The reactive power compensator according to claim 2 , wherein the assembly of capacitors comprises three capacitors arranged according to a triangular configuration, a first capacitor being connected between the first and second phases, a second capacitor being connected between the second and third phases, and a third capacitor being connected between the first and third phases.

7. The reactive power compensator according to claim 3 , wherein the assembly of capacitors comprises three capacitors arranged according to a triangular configuration, a first capacitor being connected between the first and second phases, a second capacitor being connected between the second and third phases, and a third capacitor being connected between the first and third phases.

8. The reactive power compensator according to claim 4 , wherein the assembly of capacitors comprises three capacitors arranged according to a triangular configuration, a first capacitor being connected between the first and second phases, a second capacitor being connected between the second and third phases, and a third capacitor being connected between the first and third phases.

9. The reactive power compensator according to claim 5 , wherein conditions for opening the first electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 12=0

where U 31 represents the voltage at the terminals of the third capacitor and U 12 represents the voltage at the terminals of the first capacitor.

10. The reactive power compensator according to claim 6 , wherein conditions for opening the first electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 12=0

where U 31 represents the voltage at the terminals of the third capacitor and U 12 represents the voltage at the terminals of the first capacitor.

11. The reactive power compensator according to claim 1 , wherein the conditions for opening the first electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 12=0

where U 31 represents the voltage at the terminals of the third capacitor and U 12 represents the voltage at the terminals of the first capacitor.

12. The reactive power compensator according to claim 7 , wherein conditions for opening the first electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 12=0

where U 31 represents the voltage at the terminals of the third capacitor and U 12 represents the voltage at the terminals of the first capacitor.

13. The reactive power compensator according to claim 5 , wherein conditions for opening the second electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 23=0

where U 31 represents the voltage at the terminals of the third capacitor and U 23 represents the voltage at the terminals of the second capacitor.

14. The reactive power compensator according to claim 9 , wherein conditions for opening the second electromechanical contactor to obtain the minimum power value stored in the capacitors correspond to the following equation:
U 31− U 23=0

where U 31 represents the voltage at the terminals of the third capacitor and U 23 represents the voltage at the terminals of the second capacitor.

15. The reactive power compensator according to claim 1 , further comprising three contactors, each being configured to electrically connect to a respective phase of the network.

16. The reactive power compensator according to claim 1 , wherein closure of each electromechanical contactor corresponds to a zero voltage between the upstream and downstream power thereof within a first tolerance, the first tolerance being equal to plus or minus 800 μs.

17. The reactive power compensator according to claim 1 , wherein opening of each electromechanical contactor corresponds, within a second tolerance, to the minimum value the power of the capacitor or the capacitors to which said contactor is connected, the second tolerance being equal to plus or minus 500 μs.

18. The reactive power compensator according to claim 1 , wherein the circuitry is further configured to send control signals to the first and second electromec

Assignees

• Schneider Electric Ind Sas

Inventors

• Follic Stephane
• Orban Remy
• Urankar Lionel

Classifications

• Y02E40/30

  Reactive power compensation · CPC title

• G05F1/70 Primary

  Regulating power factor; Regulating reactive current or power · CPC title

• H02J3/1821

  using shunt compensators · CPC title

• H01H9/56

  for ensuring operation of the switch at a predetermined point in the AC cycle · CPC title

• H02J3/18 Primary

  Arrangements for adjusting, eliminating or compensating reactive power in networks · CPC title