Excitation inrush-current suppression system

Patent metadata

Field	Value
Publication number	US-9502189-B2
Application number	US-201314105846-A
Country	US
Kind code	B2
Filing date	Dec 13, 2013
Priority date	Dec 14, 2012
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

According to an embodiment, when a transformer that is connected to a first power supply through a first breaker as well as to a second power supply through a second breaker is detected to be disconnected from the power supplies, a specific phase of the three phases of the first breaker is closed to suppress an excitation inrush current, based on calculated residual magnetic fluxes and a voltage of the first power supply, and thereafter, the remaining two phases are closed. Based on the calculated residual magnetic fluxes and a voltage of the second power supply, a specific phase of the three phases of the second breaker is closed to suppress an excitation inrush current, and thereafter, the remaining two phases are closed.

First claim

What is claimed is:

1. An excitation-inrush-current suppression system that suppresses an excitation inrush current of a transformer connected through a first breaker to a first power supply and connected through a second breaker to a second power supply, the system comprising:
a transformer-voltage measurement unit configured to measure three-phase alternating-current voltages of the transformer;
a transformer power-off detection unit configured to detect that the transformer is disconnected from the power supplies;
a residual magnetic flux calculation unit configured to calculate residual magnetic fluxes of three phases of the transformer, based on the three-phase alternating-current voltages measured by the transformer-voltage measurement unit, when the transformer is detected to be disconnected from the power supplies by the transformer power-off detection unit;
a first power-supply-voltage measurement unit configured to measure three-phase alternating-current voltages of the first power supply;
a first closing unit configured to close a specific phase of the three phases of the first breaker at a first closing phase for suppressing an excitation inrush current, the specific phase being either a phase having a maximum absolute value or a minimum absolute value among the residual magnetic fluxes of the three phases, based on the residual magnetic fluxes of the three phases of the transformer calculated by the residual magnetic flux calculation unit and the three-phase alternating-current voltages of the first power supply measured by the first power-supply-voltage measurement unit;
a second closing unit configured to close two phases other than the specific phase of the first breaker, at a second closing phase for suppressing an excitation inrush current, after closing the specific phase of the first breaker by the first closing unit;
a second power-supply-voltage measurement unit configured to measure three-phase alternating-current voltages of the second power supply;
a third closing unit configured to close a specific phase of the three phases of the second breaker at a third closing phase for suppressing an excitation inrush current, the specific phase being either a phase having a maximum absolute value or a minimum absolute value among the residual magnetic fluxes of the three phases, based on the residual magnetic fluxes of the three phases of the transformer calculated by the residual magnetic flux calculation unit and the three-phase alternating-current voltages of the second power supply measured by the second power-supply-voltage measurement unit; and
a fourth closing unit configured to close two phases other than the specific phase of the second breaker, at a fourth closing phase for suppressing an excitation inrush current, after closing the specific phase of the second breaker by the third closing unit.

2. The excitation-inrush-current suppression system of claim 1 , further comprising:
a first excitation-inrush-current suppression apparatus; and
a second excitation-inrush-current suppression apparatus, wherein
the first excitation inrush-current suppression apparatus comprises
a first transformer-voltage measurement unit as the transformer-voltage measurement unit,
a first transformer power-off detection unit as the transformer power-off detection unit,
a first residual magnetic flux calculation unit as the residual magnetic flux calculation unit,
the first power-supply-voltage measurement unit,
the first closing unit, and
the second closing unit, and

the second excitation-inrush-current suppression apparatus comprises
a second transformer-voltage measurement unit as the transformer-voltage measurement unit,
a second transformer power-off detection unit as the transformer power-off detection unit,
a second residual magnetic flux calculation unit as the residual magnetic flux calculation unit,
the second power-supply-voltage measurement unit,
the third closing unit, and
the fourth closing unit.

3. The excitation-inrush-current suppression system of claim 1 , wherein
the transformer power-off detection unit determines that the transformer is disconnected from the power supplies, when a signal indicating an opening status is received from each of the first breaker and the second breaker.

4. An excitation-inrush-current suppression system that suppresses an excitation inrush current of a transformer connected through a first breaker to a first power supply and connected through a second breaker to a second power supply, the system comprising:
a first excitation-inrush-current suppression apparatus; and
a second excitation-inrush-current suppression apparatus, wherein
the first excitation inrush-current suppression apparatus comprises
a first transformer-voltage measurement unit configured to measure three-phase alternating-current voltages of the transformer,
a first transformer power-off detection unit configured to detect that the transformer is disconnected from the power supplies by the first breaker,
a first residual magnetic flux calculation unit configured to calculate residual magnetic fluxes of three phases of the transformer, based on the three-phase alternating-current voltages measured by the first transformer-voltage measurement unit, when the transformer is detected to be disconnected from the power supplies by the first transformer power-off detection unit,
a first residual magnetic flux transmission unit configured to transmit the residual magnetic fluxes of the three phases of the transformer calculated by the first residual magnetic flux calculation unit to the second excitation-inrush-current suppression apparatus,
a first residual magnetic flux receiving unit configured to receive the residual magnetic fluxes of the three phases of the transformer from the second excitation-inrush-current suppression apparatus,
a first power-supply-voltage measurement unit configured to measure three-phase alternating-current voltages of the first power supply,
a first closing unit configured to close a specific phase of the three phases of the first breaker at a first closing phase for suppressing an excitation inrush current, the specific phase being either a phase having a maximum absolute value or a minimum absolute value among the residual magnetic fluxes of the three phases, based on the three-phase alternating-current voltages of the first power supply measured by the first power-supply-voltage measurement unit and residual magnetic fluxes of the three phases of the transformer calculated by the first residual magnetic flux calculation unit or the residual magnetic fluxes of the three phases of the transformer received by the first residual magnetic flux receiving unit, and
a second closing unit configured to close two phases other than the specific phase of the first breaker, at a second closing phase for suppressing an excitation inrush current, after closing the specific phase of the first breaker by the first closing unit, and

the second excitation-inrush-current suppression apparatus comprises
a second transformer-voltage measurement unit configured to measure three-phase alternating-current voltages of the transformer,
a second transformer power-off detection unit configured to detect that the transformer is disconnected from the power supplies by the second breaker,
a second residual magnetic flux calculation unit configured to calculate residual magnetic fluxes of three phases of the transformer, based on the three-phase alternating-current voltages measured by the second transformer-voltage measurement unit, when the transformer is detected to be disconnected from the power supplies by the second transformer power-off detection unit,
a second residual magnetic flux transmission unit configured to transmit the residual magnetic fluxes of the three phases o

Assignees

• Toshiba Kk

Inventors

• Maruyama Shiro
• Saito Minoru
• Koshizuka Tadashi
• Mitani Tomohiko

Classifications

• H01H9/563 Primary

  for multipolar switches, e.g. different timing for different phases, selecting phase with first zero-crossing · CPC title

• H02H9/002 Primary

  limiting inrush current on switching on of inductive loads subjected to remanence, e.g. transformers · CPC title