DC circuit breaker

Patent metadata

Field	Value
Publication number	US-10418210-B2
Application number	US-201515540953-A
Country	US
Kind code	B2
Filing date	Dec 24, 2015
Priority date	Dec 29, 2014
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

Disclosed is a DC circuit breaker capable of interrupting fault currents flowing in both forward and backward directions. The DC circuit breaker includes: a first mechanical switch for interrupting a current in a DC transmission line; a first diode connected in parallel with the first mechanical switch; a second mechanical switch, connected in series with the first mechanical switch, for interrupting a current in the DC transmission line; a second diode connected in parallel with the second mechanical switch; an LC circuit connected in parallel with the first and second mechanical switches and including a capacitor and a reactor connected in series to induce LC resonance; a first unidirectional switching device connected in parallel with the LC circuit and switching a current to induce LC resonance; and a bidirectional switching device connected in series with the LC circuit and switching currents flowing in both forward and backward directions.

First claim

The invention claimed is:

1. A DC circuit breaker comprising:
a first mechanical switch installed on a DC transmission line and being opened to interrupt a current in the DC transmission line when a fault occurs at one side thereof on the DC transmission line;
a first diode connected in parallel with the first mechanical switch;
a second mechanical switch connected in series with the first mechanical switch and being opened to interrupt a current in the DC transmission line when a fault occurs at the remaining side thereof on the DC transmission line;
a second diode connected in parallel with the second mechanical switch;
an LC circuit connected in parallel with the first and second mechanical switches and including a capacitor and a reactor connected in series with each other to induce LC resonance;
a first unidirectional switching device, connected in parallel with the LC circuit, for switching a current flowing in one direction, to induce LC resonance; and
a bidirectional switching device, connected in series with the LC circuit, for switching currents flowing in both forward and backward directions.

2. The DC circuit breaker according to claim 1 , wherein the bidirectional switching device includes a pair of power semiconductor switches that are turn-on/turn-off controllable switches, are connected in parallel, and are arranged to be counter to each other, and wherein the first unidirectional switching device includes a power semiconductor switch that is a turn-on/turn-off controllable switch.

3. The DC circuit breaker according to claim 2 , wherein when a fault occurs at the one side of the DC circuit breaker on the DC transmission line, in a state in which the first mechanical switch is open and the bidirectional switching device is in an OFF state, the first unidirectional switching device is turned on such that the capacitor is charged to a voltage −Vc through LC resonance between the capacitor and the reactor of the LC circuit, and subsequently the first unidirectional switching device is turned off and the first power semiconductor switch of the bidirectional switching device is turned on such that a current is supplied through a closed circuit of the second mechanical switch and the first diode due to the voltage −Vc charged in the capacitor, thereby preventing a current from being supplied to the first mechanical switch.

4. The DC circuit breaker according to claim 3 , wherein when a fault occurs at the one side of the DC circuit breaker on the DC transmission line, opening the first mechanical switch and changing the capacitor to the voltage −Vc through the first unidirectional switching device that is turned on are simultaneously performed, or sequentially performed in this order or in a reverse order.

5. The DC circuit breaker according to claim 3 , wherein as a current is supplied to the first diode, a transient recovery voltage generated in the first mechanical switch is lowered by a reverse voltage that is applied between terminals of the first mechanical switch due to the current supply to the first diode.

6. The DC circuit breaker according to claim 2 , wherein when a fault occurs at the remaining side of the DC circuit breaker on the DC transmission line, the second mechanical switch is opened and the second power semiconductor switch of the bidirectional switching device is turned on such that a current is supplied through a closed circuit of the first mechanical switch and the second diode due to a voltage +Vc stored in the capacitor, thereby preventing a current from being supplied to the second mechanical switch.

7. The DC circuit breaker according to claim 6 , wherein when a fault occurs at the remaining side of the DC circuit breaker on the DC transmission line, opening the second mechanical switch and supplying the current through the closed circuit of the first mechanical switch and the second diode using the voltage +Vc stored in the capacitor are simultaneously performed or sequentially performed in this order or a reverse order.

8. The DC circuit breaker according to claim 6 , wherein as a current is supplied to the second diode, a transient recovery voltage generated in the second mechanical switch is lowered by a reverse voltage applied between terminals of the second mechanical switch.

9. The DC circuit breaker according to claim 6 , further comprising a second unidirectional switching device connected in parallel with the first unidirectional switching device and switching a current flowing in a reverse direction with respect to the current switched by the first unidirectional switching device to induce LC resonance in the LC circuit.

10. The DC circuit breaker according to claim 9 , wherein after a fault current is interrupted in the second mechanical switch, the second unidirectional switching device is turned on such that the capacitor is charged to a voltage −Vc through the LC resonance caused by the capacitor and the reactor.

11. The DC circuit breaker according to claim 1 , further comprising a resistor installed between a ground and a contact point between the LC circuit and the bidirectional switching device.

Assignees

• Hyosung Heavy Ind Corp

Inventors

• Kim Byung Choul
• Han Se Hee
• Hong Jung Ki
• Han Young Seong

Classifications

• H01H33/703

  having special gas flow directing elements, e.g. grooves, extensions · CPC title

• H02H3/021

  concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order (disconnection at zero value in general H03K17/18) · CPC title

• H01H33/596 Primary

  for interrupting DC · CPC title

• H02H3/087 Primary

  for DC applications · CPC title

• H01H33/143

  of different construction or type · CPC title