High-voltage dc current breaker and high-voltage dc current breaking method

Patent metadata

Field	Value
Publication number	US-2016285250-A1
Application number	US-201415027744-A
Country	US
Kind code	A1
Filing date	Sep 5, 2014
Priority date	Oct 7, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

Provided is a DC current breaker having a high-speed breaking function appropriate to a voltage-type converter and a DC current breaking method. In addition, provided is a DC current breaker and a DC current breaking method capable of reducing cost of the breaker and securing economical competiveness by using a relatively simple configuration. The DC current breaker for breaking a DC current at the time of occurrence of an accident includes: a main conduction unit including three high-speed mechanical switches installed to be connected in series to a main conduction path for conducting a normal-operation-state current; a power semiconductor switch installed to be connected in parallel to one high-speed mechanical switch among the high-speed mechanical switches installed in the main conduction unit for current breaking of the main conduction unit; a capacitor installed on a circuit connected in parallel to the main conduction path; and a surge arrester installed to be connected in parallel to the capacitor connected in parallel to the main conduction path. The DC current breaking method uses the DC current breaker.

First claim

1 . A DC current breaker for breaking a DC current at the time of occurrence of an accident, comprising:
a main conduction unit including a commutate switch, a protection switch, and a close/open switch which are connected in series to each other in this order on a main conduction path where a current is flowed in a normal operation state, the protection switch protecting the commutate switch, and the close/open switch finally breaking a flow of a current of the main conduction unit; a power semiconductor switch connected in parallel to the commutate switch; a capacitor connected in parallel to the commutate switch and the protection switch; and a surge arrester connected in parallel to the capacitor.

2 . The DC current breaker according to claim 1 , wherein the commutate switch is a mechanical switch having a rated voltage which is lower than rated voltages of the protection switch and the close/open switch.

3 . The DC current breaker according to claim 1 , wherein a forward voltage of the power semiconductor switch is lower than an arc voltage generated when the commutate switch is opened in a conduction state, and the power semiconductor switch is turned on by the arc voltage generated in the commutate switch, so that a current flowing through the main conduction unit is commutated to the power semiconductor switch.

4 . The DC current breaker according to claim 1 , wherein the commutate switch is a monostable switch, the commutate switch receives a trip signal of the DC current breaker to start an opening operation, and after a time point when the current of the main conduction unit is completely commutated to the capacitor, the commutate switch automatically returns to a closed state.

5 . The DC current breaker according to claim 1 , wherein an opening response characteristic of the commutate switch is faster than opening response characteristics of the protection switch and the close/open switch, so that an arc voltage is more speedily increased than those of the protection switch and the close/open switch.

6 . The DC current breaker according to claim 1 , wherein the capacitor has electrostatic capacitance so that, when a transient voltage applied at the time point when a current of the main conduction path is broken by the power semiconductor switch is shared by the protection switch and the commutate switch, a magnitude of a transient voltage across the protection switch and the commutate switch does not exceed a limit value of a withstand voltage of the power semiconductor switch.

7 . The DC current breaker according to claim 1 , further comprising a discharge unit for discharging a voltage charged in the capacitor after a DC current breaking operation is finally finished by the close/open switch.

8 . The DC current breaker according to claim 7 , wherein the discharge unit is configured to include a discharge switch and a discharge resistor which are connected in series to each other on a discharge path connected in parallel to the capacitor.

9 . The DC current breaker according to claim 1 , wherein the power semiconductor switch is formed with a single one-directional conduction switch or is formed by connecting two one-directional conduction switches reversely in series to each other and connecting free wheeling diodes in parallel to the respective one-directional conduction switches.

10 . A DC current breaking method for breaking a DC current at the time of occurrence of an accident by using a DC current breaker,
wherein the DC current breaker includes: a main conduction unit including commutate switch, a protection switch, and a close/open switch which are connected in series to each other in this order on a main conduction path where a current is flowed in a normal operation state, the protection switch protecting the commutate switch, and the close/open switch finally breaking a flow of a current of the main conduction unit; a power semiconductor switch connected in parallel to the commutate switch; a capacitor connected in parallel to the commutate switch and the protection switch; and a surge arrester connected in parallel to the capacitor, and wherein the DC current breaking method comprises: starting opening operations of the commutate switch, the protection switch 12 , and the close/open switch by applying a trip signal to the switches in the state that a current flow through the switches at the time of occurrence of the accident; if arc is generated between contacts of the commutate switch and, thus, the current flowing through the commutate switch is commutated to the power semiconductor switch, turning off the power semiconductor switch so that the current flowing through the main conduction path is commutated to the capacitor to charge the capacitor; and if a charge voltage of the capacitor is increased up to a discharge start voltage of the surge arrester, allowing the surge arrester to start discharging, so that the current flows through the surge arrester, and thus, energy on a line is absorbed by the surge arrester, so that the current is completely broken.

11 . The DC current breaking method according to claim 10 , wherein a time point when the power semiconductor switch is turned off according to a control signal of a control unit and, thus, a current flowing through the power semiconductor switch is broken is set to a time point when a distance between electrodes of the protection switch where arc is generated becomes a distance between the electrodes where insulation with respect to a transient voltage generated afterwards can be recovered.

12 . The DC current breaking method according to claim 10 , further comprising operating a discharge unit for discharging the voltage charged in the capacitor after the close/open switch is completely opened.

13 . The DC current breaking method according to claim 12 , wherein the discharge unit is configured to include a discharge switch and a discharge resistor which are connected in series to each other on a discharge path connected in parallel to the capacitor, and the discharge switch is closed and, after that, opened so that the voltage charged in the capacitor is discharged through the discharge path.

14 . The DC current breaking method according to claim 12 , further comprising closing the DC current breaker by closing the protection switch and, after that, closing the close/open switch.

Assignees

• Keri Korea Electrotechnology Res Inst

Inventors

• Lee Woo Young
• Park Sang Hun
• Song Ki Dong
• Jang Hyun Jae
• Chong Jin Kyo

Classifications

• H02H3/087 Primary

  for DC applications · CPC title

• H01H9/547

  Combinations of mechanical switches and static switches, the latter being controlled by the former · CPC title

• H01H9/542

  Contacts shunted by static switch means · CPC title

• H01H9/54 Primary

  Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere · CPC title

• H01H2009/546

  the static switching means being triggered by the voltage over the mechanical switch contacts · CPC title