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EP-4736209-A1 - ARRANGEMENT, SYSTEM, AND METHOD FOR BYPASSING FAULTY SUBMODULES IN AN ELECTRIC CIRCUIT BREAKER

EP4736209A1EP 4736209 A1EP4736209 A1EP 4736209A1EP-4736209-A1

Abstract

An arrangement for interrupting current (1 ) comprises a first and a second terminal (11,12) being adapted to electrically connect two sections (100,200) of a power system, the arrangement comprising a circuit breaker module (10) adapted to interrupt current The circuit breaker module (10) is provided between the first and second terminals (11, 12), forming a first current path between the first and second terminals (11, 12). By providing a bypass device (50) connected in parallel with the first current path, thereby forming a second current path between the first and second terminals (11, 12), wherein the bypass device (50) comprises a switch, preferably a mechanical switch, a faulty circuit breaker module does not impede the operation of the arrangement.

Inventors

  • NORRGA, STAFFAN

Assignees

  • Scibreak AB

Dates

Publication Date
20260506
Application Date
20240627

Claims (13)

  1. 1 . An arrangement for interrupting current (1 ) comprising a first and a second terminal (11 ,12) being adapted to electrically connect two sections (100,200) of a power system, the arrangement comprising a circuit breaker module (10) adapted to interrupt current, wherein the circuit breaker module (10) is provided between the first and second terminals (11 , 12), forming a first current path between the first and second terminals (11 , 12), c h aracteri zed by a bypass device (50) connected in parallel with the first current path, thereby forming a second current path between the first and second terminals (11 , 12), wherein the bypass device (50) comprises a switch, preferably a mechanical switch.
  2. 2. The arrangement according to claim 1 , wherein the bypass device (50) comprises a first and a second contact (52, 53), wherein the first contact (52) is movable so that a stable short-circuit can be formed by joining the first and second contacts together.
  3. 3. An arrangement according to claim 2, 2. wherein the first and second contacts (52, 53) form part of a vacuum interrupter.
  4. 4. An arrangement according to claim 2 or 3, wherein the first contact (52) is displaceable into contact with the second contact (53) by means of an electromechanical actuator, preferably a solenoid or a Thomson coil.
  5. 5. An arrangement according to claim 2 or 3, wherein the first contact (52) displaceable into contact with the second contact (53) by means of a pyro-electric actuator.
  6. 6. An arrangement according to claim 4 and 5, comprising a thrusting actuator adapted to directly push the first contact (52) into contact with the second contact (53).
  7. 7. An arrangement according to any one of claims 2-6, comprising a bistable mechanism (57) adapted to uphold sufficient contact pressure in the bypass device (50) after the switch has been closed.
  8. 8. An arrangement according to any one of claims 2-5, comprising a pin puller 58, preferably a pyrotechnical pin puller, for operating the switch.
  9. 9. An arrangement according to claim 2 or 8, comprising a spring-loaded mechanism (59) with a spring adapted to move the first contact into contact with the second contact, whereby the spring maintains a required contact pressure between the first and second contacts in the closed position, and an actuator adapted to release the spring-loaded mechanism.
  10. 10. An arrangement according to any one of claims 1 -9. where the circuit breaker module (10) is provided with a mechanical circuit breaker, normally carrying current between the first and second terminals (11 , 12), and a resonant circuit adapted to be excited to achieve a zero-crossing of the current through said mechanical circuit breaker.
  11. 11. An arrangement according to claim 1 -10, comprising a voltage source converter adapted to excite the resonant circuit to achieve a zero-crossing of the current through the mechanical circuit breaker.
  12. 12. A system for interrupting current comprising at least two arrangements for interrupting current according to any of the preceding claims, wherein the at least two arrangements for interrupting current are connected in series.
  13. 13. A method of operating a system for interrupting current according to any claims 1-10, comprising the following steps: identifying that a circuit breaker module (10) is faulty, and subsequently, activating an associated bypass device (50). —

Description

ARRANGEMENT, SYSTEM, AND METHOD FOR BYPASSING FAULTY SUBMODULES IN AN ELECTRIC CIRCUIT BREAKER Technical field [0001] This invention relates to electric circuit breakers. In particular, it relates to circuit breakers employing resonant circuits to achieve an artificial zero-crossing in the current through a mechanical circuit breaker whereby a current interruption can be made absent any zero-crossings in the primary current to be interrupted. Background art [0002] It is known that a circuit breaker for interrupting current when there are no zero crossings (such as in a DC current, for instance) can be designed by using a resonant circuit to impose a resonant current in a mechanical circuit breaker, such as a vacuum interrupter, carrying the line current, see Fig. 1 and Fig. 2. Opening the mechanical circuit breaker by itself will generally not eliminate the current; instead an arc will form inside the mechanical circuit breaker by which the current continues to flow. However, if the resonant current exceeds the line current a zerocrossing occurs whereby the current though the mechanical switch is interrupted. The current is then commutated into an energy absorbing device such as a metal- oxide surge arrester. As this device starts conducting the current it will provide a counter voltage that drives the line current to zero, whereby the current extinction process is completed. [0003] One variety of such an active resonant circuit breaker uses a power- electronic voltage source converter to excite the resonant circuit, see Fig. 3 and with reference to patent publications EP3398198B1 and EP3161846B1. This variety offers several benefits. A high resonance frequency can be used, which implies smaller components in the resonant circuit. Furthermore, the resonant process can be precisely controlled by the voltage source converter. The typical procedure for interrupting current using such a circuit breaker is as follows. Initially, the line current I current flows through a mechanical circuit breaker 1. To start the interruption process, the circuit breaker is opened, preferably using a fast actuator. The current keeps flowing by way of an arc inside the breaker. Next, an alternating voltage llo is produced by the voltage source converter 4 at the resonance frequency of the resonant circuit 3. This leads to a resonant current Io flowing through the resonant circuit with increasing amplitude. Notably, the resonant current also flows through the mechanical breaker. When the amplitude eventually exceeds the magnitude of the line current I a zero crossing will occur in the current though the mechanical circuit breaker Isw. This causes the arc to be quenched whereby Isw will stop flowing. As there is no other path for the line current I to flow it will be forced into a surge arrestor 2. The surge arrestor will generally be chosen so as to provide a counter voltage that is significantly higher than the driving voltage in the grid when a current flows through it. Thereby, the line current is forced to zero and the current interruption process is completed. [0004] An alternative embodiment of the mentioned circuit breaker using a voltage source to excite the resonant circuit is seen in Fig. 4. In this case the placement of the surge arrester has been altered to be connected in series with the inductor of the resonant circuit. Figure 4 also indicates how several sets of voltage source converters and resonant circuits can be connected in parallel to achieve a higher resonant current. [0005] It is also known that a circuit breaker for high voltage can be designed by series-connecting several circuit breaker modules 10 of the described kinds, designed for lower voltage, see Fig. 5. This brings the important benefit that the current interruption is still possible even if one of the circuit breaker modules fail to interrupt the current properly, as long as the combined voltage provided by the other modules is sufficient to bring the line current to zero. [0006] The mentioned types of circuit breaker do not provide a contact separation when in the open state since an energy absorbing device 2 is connected in parallel with the mechanical breaker 1 . This implies that a low current may flow even when the breaker is in the open state. It is therefore common practice to connect a switch in the form of a residual current breaker 5 in series with the main circuit breaker. The residual current breaker is then used to eliminate the current flowing though the energy absorption device and provide a galvanic separation in the path of the main current. The residual current breaker generally only needs very limited current interruption capability. [0007] It is often beneficial to use the mentioned residual current breaker for closing the current circuit. By this method of closing the circuit, the circuit breaker modulelO is normally in the closed state, or in case it consists of several series connected breaker modules all of these are cl