KR-20260062909-A - CIRCUIT BREAKER USING REVERSE CURRENT INJECTION

Abstract

A circuit breaker according to one aspect of the present invention is characterized by comprising: a main branch including first and second switches sequentially arranged based on the direction of current flow on a current path to be interrupted, and one or more fuse modules connected in parallel with the first switch; a reverse current injection branch including a third switch and configured to inject reverse current into the main branch when the third switch is turned on; and a controller that interrupts the current flowing on the current path by forming a current zero on the current path through the control of the on/off operation of the first to third switches.

Inventors

• 이원교

Assignees

• 한국전력공사

Dates

Publication Date

20260507

Application Date

20260407

Claims (1)

1. A main branch comprising first and second switches sequentially arranged based on the direction of current flow on a current path to be blocked, and one or more fuse modules connected in parallel with the first switch; A reverse current injection branch including a third switch and configured to inject reverse current into the main branch when the third switch is turned on; and A controller that blocks the current flowing in the current path by forming a current zero on the current path through the on/off operation control of the first to third switches; Includes, The above controller controls the on/off of the second and third switches complementarily to form a current zero point on the current path, and In a normal state where normal current flows on the above current path, the first and second switches are configured to remain in an ON state, and the third switch is configured to remain in an OFF state. The above controller differentially controls the on/off operation of the first to third switches according to the result of a comparison between the magnitude of the current to be cut off flowing on the current path and a preset reference value to form a current zero on the current path, and If the magnitude of the above-mentioned blocking target current is less than or equal to the above-mentioned reference value, the controller, After turning off the second switch, turn on the third switch, and A circuit breaker using reverse current injection, characterized in that the main branch and the reverse current injection branch are connected in parallel.

Description

Circuit Breaker Using Reverse Current Injection The present invention relates to a circuit breaker, and more specifically to a DC circuit breaker. DC power grids are garnering attention due to the expansion of renewable energy sources and distributed power generation, as well as the increase in DC loads. For the safe and reliable operation of DC power grids, DC circuit breakers are essential for interrupting short-circuit faults and isolating them from the normal system. To this end, various types of DC circuit breakers have been proposed. Mechanical breakers offer low power loss during the on-state but have the disadvantage of slow interruption times, while solid-state breakers enable rapid interruption but suffer from high power loss during the on-state. Hybrid breakers are attracting attention as they combine the advantages of both mechanical and solid-state breakers; they can reduce on-state losses and improve interruption times compared to mechanical switches. In particular, research on solid-state circuit breakers or hybrid circuit breakers utilizing semiconductor devices is actively being conducted. However, utilizing semiconductor devices requires complex control, and there are disadvantages that they are not economical due to the high losses and cost of the devices. Meanwhile, power fuses are currently primarily used in power distribution systems. Power fuses normally allow the nominal current to flow, but they interrupt the current in the event of high-magnitude overcurrents or short-circuit currents on transmission lines. The types of power fuses commonly used include current limiting and expulsion types. Current limiting fuses are also called current-limiting fuses because, due to their characteristics, they can limit the current magnitude before it reaches its maximum value during the interruption process. Current-limiting fuses are filled with materials such as silicon and interrupt fault current by melting surrounding materials to absorb the heat of the arc generated inside the fuse, thereby increasing the arc's resistance. They have the advantages of being relatively small, having high breaking capacity, and fast interruption speeds; however, they have the disadvantages of being prone to overvoltage during the process and being difficult to interrupt small overcurrents due to the characteristic that "the surrounding material melts to absorb heat and increase resistance." Expulsion fuses, also known as non-current-limiting fuses, are fuses that extinguish the arc at the current zero point by releasing gas upon a fault. Although their interruption speed is relatively slower, this results in less concern regarding overvoltage, and they have an advantage over current-limiting fuses in that they are easier to interrupt small overcurrents. However, due to the nature of extinguishing the arc through gas release, they generate significant noise during the interruption process and have the disadvantages of being large in size and having a small breaking capacity. Figures 1 and 2 are exemplary diagrams showing existing research on DC circuit breakers. FIG. 3 is a circuit diagram showing the circuit configuration of a circuit breaker according to the present embodiment. FIGS. 4 to 10 are exemplary diagrams showing the operation of a circuit breaker according to the present embodiment. Hereinafter, an embodiment of a circuit breaker according to the present invention will be described with reference to the attached drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intention or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification. FIG. 3 is a circuit diagram showing the circuit configuration of a circuit breaker according to the present embodiment, and FIGS. 4 to 10 are exemplary diagrams showing the operation of a circuit breaker according to the present embodiment. Referring to FIG. 3, the circuit breaker of the present embodiment includes a main branch (100), a reverse current injection branch (200), an energy dissipation branch (300), and a controller (400) that controls each switch (S1 - S4) included in each branch (100, 200). The main branch (100) corresponds to a branch containing a current path (L) to be blocked, and is configured to include first and second switches (S1, S2) sequentially arranged (connected) based on the direction of DC current flow (e.g., the direction of the arrow in FIG. 3) on the current path, and one or more fuse modules (FM) connected in parallel with the first switch (S1). FIG. 3 shows an example in which three fuse modules (FM) are included in the main branch (100), and each fuse module (FM) consists of a fourth switch (S4) and a fuse (F)