Distribution board bus arc light protection method suitable for air type circuit breaker occasion

Abstract

The invention relates to a distribution board bus arc light protection method suitable for an air-type circuit breaker occasion, and the method comprises the steps: when monitoring that the current value of at least one branch is increased sharply and a breaking action signal is sent, monitoring that a medium-voltage chamber generates arc light in a breaking realization time window, judging that an arcing fault occurs, and carrying out the arc light protection. A tripping signal is sent to a corresponding circuit breaker in a corresponding medium-voltage chamber; and when the time window of the breaking realization is exceeded, the arc light monitoring controller is locked, and even if an arc light signal occurs later, the arc light monitoring controller does not perform judgment operation on the arc light signal. The problem that conventional arc light protection is not suitable for medium-voltage direct-current occasions where air circuit breakers are applied is solved, the application range of arc light protection is widened, and the bus protection in a medium-voltage direct-current distribution board cabinet is achieved. Only a current sensor, an arc light sensor and a comprehensive controller which are deployed by conventional arc light protection are adopted, no additional sensor is arranged, the adaptability is improved only by adding judgment logic, and no additional implementation cost is brought.

Description

Technical Field

[0001] The invention relates to the technical field of power protection, and in particular to a distribution board busbar arc protection method suitable for air circuit breakers. Background Art

[0002] Among the various types of short-circuit faults in the medium-voltage AC power system of ships, busbar short-circuit faults can cause arcing in the distribution board. When a busbar short-circuit fault occurs and is not removed in time, the internal fault arcing will continue to burn the distribution board and release huge energy, damaging the components in the distribution board and posing a serious threat to the life and safety of the crew. Arc protection, as a sensitive and fast form of busbar protection, improves the speed of fault handling, can effectively solve the damage caused by arcing inside the distribution board, reduces equipment maintenance and casualties, and improves the safety and economic benefits of the system. It is generally used as the main protection for busbar protection. Usually, the arc and current signal dual judgment criteria are used. When an arc is detected in a certain medium-voltage room (busbar room, circuit breaker room, cable room), and at least one current value surges, it is judged as an internal arcing fault in the distribution board, and a trip signal is sent to the corresponding circuit breaker adjacent to the main busbar to remove the busbar fault.

[0003] Vacuum circuit breakers are often used in the distribution boards of ship power stations that use medium-voltage AC power. When the circuit breaker is disconnected, no arc will be generated in the cabinet, but when the fault arcs inside the distribution board, a violent arc will be generated. The judgment criteria are clear and there will be no confusion. In the medium-voltage DC distribution boards of ships that use medium-voltage DC power, air circuit breakers are generally used, which exposes a significant deficiency of conventional arc protection. That is, when air circuit breakers are used as the disconnecting means in the distribution board, violent arcs will also be generated when the air circuit breakers disconnect the current, which is difficult to distinguish from the arcs when the main busbar of the distribution board is short-circuited. At the same time, the current overcurrent condition is also met, so that the generators, busbars, jumpers and other loads connected to this section of the bus are non-selectively cut off, which eventually leads to the expansion of the fault area. This defect limits the applicability of arc protection, especially its application in the medium-voltage DC system of new ships. Summary of the invention

[0004] Aiming at the problem of how to distinguish the arc caused by air circuit breaker interruption from the arc caused by internal fault of distribution board, a busbar arc protection method for distribution board suitable for air circuit breaker occasions is proposed.

[0005] The technical solution of the present invention is: a distribution board busbar arc protection method suitable for air circuit breaker occasions. When a current value of at least one branch is monitored to surge and a disconnection action signal is issued, within the time window for disconnection, an arc is detected in the medium-voltage chamber, then it is judged as an arcing fault, and a tripping signal is issued to the corresponding circuit breaker in the corresponding medium-voltage chamber; when the time window for disconnection is exceeded, the arc monitoring controller is locked, and even if an arc signal appears thereafter, the arc monitoring controller does not make a judgment operation on it.

[0006] Furthermore, the time window for achieving the disconnection is determined by the stroke of the mechanical action mechanism of the air circuit breaker.

[0007] A protection system for realizing a distribution board busbar arc protection method suitable for air circuit breakers includes a current sensing unit, an arc sensing unit, and an arc monitoring controller.

[0008] The current sensing unit collects branch current parameters and outputs an action signal to the arc monitoring controller when the collected current exceeds a set threshold;

[0009] The arc sensing unit collects arc signals from the compartments, and when arc is detected in the compartments, outputs an action signal to the arc monitoring controller;

[0010] The arc monitoring controller collects the action signals of the current sensing unit and the arc sensing unit, performs comprehensive logic judgment, and when it is judged that the arc protection action is caused by the arc burning in the cabinet, sends a trip signal to the corresponding circuit breaker to cut off the fault.

[0011] The beneficial effects of the present invention are as follows: the present invention is applicable to the distribution board bus arc protection method in air circuit breaker occasions, which solves the problem that conventional arc protection cannot be applied to medium-voltage DC occasions using air circuit breakers, improves the application scope of arc protection, and solves the implementation difficulty of bus protection in medium-voltage DC distribution board cabinets; only current sensors, arc sensors and integrated controllers deployed by conventional arc protection are used, without additional sensors, and the adaptability is improved only by adding judgment logic, without incurring additional implementation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a structural diagram of the arc protection system proposed in the present invention. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0014] The arc protection system structure proposed by the present invention is shown in the attached figure. Figure 1 As shown. The system structure is mainly composed of current sensing unit, arc sensing unit and arc monitoring controller. The functions of each device are as follows:

[0015] (1) Current sensing unit: collects branch current parameters and outputs an action signal to the arc monitoring controller when the collected current exceeds the set threshold.

[0016] (2) Arc sensing unit: collects arc signals from the compartment. When an arc is detected in the compartment, it outputs an action signal to the arc monitoring controller.

[0017] (3) Arc monitoring controller: collects the action signals of the current sensing unit and the arc sensing unit, and performs comprehensive logical judgment. When it is determined that the arc protection is activated due to the arc burning in the cabinet, a trip signal is sent to the corresponding circuit breaker to eliminate the fault.

[0018] The protection implementation plan is as follows:

[0019] When the arc monitoring controller detects that the current value of at least one branch surges and sends out a disconnection action signal, it waits for a period of time (determined by the stroke of the mechanical action mechanism of the air circuit breaker, generally about 2-5ms). During this time window, if the arc monitoring controller detects that an arc is generated in a certain medium-voltage chamber (busbar chamber, circuit breaker chamber, cable chamber), it is judged as an arcing fault and a tripping signal is sent to the corresponding circuit breaker in the corresponding medium-voltage chamber. When this time window is exceeded, the arc monitoring controller is locked. Even if an arc signal appears thereafter, the arc monitoring controller still does not make any judgment. That is, the source of the arc is judged based on whether the fault current overcurrent and the arc signal appear synchronously as a criterion to determine the output result. When the arc is generated by an arc caused by an internal fault in the distribution board, the arc monitoring controller will act when the fault current and the arc signal appear synchronously; when the arc is generated due to the air circuit breaker disconnecting the short-circuit current, the arc signal lags behind the fault current and acts to lock.

[0020] The following three typical cases of arcing inside the distribution board, short-circuit current interruption by air circuit breakers, and out-of-zone short circuit outside the distribution board illustrate the specific implementation plans of the invention.

[0021] (1) Fault arcing occurs inside the distribution board

[0022] Generally, the fault arc occurs inside the distribution board due to busbar short circuit. At this time, the fault short-circuit current appears. At this time, at least one current value will be monitored to surge, meeting the current overcurrent criterion, and a 2-5ms time window will be opened. Due to the internal fault arc, the violent arc released by the busbar will instantly trigger the arc probe action signal, that is, the arc signal is received within the time window, and it is considered that the overcurrent signal and the arc signal appear simultaneously, then it is judged as an arc fault, and a trip signal is sent to the corresponding circuit breaker to remove the busbar fault.

[0023] (2) Air circuit breaker interrupts short-circuit current

[0024] At this time, other protection devices usually issue a tripping command to disconnect the air circuit breaker. At this time, a severe fault current must flow through the circuit breaker, satisfying the current overcurrent criterion and opening a 2-5ms time window. Since the air circuit breaker needs to mechanically drive the contact through the action mechanism after receiving the disconnection signal, there is a hysteresis time of at least 5ms, and no arc will appear during this time. After 5ms, the contacts are pulled apart to produce a severe arc. Even if an arc signal appears but the time window has been exceeded, the arc protection is effectively locked and will not malfunction.

[0025] (3) Out-of-area short circuit occurs outside the distribution board

[0026] When an out-of-zone short circuit occurs outside the distribution board, a fault overcurrent signal will appear, but since there will be no arc on the busbar, if the circuit breaker in the distribution board does not operate according to the system protection selective coordination logic, there will be no arc and the arc protection will not operate. If the circuit breaker in the distribution board needs to operate according to the system protection selective coordination logic, it will be merged into the second case.

[0027] The above three situations of arcing due to fault inside the distribution board, short-circuit current interrupted by air circuit breaker, and short circuit outside the distribution board cover all possible situations. It operates effectively when arcing due to internal fault occurs in the distribution board, and is effectively locked in other situations, which verifies the effectiveness of the proposed scheme.

[0028] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A distribution board busbar arc protection method suitable for air circuit breakers, characterized in that: When a current surge is detected in at least one branch and a disconnection action signal is issued, if an arc is detected in the medium voltage chamber within the time window for disconnection, it is judged as an arcing fault and a tripping signal is issued to the corresponding circuit breaker in the corresponding medium voltage chamber; when the time window for disconnection is exceeded, the arc monitoring controller is locked, and even if an arc signal appears thereafter, the arc monitoring controller will not make any judgment on it.

2. The arc protection method for distribution board busbars suitable for air circuit breakers according to claim 1 is characterized in that: The time window for disconnection is determined by the stroke of the mechanical action mechanism of the air circuit breaker.

3. A protection system for realizing a distribution board busbar arc protection method suitable for air circuit breakers, characterized in that: Including current sensing unit, arc sensing unit, arc monitoring controller, The current sensing unit collects branch current parameters and outputs an action signal to the arc monitoring controller when the collected current exceeds a set threshold; The arc sensing unit collects arc signals from the compartment, and when arc is detected in the compartment, outputs an action signal to the arc monitoring controller; The arc monitoring controller collects the action signals of the current sensing unit and the arc sensing unit, performs comprehensive logic judgment, and when it is judged that the arc protection action is caused by the arc burning in the cabinet, sends a trip signal to the corresponding circuit breaker to cut off the fault.

Images