CN116470467A - Control method and control system of circuit breaker - Google Patents

Control method and control system of circuit breaker Download PDF

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Publication number
CN116470467A
CN116470467A CN202310510885.9A CN202310510885A CN116470467A CN 116470467 A CN116470467 A CN 116470467A CN 202310510885 A CN202310510885 A CN 202310510885A CN 116470467 A CN116470467 A CN 116470467A
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CN
China
Prior art keywords
current
circuit breaker
time
circuit
sampling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310510885.9A
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Chinese (zh)
Inventor
徐张英
渠晓敏
刘晓芝
洪景鹏
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhejiang Huakai Electric Co ltd
Original Assignee
Zhejiang Huakai Electric Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhejiang Huakai Electric Co ltd filed Critical Zhejiang Huakai Electric Co ltd
Priority to CN202310510885.9A priority Critical patent/CN116470467A/en
Publication of CN116470467A publication Critical patent/CN116470467A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/093—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current with timing means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/54—Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
    • H01H9/56—Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere for ensuring operation of the switch at a predetermined point in the ac cycle
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/027—Details with automatic disconnection after a predetermined time
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Keying Circuit Devices (AREA)

Abstract

The application provides a control method and a control system of a circuit breaker, wherein the control method of the circuit breaker comprises the following steps: calculating a current effective value of the current carrying circuit, and judging whether the current effective value reaches a current threshold value or not; if the current effective value reaches the current threshold value, determining the execution time; when the execution time is reached, sending a trigger instruction to the circuit breaker so that the circuit breaker is opened at a target time in response to the trigger instruction; the difference value between the target time and the current period is within a first preset range; the current period is the time corresponding to the current zero crossing point in the current carrying circuit; the circuit breaker is connected in a current carrying circuit which is disconnected when the circuit breaker is opened. Therefore, in the application, when the current in the current-carrying circuit is overloaded, the circuit breaker is disconnected at the current zero crossing point or near the current zero crossing point in a hardware sampling and software control mode, the generation intensity of the electric arc is reduced in the mode, the abrasion of the electric arc to the fixed contact and the fixed contact is effectively reduced, and the service life of the circuit breaker is prolonged.

Description

Control method and control system of circuit breaker
Technical Field
The application relates to the technical field of power grids, in particular to a control method and a control system of a circuit breaker.
Background
At present, a circuit breaker is usually arranged in a current-carrying circuit to realize that the circuit connection is disconnected when the current in the current-carrying circuit is overlarge, so that the current-carrying circuit is protected, and safety accidents are avoided. Specifically, the circuit breaker comprises a fixed contact and a moving contact, and when the fixed contact is disconnected with the moving contact, the circuit breaker can realize the outage of the whole current-carrying circuit, so as to protect the current-carrying circuit. However, when the fixed contact and the movable contact are disconnected, if the current in the current-carrying circuit is too large, an arc may occur between the fixed contact and the movable contact. The existence of the electric arc makes the circuit breaker unable to complete normal cutting-off work, the current-carrying circuit is unable to be completely cut off, still in the on state, there is a potential safety hazard. Meanwhile, the electric arc also damages the fixed contact and the moving contact, so that the fixed contact and the moving contact are worn, and the service life of the circuit breaker is influenced.
For this reason, in the prior art, an arc extinguishing device is usually provided in a circuit breaker, and the generated arc is introduced into an arc extinguishing chamber of the arc extinguishing device by means of a structural member, and is extinguished by the arc extinguishing chamber.
However, when the arc is extinguished in the manner, the arc extinguishing device is ablated each time, and after the arc extinguishing device is ablated, the arc extinguishing device loses the arc extinguishing capability; when the arc extinguishing device loses the arc extinguishing capability, the current carrying circuit cannot be completely cut off, and potential safety hazards exist in the circuit; meanwhile, the electric arc still damages the fixed contact and the moving contact, so that the fixed contact and the moving contact are worn, and the service life of the circuit breaker is influenced.
Disclosure of Invention
The embodiment of the application aims to provide a control method and a control system for a circuit breaker, which improve the service life of the circuit breaker.
In a first aspect, the present application provides a control method of a circuit breaker, the control method of the circuit breaker includes:
calculating a current effective value of the current carrying circuit, and judging whether the current effective value reaches a current threshold value or not;
if the current effective value reaches the current threshold value, determining the execution time;
when the execution time is reached, sending a trigger instruction to the circuit breaker so that the circuit breaker is opened at a target time in response to the trigger instruction; the difference value between the target time and the current period is within a first preset range; the current period is the time corresponding to the current zero crossing point in the current carrying circuit; the circuit breaker is connected in a current carrying circuit which is disconnected when the circuit breaker is opened.
In one embodiment, before calculating the current effective value of the current carrying circuit, the control method of the circuit breaker further comprises:
receiving a sampling signal of a current-carrying circuit sent by a current sampling circuit, and generating a current waveform according to the sampling signal; the current sampling circuit is connected with the current carrying circuit;
calculating a current effective value of the current carrying circuit, comprising:
calculating a current effective value according to the current waveform;
determining an execution time, comprising:
the execution time is determined from the current waveform.
In one embodiment, determining the execution time from the current waveform includes:
extracting a current period from the current waveform;
determining execution time according to the current period, the pre-stored delay time and the current time;
the delay time is the time difference from sending a trigger instruction to the circuit breaker to be disconnected, and the current time is the time when the current effective value reaches the current threshold value.
In one embodiment, determining the execution time according to the current period, the pre-stored delay time and the current time includes:
screening out characteristic time from the current period;
determining execution time according to the difference value of the first time difference and the delay time; the time difference between the characteristic time and the current time is the smallest, and the first time difference is the time difference between the characteristic time and the current time.
In one embodiment, after determining the execution time, the control method of the circuit breaker further includes:
judging whether the execution time meets a preset condition or not;
if the execution time does not meet the preset condition, determining the change period of the current in the current-carrying circuit according to the current waveform;
the execution time is redetermined based on the period of variation.
In one embodiment, before determining the execution time according to the current period, the pre-stored delay time and the current time, the control method of the circuit breaker further includes:
and receiving delay time.
In a second aspect, the present application provides a control system for a circuit breaker, the control system for a circuit breaker comprising:
a circuit breaker, a current carrying circuit and a control device; wherein the circuit breaker is connected in a current carrying circuit; the control device is positioned in the circuit breaker and is connected with the current-carrying circuit; the control device is used for calculating the current effective value of the current carrying circuit and executing the control method of the circuit breaker according to the calculation result of the current effective value.
In one embodiment, the control system of the circuit breaker further comprises a current sampling circuit; the current sampling circuit is positioned in the circuit breaker, and the control device is connected with the current carrying circuit through the current sampling circuit; the current sampling circuit is used for sending a sampling signal of the current carrying circuit to the control device, and the control device is used for generating a current waveform according to the sampling signal and calculating a current effective value according to the current waveform.
In one embodiment, the current sampling circuit includes an induction unit, a rectification unit, a sampling unit and an amplifying unit; the induction unit is connected with the current-carrying circuit and is used for inducing a current signal in the current-carrying circuit; the rectifying unit is connected with the induction unit and is used for rectifying the current signal transmitted by the induction unit; the sampling unit is connected with the rectifying unit and is used for sampling the current signal transmitted by the rectifying unit to generate a sampling signal; the amplifying unit is connected with the sampling unit and the control device and is used for amplifying the sampling signal transmitted by the sampling unit and transmitting the amplified sampling signal to the control device.
In one embodiment, the control device includes a judging module, a determining module and a transmitting module; the judging module is used for calculating the current effective value of the current carrying circuit and judging whether the current effective value reaches a current threshold value or not; the determining module is used for determining the execution time if the current effective value reaches the current threshold value; the sending module is used for sending a trigger instruction to the circuit breaker when the execution time is reached, so that the circuit breaker is opened at the target time in response to the trigger instruction.
The application provides a control method of a circuit breaker, which comprises the steps of firstly calculating a current effective value of a current carrying circuit, and judging whether the current effective value reaches a current threshold value after calculation is successful. And if the current effective value is detected to reach the current threshold value, determining the execution time. Further, when the execution time is reached, a trigger instruction is sent to the circuit breaker, so that the circuit breaker can be opened at a current zero crossing point after receiving the trigger instruction, or the circuit breaker can be opened near the current zero crossing point after receiving the trigger instruction.
Therefore, in the current-carrying circuit, when the current is overloaded, the circuit breaker is disconnected at the current zero crossing point or near the current zero crossing point in a hardware sampling and software control mode, the generation intensity of the electric arc is reduced in the mode, normal cutting-off work of the circuit breaker is ensured, and the use safety of the current-carrying circuit is ensured. Meanwhile, the abrasion of the electric arc to the fixed contact and the fixed contact can be effectively reduced by reducing the generation intensity of the electric arc, and the service life of the circuit breaker is greatly prolonged.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings that are required to be used in the embodiments of the present application.
Fig. 1 is a schematic structural diagram of a control system of a circuit breaker according to a first embodiment of the present application;
fig. 2 is a schematic structural diagram of a control system of a circuit breaker according to a second embodiment of the present application;
FIG. 3 is a schematic diagram illustrating connection between a control device and a current sampling circuit according to an embodiment of the present disclosure;
fig. 4 is a flow chart of a control method of a circuit breaker according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of a current waveform according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a control device according to a first embodiment of the present application;
fig. 7 is a schematic structural diagram of a control device according to a second embodiment of the present application.
Reference numerals;
1-a control system of a circuit breaker; a 10-current carrying circuit; a 20-circuit breaker; 210-control means; 211-a judging module; 212-a determination module; 213-a transmitting module; 214-a receiving module; 220-a current sampling circuit; a 221-sensing unit; 222-a rectifying unit; 223-sampling unit; 224-amplifying unit.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
Like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
Fig. 1 is a schematic structural diagram of a control system 1 of a circuit breaker according to an embodiment of the disclosure. As shown in fig. 1, the control system 1 of the circuit breaker in the present embodiment includes a circuit breaker 20 and a current-carrying circuit 10. The current-carrying circuit 10 is applied to a power grid, a plurality of loads are connected to the current-carrying circuit 10, and the current-carrying circuit 10 is used for providing electric energy for the loads so that the loads can normally operate. The load can be household electric equipment such as a refrigerator, a television, an LED lamp and the like; alternatively, the load may be an industrial consumer or the like. The circuit breaker 20 is connected in the current-carrying circuit 10, and is part of the current-carrying circuit 10; when the current in the current-carrying circuit 10 is too large, the current-carrying circuit 10 is easy to have potential safety hazards, and fire is easy to occur when serious; the circuit breaker 20 is used to protect the current carrying circuit 10, and when the current in the current carrying circuit 10 is excessive, the circuit breaker 20 opens to disconnect the current carrying circuit 10. In addition, the control system 1 of the circuit breaker in the present embodiment further includes a control device 210, the control device 210 is located inside the circuit breaker 20, and the control device 210 is connected with the current carrying current; the control device 210 is configured to calculate a current effective value of the current-carrying circuit 10, and when the control device 210 detects that the current effective value of the current-carrying circuit 10 is greater than a set threshold value, the control device 210 may control the circuit breaker 20 to open, thereby protecting the current-carrying circuit 10. Specifically, when it is detected that the current effective value of the current-carrying circuit 10 is greater than the set threshold value, the control device 210 can control the circuit breaker 20 to open by executing the control method of the circuit breaker 20 in the embodiment described below.
Fig. 2 is a schematic structural diagram of a control system 1 of a circuit breaker according to a second embodiment of the present disclosure. As shown in fig. 2, in the present embodiment, the control system 1 of the circuit breaker further includes a current sampling circuit 220; the current sampling circuit 220 is located inside the circuit breaker 20, and the control device 210 is connected with the current carrying circuit 10 through the current sampling circuit 220; the current sampling circuit 220 is configured to send a sampling signal of the current-carrying circuit 10 to the control device 210, and the control device 210 is configured to generate a current waveform according to the sampling signal and calculate a current effective value according to the current waveform. Further, the control device 210 may determine whether the current effective value is greater than a set threshold according to the calculation result of the current effective value; when it is determined that the current effective value is greater than the set threshold value, the control device 210 may control the circuit breaker 20 to be opened by executing the control method of the circuit breaker 20 in the embodiment described below.
Fig. 3 is a schematic diagram illustrating connection between the control device 210 and the current sampling circuit 220 according to an embodiment of the disclosure. As shown in fig. 3, the control device 210 has two connection terminals, namely a first connection terminal TF and a second connection terminal TQ, the first connection terminal TF is connected to the current sampling circuit 220, and the second connection terminal TQ is connected to the driving device in the circuit breaker 20. The current sampling circuit 220 includes a sensing unit 221, a rectifying unit 222, a sampling unit 223, and an amplifying unit 224.
The sensing unit 221 is connected to the current-carrying circuit 10, and the sensing unit 221 is used for sensing a current signal in the current-carrying circuit 10. Specifically, as shown in fig. 3, the sensing unit 221 may include a current transformer ZCT1, and an input terminal of the current transformer ZCT1 is connected in the current-carrying circuit 10. The rectifying unit 222 is connected to the sensing unit 221, and the rectifying unit 222 is used for rectifying the current signal transmitted by the sensing unit 221. Specifically, as shown in fig. 3, the rectifying unit 222 may include a rectifying bridge BR1, where two input ends of the rectifying bridge BR1 are respectively connected to output ends of the current transformer ZCT 1. The sampling unit 223 is connected to the rectifying unit 222, and the sampling unit 223 is configured to sample the current signal transmitted by the rectifying unit 222 to generate a sampling signal. Specifically, as shown in fig. 3, the sampling unit 223 includes a sampling resistor R1, one end of the sampling resistor R1 is connected to the output end of the rectifying unit 222, and the other end of the sampling resistor R1 is grounded. The resistance of the sampling resistor R1 may be 1 to 2R. The amplifying unit 224 is connected to the sampling unit 223 and the control device 210, and the amplifying unit 224 is configured to amplify the sampling signal transmitted by the sampling unit 223, and send the amplified sampling signal to the control device 210, so that the control device 210 generates a current waveform according to the sampling signal, and calculates a current effective value according to the current waveform. Specifically, as shown in fig. 3, the amplifying unit 224 may be an inverting amplifier, and the amplifying unit 224 includes a resistor R3, a resistor R2, a resistor R4, an operational amplifier, a capacitor C1, and a capacitor C3. One end of a resistor R3 is connected with the sampling unit 223, and the other end of the resistor R3 is connected with the operational amplifier, a capacitor C1 and a resistor R2; one end of the resistor R2 is connected with the resistor R3, and the other end of the resistor R2 is connected with the resistor R4; one end of a capacitor C1 is connected with a resistor R3, and the other end of the capacitor C1 is connected with a resistor R4; one end of the capacitor C3 is connected with the operational amplifier, and the other end of the capacitor C3 is grounded; one end of the resistor R4 is connected to the resistor R2, the capacitor C1, and the operational amplifier, respectively, and the other end of the resistor R4 is connected to the control device 210. The values of the resistors R3 and R2 reflect the amplification factor of the reverse proportional amplifier, and the resistance of the resistor R3 may be 10 to 20K and the resistance of the resistor R2 may be 20 to 30K, respectively. The capacitors C1 and C3 are used for filtering the sampled signal transmitted by the sampling unit 223, so as to avoid the noise signal in the sampled signal from generating interference. The resistor R4 is a connection resistor.
The operation principle of the current sampling circuit 220 is explained in detail below;
first, the sensing unit 221 senses a current signal SA according to an original current signal in the current-carrying circuit 10, wherein the current signal SA is equal to the original current signal in the current-carrying circuit 10. The sensing unit 221 then transmits the current signal SA to the rectifying unit 222, and the rectifying unit 222 rectifies the current signal SA. The rectifying unit 222 transmits the current signal to the sampling unit 223, the sampling unit 223 samples the current signal SA, and the sampled current signal SA is converted into a voltage signal BR-; the voltage signal BR-is the sampled signal generated after sampling, and the phase of the voltage signal BR-is 180 degrees different from the phase of the current signal SA. After the sampling IS successful, the sampling unit 223 transmits the voltage signal BR to the amplifying unit 224, the amplifying unit 224 reversely amplifies the voltage signal BR to obtain an amplified current signal IS with equal proportion, and then the amplifying unit 224 transmits the current signal IS to the control device 210; wherein the phase of the current signal IS 180 deg. out of phase with the phase of the voltage signal BR-. It follows that the phase of the current signal IS 180 ° out of phase with the voltage signal BR-which in turn IS 180 ° out of phase with the current signal SA, and that the phase of the current signal IS 0 ° or 360 ° out of phase with the current signal SA, i.e. the phase of the current signal IS the same as the phase of the current signal SA. Since the phase of the current signal SA IS the same as the phase of the original current signal in the current-carrying circuit 10, the phase of the summary current signal IS the same as the phase of the current signal in the current-carrying circuit 10. As can be seen from the above description, the phase of the sampled current signal sent by the current sampling circuit 220 to the control device 210 is the same as the phase of the original current signal in the current carrying circuit 10.
In the operation process of the current sampling circuit 220, the current sampling circuit 220 continuously sends a plurality of sampling signals to the control device 210 according to the above flow, the control device 210 can generate a current waveform according to the plurality of sampling signals, and then the control device 210 can calculate a current effective value according to the current waveform.
Note that, the noise signal is present in the signal transmitted to the amplifying unit 224 by the sampling unit 223, and the phase of the sampling signal may be changed by the noise signal, which may cause a difference between the phase of the current signal received by the control device 210 and the phase of the original current signal in the current-carrying circuit 10, which affects the subsequent operation. Therefore, in the present embodiment, the capacitor C1 and the capacitor C3 are disposed in the inverse proportional amplifier, so as to filter out the noise signal in the sampling signal, and fully ensure the orderly proceeding of the subsequent operation.
Fig. 4 is a flowchart illustrating a control method of the circuit breaker 20 according to an embodiment of the disclosure. The control method of the circuit breaker 20 includes the following steps S210 to S230.
Step S210: the current effective value of the current-carrying circuit 10 is calculated, and it is judged whether the current effective value reaches the current threshold value.
Wherein the effective value of the current is the root mean square value of the current.
In this step, the control device 210 calculates the effective current value of the current-carrying circuit 10 in real time during the operation of the current-carrying circuit 10. The calculation method of the effective current value is the same as the calculation method in the prior art, and is not repeated here. After calculating the current effective value, the control device 210 may determine whether the current effective value reaches the current threshold value. If the judgment result shows that the current effective value does not reach the current threshold value, the control device 210 does not perform any operation, so that the current-carrying circuit 10 continues to operate. If the judgment result shows that the current effective value reaches the current threshold, the control device 210 executes step S220.
Step S220: and if the current effective value reaches the current threshold value, determining the execution time.
The execution time is the time when the control device 210 sends a trigger instruction to the driving device of the circuit breaker 20; wherein the trigger instruction is used to instruct the circuit breaker 20 to change from the closed state to the open state.
In this step, if the current effective value reaches the current threshold, it is indicated that the current in the current-carrying circuit 10 is too large and the current-carrying circuit 10 has a potential safety hazard, so in order to protect the current-carrying circuit 10, the control device 210 determines the execution time, that is, determines the time for sending the trigger command to the driving device of the circuit breaker 20 when it is detected that the current effective value of the current-carrying circuit 10 reaches the current threshold. After the control device 210 determines the time for transmitting the trigger command to the driving device of the circuit breaker 20, the control device 210 may perform step S230.
Step S230: when the execution time is reached, a trigger instruction is sent to the circuit breaker 20 to cause the circuit breaker 20 to open at the target time in response to the trigger instruction.
The difference value between the target time and the current period is within a preset range; the current period is the time corresponding to the current zero crossing in the current carrying circuit 10. The preset range may be, for example, 0-10ms.
In this step, when the execution time is reached, the control device 210 may send a trigger command to the driving device of the circuit breaker 20, so that the circuit breaker 20 changes from the closed state to the open state after receiving the trigger command. Further, after the circuit breaker 20 is turned into the off state, the current-carrying circuit 10 is disconnected and stops working, so that the current-carrying circuit 10 is protected to avoid potential safety hazards of the current-carrying circuit 10. Specifically, the driving device of the circuit breaker 20 is connected with the moving contact and the fixed contact; when the driving device of the circuit breaker 20 does not receive the trigger instruction, the moving contact is contacted with the fixed contact, and the current-carrying circuit 10 is in a connection state; when the driving device of the circuit breaker 20 receives the trigger command, the driving device drives the moving contact to separate from the fixed contact, and the current-carrying circuit 10 is disconnected.
It is noted that, in the above step S230, when the control device 210 sends a trigger instruction to the circuit breaker 20 at the execution time, the circuit breaker 20 is opened at the target time; the difference between the target time and the time corresponding to the current zero crossing point is within a first preset range, that is, the target time is the time corresponding to the current zero crossing point, or the target time is close to the time corresponding to the current zero crossing point and is located near the time corresponding to the current zero crossing point. As can be seen from this, in step S230, after the control device 210 sends a trigger command to the circuit breaker 20 at execution time, the circuit breaker 20 is opened at or near the current zero crossing.
When the circuit breaker 20 is opened at the zero crossing point of the current, the current in the current-carrying circuit 10 is 0, and no arc is generated between the moving contact and the fixed contact. When the circuit breaker 20 is opened near the zero crossing point of the current, there are two cases, in which the circuit breaker 20 is opened before the zero crossing point of the current arrives, and weak arc is generated between the moving contact and the fixed contact in this case, but when the time reaches the time corresponding to the zero crossing point of the current, the current in the current-carrying circuit 10 is 0, and the weak arc generated between the moving contact and the fixed contact is extinguished quickly. In another case, the breaker 20 is opened after the zero crossing point of the current, and in this case, only weak electric arcs are generated between the moving contact and the fixed contact, the existence of the electric arcs does not affect the operation of the breaker 20, and the breaker 20 can still complete normal cutting operation, so that the current-carrying circuit 10 is disconnected; when the current-carrying circuit 10 is disconnected, an arc generated between the moving contact and the stationary contact is extinguished. It is thus seen that the present application is effective in performing an arc extinguishing operation on the circuit breaker 20 by opening the circuit breaker 20 at the zero crossing point of the current, or opening the circuit breaker 20 in the vicinity of the zero crossing point of the current. Through carrying out the arc extinguishing operation to circuit breaker 20, fully guaranteed when the electric current is too big in current-carrying circuit 10, circuit breaker 20 can normally work, ensure that current-carrying circuit 10 can be cut off completely, fully guaranteed current-carrying circuit 10's safety in utilization, avoid appearing the potential safety hazard. Meanwhile, through carrying out arc extinguishing operation on the circuit breaker 20, the moving contact and the fixed contact are prevented from being damaged by the arc, so that the moving contact and the fixed contact are worn, the service time of the circuit breaker 20 is greatly prolonged, and the service life of the circuit breaker 20 is prolonged.
Therefore, in the application, when a circuit in the current-carrying circuit is overloaded, the circuit breaker is disconnected near a current zero crossing point or a current zero crossing point in a hardware sampling and software control mode, the generation intensity of an electric arc is reduced in the mode, normal cutting-off work of the circuit breaker is ensured, and the use safety of the current-carrying circuit is ensured. Meanwhile, the abrasion of the electric arc to the fixed contact and the fixed contact can be effectively reduced by reducing the generation intensity of the electric arc, and the service life of the circuit breaker is greatly prolonged.
In an embodiment, before performing the step S210, the control device 210 calculates the effective current value of the current-carrying circuit 10, the following steps are further performed: the current sampling circuit 220 receives the sampling signal of the current-carrying circuit 10, and generates a current waveform from the sampling signal.
In this embodiment, when the current-carrying circuit 10 is operated, the current sampling circuit 220 continuously sends a plurality of sampling signals of the current-carrying circuit 10 to the control device 210; the transmission principle of the sampling signal is detailed in the description of the above embodiments, and is not repeated here; the sampling signal is a sampling point corresponding to the magnitude of the current at a certain moment. After receiving the sampling signals, the control device 210 records the magnitude of the current at each moment in each sampling signal, and then draws a partial current waveform according to the position relation of each sampling signal. Because the current waveform changes periodically, after drawing a part of the current waveform, the control device 210 can estimate the subsequent current waveform as long as knowing the current waveform in one period from the drawn part of the current waveform according to the characteristic of the periodic change of the current, and in this way, the control device 210 can draw a complete current waveform.
In one embodiment, the control device 210 may calculate the effective current value of the current-carrying circuit 10 according to the following steps: the current effective value is calculated from the current waveform.
In this step, since the current waveform includes the current amplitude information, the control device 210 can calculate the current effective value according to the current amplitude information in the current waveform after drawing the current waveform. The current waveform drawn according to the sampling signal can reflect the trend of the current in the current-carrying circuit 10, so the effective value of the current calculated according to the current waveform can reflect the effective value of the current in the current-carrying circuit 10.
In one embodiment, when the control device 210 detects that the current effective value reaches the current threshold value, the execution time may be determined by performing the following steps: the time is performed according to the current waveform.
In this step, when detecting that the current effective value of the current-carrying circuit 10 reaches the current threshold, the control device 210 may determine the execution time, that is, the time of sending the trigger command to the driving device of the circuit breaker 20, according to the current waveform drawn as described above.
The operation principle of the control device 210 in determining the execution time from the current waveform is explained in detail as follows:
(1) The current period is extracted from the current waveform. The current period is the time corresponding to the current zero crossing point in the current waveform.
In this step, when determining the execution time, the control device 210 may first extract the time corresponding to the current zero-crossing point from the current waveform.
It should be noted that, according to the description of the above embodiment, since the phase of the sampling current signal at each time in the current waveform is the same as the phase of the original current signal in the current-carrying circuit 10, the current waveform in this case can reflect the actual trend of the current in the current-carrying circuit 10, and the time of the current zero-crossing point extracted based on the current waveform must be accurate on this basis.
(2) And determining the execution time according to the current period, the pre-stored delay time and the current time. The delay time is the time difference between when the control device 210 sends a trigger command to when the circuit breaker 20 is opened, and the current time is the time when the current effective value reaches the current threshold value.
In this step, after the time corresponding to the current zero crossing point is extracted, the characteristic time with the smallest time difference from the current period can be selected, that is, the time corresponding to the current zero crossing point with the smallest time difference from the current period is selected. After the characteristic time is determined, a time difference between the characteristic time and the current time, i.e., a first time difference, is also determined accordingly. For example, assuming a first time difference of 5ms, the control device 210 issues a trigger command 5ms from the current time, and the circuit breaker 20 ideally opens at the zero crossing point of the current right after receiving the trigger command. However, in a situation where there is a certain delay between the control device 210 sending the trigger command and the actual opening of the circuit breaker 20, when the control device 210 sends the trigger command at the time corresponding to the zero crossing point of the current, the circuit breaker 20 will not open at the time corresponding to the zero crossing point of the current, but there will be a situation where the opening is delayed, which causes that the circuit in the current carrying circuit 10 has reached a certain amplitude at the moment when the circuit breaker 20 is opened, and an arc will be generated between the moving contact and the fixed contact of the circuit breaker 20. Therefore, in this application, in order to avoid the occurrence of the arc, or to reduce the intensity of the arc to the greatest extent, the delay time is subtracted from the first time difference after the first time difference is determined, that is, a difference operation is performed between the first time difference and the delay time, and then the execution time of the trigger command sent by the control device 210 to the driving device of the circuit breaker 20 is determined according to the result of the difference operation. The delay time is the time difference from when the control device 210 sends a trigger command to when the circuit breaker 20 is opened. For example, assuming that the delay time is 2ms and the first time difference is 5ms, the execution time is 3ms, and the control device 210 delays for 3s to send a trigger instruction to the circuit breaker 20 based on the current time, so that the circuit breaker 20 can be opened exactly at the time corresponding to the current zero crossing point.
In an embodiment, after executing step S220 and determining the execution time, the control device 210 may further execute the following steps: judging whether the execution time meets a preset condition or not; if the execution time does not meet the preset condition, determining a change period of the current in the current-carrying circuit 10 according to the current waveform; the execution time is redetermined based on the period of variation.
Wherein the preset condition is whether the preset condition is more than 0.
In this embodiment, since the execution time is determined according to the difference between the first time difference and the delay time, if the delay time is smaller than the first time difference, the determined execution time is a positive value, and the execution time is the time when the final control device 210 sends the trigger command. However, when the delay time is greater than the first time difference, the determined execution time will be a negative value, in which case it is indicated that the breaker 20 cannot be opened at the current zero crossing point closest to the current time, and it is necessary to delay for half a period to open the breaker 20 at the next current zero crossing point. Thus, in the present embodiment, when the determined execution time is detected as a negative value, the execution time is re-determined to open the circuit breaker 20 at the next zero-crossing point of the current in this way.
Since the current waveform is periodically changed, the change period of the current is a constant value, and the number of current zero-crossing points in each current period is also determined, in this case, the interval time between two adjacent current zero-crossing points can be represented by the change period of the current. In this embodiment, the period of current change in the current-carrying circuit 10 can be determined first, and then the time interval between two adjacent current zero-crossings can be solved according to the period of current change. After the solution is successful, adding the solved time interval to the determined execution time, namely the redetermined execution time. After that, when the control device 210 sends a trigger command to the circuit breaker 20 again after reaching the redetermined execution time, the circuit breaker 20 may also be opened at the zero crossing point of the current.
In an embodiment, the control device 210 further performs the following steps before executing the step S220 to determine the execution time: and receiving delay time.
In this embodiment, since the control device 210 uses the delay time when determining the execution time, the delay time can be tested in advance, and the delay time obtained by the final test can be sent to the control device 210. Specifically, the delay time may be tested by an oscilloscope. When the circuit breaker 20 is in the closed state, the contact resistance between the moving contact and the fixed contact is very small, and the voltage at the two ends of the circuit breaker 20 is also low. However, when the circuit breaker 20 is in the off state, the voltage between the moving contact and the fixed contact starts to rise, and the first voltage rising edge generated by the moving contact and the fixed contact at the moment of separation can be captured on the oscilloscope. Because the trigger command sent by the control device 210 is a high level signal, the second voltage rising edge generated by the trigger command can be captured on the oscilloscope. And performing difference operation on the time corresponding to the first voltage rising edge and the second voltage rising edge, wherein the result of the difference operation is the delay time.
In another embodiment, when the delay time is actually tested, the electric personnel can perform multiple tests, and the average value of multiple test results is taken as the delay time.
The following takes fig. 5 as an example to explain in detail the working principle of the control method of the circuit breaker 20 in the present application:
as shown in fig. 5, the control device 210 draws a current waveform as shown in fig. 5 based on the sampling signal sent from the current sampling circuit 220. Wherein the abscissa of the current waveform is time. After drawing the current waveform, the control device 210 calculates the current effective value of the current-carrying circuit 10, and after calculation, the control device 210 determines the time when the control device 210 sends the trigger instruction to the driving device of the circuit breaker 20 based on the current time W when the current effective value reaches the current threshold value at the time W. Specifically, the control device 210 extracts a current period from the current waveform, that is, extracts the times T2, T3, T4, T5, and T6 corresponding to the current zero-crossing points. It should be noted that, although T1 is also the time corresponding to the current zero crossing point, since T1 belongs to the time that has elapsed historically with respect to the current time, the determined execution time should be a time that has not arrived yet with respect to the current time, and therefore, it is not necessary to extract the time corresponding to the current zero crossing point located before the current time. And after the time extraction is successful, screening out the characteristic time T2 with the smallest time difference with the current time from the current period, and performing difference operation on the characteristic time T2 and the current time W after the screening is successful, wherein the result of the difference operation is T2-W, and the result is the first time difference. After the first time difference is obtained, the delay time T3 is subtracted from the first time difference to obtain the execution time y=t2-W-T3.
Then, it is determined whether the execution time Y is greater than 0, and if the execution time Y is greater than 0, and the execution time Y is 4ms, the control device 210 delays 4ms to send a trigger command to the circuit breaker 20 based on the current time W. If the execution time is less than 0, the control device 210 re-determines the execution time. Specifically, as shown in fig. 5, the current change period in the current waveform is F, one current change period includes 3 current zero crossings, and the 3 current zero crossings divide the one current change period into 2 segments, based on this feature, it can be solved that the time interval between two adjacent current zero crossings is F/2, and at this time, the control device 210 redetermines the execution time k=y+f/2. For example, if the determined execution time Y is-4 ms and the current change half period is 10ms, the redetermined execution time K is 6ms. On this basis, the control device 210 delays 6ms in sending a trigger command to the circuit breaker 20 on the basis of the current time W.
It is noted that, even if the execution time is determined in the above manner, the circuit breaker 20 may not be able to be accurately opened at the current zero crossing T2, but may be opened in the vicinity of the current zero crossing, due to an error. But this error is very small and the circuit breaker 20 will open very close to the zero crossing point of the current. When the current is disconnected before the zero crossing point, the intensity of the electric arc generated between the movable contact and the fixed contact is smaller, and when the current reaches the zero crossing point, the electric arc is extinguished along with the time. When the circuit breaker is disconnected after the current zero crossing point, only an arc with smaller intensity is generated between the moving contact and the fixed contact, the existence of the arc does not influence the work of the circuit breaker 20, and the circuit breaker 20 can still complete normal disconnection work, so that the current-carrying circuit 10 is disconnected; when the current-carrying circuit 10 is disconnected, an arc generated between the moving contact and the stationary contact is extinguished. As can be seen from this, in the present application, even if there is an error influence such that the circuit breaker 20 is not opened at the current zero crossing point, but is opened in the vicinity of the current zero crossing point, the arc extinguishing effect can be achieved. Thus, it can be seen that the control method of the circuit breaker 20 in the present application is robust.
As can be seen from the description of the various embodiments of the present application described above, in this application, by means of a strict program logic, it is ensured that the circuit breaker 20 is able to open at or near the zero current crossing, in such a way that the circuit breaker 20 is subjected to an arc extinguishing operation.
Fig. 6 is a schematic structural diagram of a control device 210 according to a first embodiment of the present application. As shown in fig. 6, the control device 210 includes a judging module 211, a determining module 212, and a transmitting module 213; the judging module 211 is configured to calculate a current effective value of the current-carrying circuit 10, and judge whether the current effective value reaches a current threshold; the determining module 212 is configured to determine an execution time if the current effective value reaches the current threshold; the sending module 213 is configured to send a trigger instruction to the circuit breaker 20 when the execution time is reached, so that the circuit breaker 20 opens at a target time in response to the trigger instruction.
Fig. 7 is a schematic structural diagram of a control device 210 according to a second embodiment of the present disclosure. As shown in fig. 7, in this embodiment, the control device 210 further includes a receiving module 214, where the receiving module 214 is configured to receive the sampling signal of the current-carrying circuit 10 sent by the current sampling circuit 220, and generate a current waveform according to the sampling signal.
In one embodiment, the determining module 211 is further configured to calculate a current effective value according to the current waveform.
In one embodiment, the determination module 212 is further configured to determine the execution time based on the current waveform.
In one embodiment, the determining module 212 is further configured to extract a current period from the current waveform, and determine the execution time according to the current period, the pre-stored delay time, and the current time.
In one embodiment, the determining module 212 is further configured to screen the characteristic time from the current period and determine the execution time according to a difference between the first time difference and the delay time.
In one embodiment, the determining module 212 is further configured to receive the delay time.
The implementation process of the functions and roles of each module in the control device 210 is specifically described in the implementation process of the corresponding steps in the control method of the circuit breaker 20, and will not be described herein again.
In the several embodiments provided in the present application, the disclosed apparatus and method may be implemented in other manners. The apparatus embodiments described above are merely illustrative, for example, flow diagrams and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, the functional modules in the embodiments of the present application may be integrated together to form a single part, or each module may exist alone, or two or more modules may be integrated to form a single part.

Claims (10)

1. A control method of a circuit breaker, the control method of the circuit breaker comprising:
calculating a current effective value of a current carrying circuit, and judging whether the current effective value reaches a current threshold value or not;
if the current effective value reaches the current threshold value, determining execution time;
when the execution time is reached, sending a trigger instruction to a circuit breaker so that the circuit breaker is opened at a target time in response to the trigger instruction; wherein the difference value between the target time and the current period is within a preset range; the current period is the time corresponding to the current zero crossing point in the current carrying circuit; the circuit breaker is connected in the current-carrying circuit, which is disconnected when the circuit breaker is opened.
2. The method of controlling a circuit breaker according to claim 1, wherein prior to said calculating the current effective value of the current carrying circuit, the method further comprises:
receiving a sampling signal of the current-carrying circuit sent by a current sampling circuit, and generating a current waveform according to the sampling signal; the current sampling circuit is connected with the current carrying circuit;
the calculating the effective current value of the current carrying circuit comprises:
calculating the current effective value according to the current waveform;
the determining the execution time includes:
and determining the execution time according to the current waveform.
3. The method of controlling a circuit breaker according to claim 2, wherein the determining the execution time from the current waveform includes:
extracting the current period from the current waveform;
determining the execution time according to the current period, the pre-stored delay time and the current time;
the delay time is a time difference from the triggering instruction to the circuit breaker to be opened, and the current time is a time for determining that the current effective value reaches the current threshold value.
4. The method according to claim 3, wherein the determining the execution time according to the current period, the pre-stored delay time, and the current time comprises:
screening out characteristic time from the current period;
determining the execution time according to the difference value between the first time difference and the delay time; the time difference between the characteristic time and the current time is the smallest, and the first time difference is the time difference between the characteristic time and the current time.
5. The method of controlling a circuit breaker according to claim 2, wherein after the determining the execution time, the method further comprises:
judging whether the execution time meets a preset condition or not;
if the execution time does not meet the preset condition, determining a change period of current in the current-carrying circuit according to the current waveform;
and redefining the execution time according to the change period.
6. The control method of a circuit breaker according to claim 3, wherein before the execution time is determined according to the current period, a pre-stored delay time and a present time, the control method of a circuit breaker further comprises:
and receiving the delay time.
7. A control system for a circuit breaker, the control system comprising:
the circuit breaker is connected in the current-carrying circuit;
the control device is positioned inside the circuit breaker and is connected with the current-carrying circuit;
wherein the control device is configured to calculate a current effective value of the current-carrying circuit, and execute the control method of the circuit breaker according to any one of claims 1 to 6 according to a calculation result of the current effective value.
8. The control system of a circuit breaker of claim 7, further comprising:
the current sampling circuit is positioned in the circuit breaker, and the control device is connected with the current carrying circuit through the current sampling circuit;
the current sampling circuit is used for sending a sampling signal of the current carrying circuit to the control device, and the control device is used for generating a current waveform according to the sampling signal and calculating the current effective value according to the current waveform.
9. The control system of a circuit breaker of claim 8, wherein the current sampling circuit comprises:
the induction unit is connected with the current-carrying circuit and is used for inducing a current signal in the current-carrying circuit;
the rectification unit is connected with the induction unit and used for rectifying the current signal transmitted by the induction unit;
the sampling unit is connected with the rectifying unit and is used for sampling the current signal transmitted by the rectifying unit to generate a sampling signal;
the amplifying unit is connected with the sampling unit and the control device and is used for amplifying the sampling signal transmitted by the sampling unit and sending the amplified sampling signal to the control device.
10. The control system of a circuit breaker according to claim 7, wherein the control device comprises:
the judging module is used for calculating the current effective value of the current carrying circuit and judging whether the current effective value reaches a current threshold value or not;
the determining module is used for determining the execution time if the current effective value reaches the current threshold value;
and the sending module is used for sending a trigger instruction to the circuit breaker when the execution time is reached, so that the circuit breaker is opened at the target time in response to the trigger instruction.
CN202310510885.9A 2023-05-05 2023-05-05 Control method and control system of circuit breaker Pending CN116470467A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310510885.9A CN116470467A (en) 2023-05-05 2023-05-05 Control method and control system of circuit breaker

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310510885.9A CN116470467A (en) 2023-05-05 2023-05-05 Control method and control system of circuit breaker

Publications (1)

Publication Number Publication Date
CN116470467A true CN116470467A (en) 2023-07-21

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310510885.9A Pending CN116470467A (en) 2023-05-05 2023-05-05 Control method and control system of circuit breaker

Country Status (1)

Country Link
CN (1) CN116470467A (en)

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