Circuit breaker selective protection method and circuit breaker

Abstract

The invention discloses a circuit breaker selective protection method. The method comprises the following steps: respectively establishing a communication link between a superior circuit breaker and a subordinate circuit breaker as well as a communication link between a master station system; reading protection action parameters and mechanical opening action time of the lower-stage circuit breaker, and configuring a protection early warning current value and a protection early warning delay value of the upper-stage circuit breaker according to the protection action parameters and the mechanical opening action time of the lower-stage circuit breaker; the upper-level circuit breaker detects line current and judges whether a fault occurs or not; if a fault occurs, the lower-level circuit breaker executes tripping protection; and the upper-level circuit breaker synchronously carries out protection early warning and judges whether the fault of the lower-level circuit breaker is eliminated after the delay time of the protection early warning delay value, and if the fault is not eliminated, opening protection of the upper-level circuit breaker is started. According to the invention, the technical problems of long fault time and large damage to equipment caused by the fact that instant tripping protection cannot be realized by the existing method are solved.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a circuit breaker selective protection method and a circuit breaker. Background Art

[0002] Selective protection refers to the coordination of the action characteristics of two or more protection devices. When a short circuit, grounding or other overcurrent occurs within a specified range, the device specified to act within this range will act to remove the fault, while the device outside this range will not act. That is, when an overcurrent fault occurs at a certain point in the low-voltage power distribution system, the electrical equipment of the power distribution will selectively open and close according to the pre-defined action sequence, and over-tripping is never allowed. The significance of selective protection is that when a short circuit fault, grounding or other overcurrent phenomenon occurs in the low-voltage power distribution system, the protection device in the distribution system must be able to reliably remove the fault and ensure that the power outage range is minimized. At present, the existing selective protection is mostly realized by setting the delay protection, that is, when the upper and lower levels are selectively coordinated, the upper circuit breaker adds a fixed delay time. When a fault occurs, the lower circuit breaker trips first. At this time, the fault is cleared, and the upper circuit breaker exits the protection; if the lower circuit breaker does not trip, the upper circuit breaker implements trip protection after a delay to avoid the expansion of the fault range, that is, the lower circuit breaker is configured as short-circuit instantaneous, and the upper circuit breaker is configured as short-circuit delay. In this way, since the delay time is generally pre-set, if the lower circuit breaker does not trip, then even if the short-circuit fault has occurred, the upper circuit breaker must be tripped after a fixed delay, thus causing the fault time to be extended and the damage to the equipment to be relatively large. Therefore, it is urgent to propose a circuit breaker selective protection method and circuit breaker to solve the technical problem that the existing method cannot achieve instant trip protection, resulting in a long fault time and greater damage to the equipment. Summary of the invention

[0003] The main purpose of the present invention is to propose a circuit breaker selective protection method and a circuit breaker, aiming to solve the technical problem that the existing method cannot achieve instant tripping protection, thus resulting in long fault time and greater damage to equipment.

[0004] To achieve the above object, the present invention provides a circuit breaker selective protection method, wherein the circuit breaker selective protection method comprises the following steps:

[0005] S1. Establish communication links between the upper circuit breaker, the lower circuit breaker and the master station system respectively;

[0006] S2, reading the protection action parameters and mechanical opening action time of the lower-level circuit breaker, and configuring the protection warning current value and protection warning delay value of the upper-level circuit breaker according to the protection action parameters and mechanical opening action time of the lower-level circuit breaker;

[0007] S3, the upper circuit breaker detects the line current and determines whether a fault occurs;

[0008] If a fault occurs, the lower-level circuit breaker will perform tripping protection; the upper-level circuit breaker will simultaneously perform protection warning, and determine whether the fault of the lower-level circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper-level circuit breaker will start the tripping protection.

[0009] In one of the preferred solutions, the protection action parameters include overload, short circuit short delay action current value, action delay time and short circuit instantaneous action current value.

[0010] In one of the preferred solutions, step S2 is specifically:

[0011] Read the protection action parameters and mechanical opening action time of the lower-level circuit breaker;

[0012] Configure the protection warning current value and protection warning delay value of the upper circuit breaker according to the protection action parameters and mechanical opening action time of the lower circuit breaker;

[0013] The master station system obtains the circuit impedance value from the power supply end to the output end of the lower circuit breaker, calculates the maximum fault short-circuit current of the circuit, and configures the protection warning over-limit current value based on the maximum fault short-circuit current.

[0014] In one of the preferred solutions, the protection warning delay value of the upper circuit breaker is greater than the sum of the protection action delay time of the lower circuit breaker and the mechanical opening action time of the lower circuit breaker.

[0015] In one of the preferred solutions, the upper level circuit breaker can be configured with multiple protection warning current values ​​and protection warning delay values.

[0016] One of the preferred solutions, in step S3, the upper circuit breaker detects the line current to determine whether a fault occurs, specifically:

[0017] The upper circuit breaker detects the line current in real time;

[0018] If the line current detected by the upper circuit breaker is greater than the protection warning current value, a fault occurs; otherwise, no fault occurs.

[0019] In one of the preferred solutions, the step S3 further includes: if the line current is greater than the protection warning over-limit current value, the upper level circuit breaker performs protection according to preset protection action parameters.

[0020] One of the preferred schemes, in step S3, the upper circuit breaker synchronously performs a protection warning, and determines whether the fault of the lower circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper circuit breaker opening protection is started. Specifically, the upper circuit breaker synchronously performs a protection warning, and when the upper circuit breaker execution action delay time reaches the lower circuit breaker to complete the mechanical opening action time, the line current is read for the second time. If the secondary current value is greater than the protection warning current value, it is determined that the short-circuit fault has not been eliminated and the lower circuit breaker has not achieved opening, then the upper circuit breaker opening protection action is started; if the secondary current value is less than the protection warning current value, it is determined that the short-circuit fault is eliminated, and the upper circuit breaker exits the protection.

[0021] A circuit breaker including the circuit breaker selective protection method, the circuit breaker including a communication module; the communication module is used to communicate with the upper circuit breaker and / or the lower circuit breaker and the master station system, and is used to receive protection action parameters sent by the master station system.

[0022] In one of the preferred solutions, the circuit breaker includes a memory, and the memory is used to store protection action parameters.

[0023] In the above technical solution of the present invention, the circuit breaker selective protection method includes the following steps: respectively establish a communication link between the upper circuit breaker and the lower circuit breaker and the master station system; read the protection action parameters and mechanical opening action time of the lower circuit breaker, and configure the protection warning current value and protection warning delay value of the upper circuit breaker according to the protection action parameters and mechanical opening action time of the lower circuit breaker; the upper circuit breaker detects the line current to determine whether a fault occurs; if a fault occurs, the lower circuit breaker performs tripping protection; the upper circuit breaker performs a protection warning synchronously, and determines whether the fault of the lower circuit breaker is eliminated after the delay time of the protection warning delay value, and if not eliminated, the upper circuit breaker is started for opening protection. In the present invention, when the lower circuit breaker does not have an opening action, the upper circuit breaker can realize tripping protection without executing a delay, thereby improving the protection time and solving the technical problem that the existing method cannot realize instant tripping protection, thereby causing a long fault time and greater damage to the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 A schematic diagram of a circuit breaker selective protection method according to an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the connection between the upper circuit breaker and the lower circuit breaker according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of parameter configuration of an upper circuit breaker and a lower circuit breaker according to an embodiment of the present invention.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0032] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] See also Figure 1-Figure 3 According to one aspect of the present invention, the present invention provides a circuit breaker selective protection method, wherein the circuit breaker selective protection method comprises the following steps:

[0034] S1. Establish communication links between the upper circuit breaker, the lower circuit breaker and the master station system respectively;

[0035] S2, reading the protection action parameters and mechanical opening action time of the lower-level circuit breaker, and configuring the protection warning current value and protection warning delay value of the upper-level circuit breaker according to the protection action parameters and mechanical opening action time of the lower-level circuit breaker;

[0036] S3, the upper circuit breaker detects the line current and determines whether a fault occurs;

[0037] If a fault occurs, the lower-level circuit breaker will perform tripping protection; the upper-level circuit breaker will simultaneously perform protection warning, and determine whether the fault of the lower-level circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper-level circuit breaker will start the tripping protection.

[0038] Specifically, in this embodiment, the protection action parameters include overload, short circuit short delay action current value, action delay time and short circuit instantaneous action current value.

[0039] Specifically, in this embodiment, the step S2 is specifically:

[0040] Read the protection action parameters and mechanical opening action time of the lower-level circuit breaker;

[0041] Configure the protection warning current value and protection warning delay value of the upper circuit breaker according to the protection action parameters and mechanical opening action time of the lower circuit breaker;

[0042] The master station system obtains the circuit impedance value from the power supply end to the outlet end of the lower circuit breaker, calculates the maximum fault short-circuit current of the circuit, and configures the protection warning over-limit current value based on the maximum fault short-circuit current. Specifically, in this embodiment, the protection warning delay value of the upper circuit breaker is greater than the sum of the protection action delay time of the lower circuit breaker and the mechanical opening action time of the lower circuit breaker.

[0043] Specifically, in this embodiment, the upper circuit breaker can be configured with multiple protection warning current values ​​and protection warning delay values. The protection warning parameters of the upper circuit breaker are for distribution lines of multiple lower circuit breakers. The upper circuit breaker can also be configured with multiple sets of protection warning parameters. The specific set of protection warning parameters to be used is determined by the matching between the detected fault current of the line and the warning parameters, that is, the fault current is determined according to the minimum protection warning parameter.

[0044] Specifically, in this embodiment, in step S3, the upper circuit breaker detects the line current and determines whether a fault occurs, specifically:

[0045] Both the upper and lower circuit breakers detect the line current in real time;

[0046] Determine whether the line current is greater than the protection warning current value; if so, a short circuit fault occurs at the outlet end of the lower-level circuit breaker. At this time, the lower-level circuit breaker performs a tripping protection action, and the lower-level circuit breaker contacts are completely opened after the mechanical opening action time, the circuit is disconnected, the fault is cleared, and the fault current disappears; otherwise, no fault occurs.

[0047] Specifically, in the present embodiment, in the step S3, the upper circuit breaker synchronously performs a protection warning, and determines whether the fault of the lower circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper circuit breaker opening protection is started. Specifically, if the line current detected by the upper circuit breaker is greater than the protection warning current value and less than the protection warning over-limit current value, the upper circuit breaker synchronously performs a protection warning and a protection action calculation. When the upper circuit breaker executes the action delay time and reaches the time for the lower circuit breaker to complete the mechanical opening action, the line current is read for the second time. If the secondary current value is greater than the protection warning current value, it is determined that the short-circuit fault has not been eliminated and the lower circuit breaker has not achieved opening, then the upper circuit breaker opening protection action is started; if the secondary current value is less than the protection warning current value, it is determined that the short-circuit fault is eliminated, and the upper circuit breaker exits the protection.

[0048] Specifically, in this embodiment, if the line current detected by the upper circuit breaker is greater than the protection warning over-limit current value, the upper circuit breaker performs protection according to the preset protection action parameters; the original protection action parameters of the upper circuit breaker are not affected, and are used to perform the fault protection function for the maximum range protected by this circuit breaker.

[0049] Specifically, in this embodiment, the upper circuit breaker and the lower circuit breaker can communicate with each other, and the protection action parameters of the upper circuit breaker and the lower circuit breaker can be issued by the master station to implement the configuration of the protection action parameters of the circuit breaker.

[0050] Specifically, in this embodiment, see Figure 3 ,use Figure 3The upper circuit breaker is configured with the protection warning parameters set to 250A according to the protection parameter of the lower circuit breaker, which is the warning current Iyj=2000A and the warning time Tyj=0.13s. When the lower circuit breaker fails, the fault current is 2200A, and the fault current does not reach the warning over-limit current value. Both the lower and upper circuit breakers detect the fault, and the lower circuit breaker starts the protection delay, and the upper circuit breaker starts the protection warning synchronously. When the fault lasts for 0.1s, the lower circuit breaker starts the protection tripping. After 0.03s, the lower circuit breaker opening mechanism is completed, the circuit is disconnected, and the fault is cleared. The corresponding upper circuit breaker, that is, at 0.13s, s, the fault current is eliminated, then the warning is exited; however, if after the fault occurs, when the lower-level circuit breaker does not perform protection, that is, after 0.13s, the upper-level circuit breaker detects that the fault current still exists, at this time the upper-level circuit breaker has exceeded the warning delay value, then the upper-level circuit breaker immediately performs tripping protection to clear the outgoing line side fault of the lower-level circuit breaker; if the circuit breaker does not have this warning function, since the fault current only reaches the short-circuit protection action threshold of the lower-level circuit breaker, but does not reach the short-circuit protection action threshold of the upper-level circuit breaker, the upper-level circuit breaker will not perform short-circuit protection, but will only perform the overload long-delay protection of the upper-level circuit breaker, and its action time will be very long, resulting in prolonged fault time and greater damage to the equipment.

[0051] According to one aspect of the present invention, the present invention provides a circuit breaker, wherein the circuit breaker includes a communication module; the communication module is used to communicate with the upper circuit breaker and / or the lower circuit breaker and the master station system, and is used to receive protection action parameters issued by the master station.

[0052] Specifically, in this embodiment, the circuit breaker includes a memory, and the memory is used to store protection action parameters.

[0053] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A circuit breaker selective protection method, It is characterized in that The following steps are involved: S1. Establish communication links between the upper circuit breaker, the lower circuit breaker and the master station system respectively; S2, read the protection action parameters and mechanical opening action time of the lower circuit breaker, and configure the protection warning current value and protection warning delay value of the upper circuit breaker according to the protection action parameters and mechanical opening action time of the lower circuit breaker; S3, the upper circuit breaker detects the line current and determines whether a fault occurs; If a fault occurs, the lower level circuit breaker will perform trip protection; The upper circuit breaker performs protection warning synchronously, and determines whether the fault of the lower circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper circuit breaker opening protection is started.

2. A circuit breaker selective protection method according to claim 1, It is characterized in that The protection action parameters include overload, short circuit short delay action current value, action delay time and short circuit instantaneous action current value.

3. A circuit breaker selective protection method according to any one of claims 1-2, It is characterized in that The step S2 is specifically: Read the protection action parameters and mechanical opening action time of the lower-level circuit breaker; Configure the protection warning current value and protection warning delay value of the upper circuit breaker according to the protection action parameters and mechanical opening action time of the lower circuit breaker; The master station system obtains the circuit impedance value from the power supply end to the output end of the lower circuit breaker, calculates the maximum fault short-circuit current of the circuit, and configures the protection warning over-limit current value based on the maximum fault short-circuit current.

4. A circuit breaker selective protection method according to claim 3, It is characterized in that The protection warning delay value of the upper circuit breaker is greater than the sum of the protection action delay time of the lower circuit breaker and the mechanical opening action time of the lower circuit breaker.

5. A circuit breaker selective protection method according to any one of claims 1-2, It is characterized in that The upper level circuit breaker can be configured with a plurality of protection warning current values ​​and protection warning delay values.

6. A circuit breaker selective protection method according to claim 3, It is characterized in that In step S3, the upper circuit breaker detects the line current and determines whether a fault occurs, specifically: The upper circuit breaker detects the line current in real time; If the line current detected by the upper circuit breaker is greater than the protection warning current value, a fault occurs; otherwise, no fault occurs.

7. A circuit breaker selective protection method according to claim 6, It is characterized in that The step S3 also includes: if the line current is greater than the protection warning over-limit current value, the upper level circuit breaker performs protection according to the preset protection action parameters.

8. A circuit breaker selective protection method according to claim 6, It is characterized in that In the step S3, the upper circuit breaker performs a protection warning synchronously, and determines whether the fault of the lower circuit breaker is eliminated after the delay time of the protection warning delay value. If not, the upper circuit breaker opening protection is started. Specifically, the upper circuit breaker performs a protection warning synchronously. When the upper circuit breaker execution action delay time reaches the lower circuit breaker completion mechanical opening action time, the line current is read for the second time. If the secondary current value is greater than the protection warning current value, it is determined that the short-circuit fault has not been eliminated and the lower circuit breaker has not achieved opening, then the upper circuit breaker opening protection action is started; if the secondary current value is less than the protection warning current value, it is determined that the short-circuit fault is eliminated, and the upper circuit breaker exits the protection.

9. A circuit breaker comprising a circuit breaker selective protection method according to any one of claims 1 to 8, It is characterized in that The circuit breaker comprises a communication module; the communication module is used to establish a communication connection with an upper level circuit breaker and / or a lower level circuit breaker and a master station system, and is used to receive protection action parameters sent by the master station system.

10. A circuit breaker according to claim 9, It is characterized in that The circuit breaker comprises a memory, and the memory is used to store protection action parameters.

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