Short-time delayed tripping control method for a circuit breaker and a circuit breaker

Abstract

The present invention discloses a control method for short-time delayed tripping of a circuit breaker, belonging to the technical field of low-voltage circuit breakers. The control method for short-time delayed tripping of the circuit breaker in the present invention detects and records the tripping execution time during each tripping process of the circuit breaker, and dynamically adjusts the delay time before the controller microprocessor sends a tripping instruction based on historical data, so that the short-time delay protection time of the circuit breaker can approach the set value as much as possible. The present invention also discloses a circuit breaker. Compared with the prior art, the present invention can dynamically adjust the short-time delayed tripping time of the circuit breaker according to the actual situation, improving the safety and reliability of the system.

Description

Technical Field

[0001] The invention belongs to the technical field of low-voltage circuit breakers, and in particular relates to a circuit breaker definite time delay opening control method. Background Art

[0002] Low-voltage circuit breakers usually have a short-circuit short-delay protection function, which is used to realize the cascade application of circuit breakers. In this application mode, the short-circuit short-delay protection time set by the upper circuit breaker is greater than the protection time set by the lower circuit breaker. When the lower circuit breaker detects a short-circuit fault and opens, the upper circuit breaker does not open because the duration of the short-circuit current does not reach the set protection time, thereby reducing the scope of power outage.

[0003] At present, the short-circuit short-delay protection time that can be set for low-voltage circuit breakers is 100ms, 200ms, 300ms and 400ms. The short-circuit short-delay protection time consists of two parts: one is the time for the circuit breaker controller to send the opening control signal after detecting the short-circuit current, which can also be called the short delay time before the microprocessor sends the opening command; the other is the time from the controller sending the opening signal to the opening actuator completing the opening operation, which can also be called the opening execution time. The short-circuit short-delay protection time of the circuit breaker is the sum of the short delay time before the microprocessor sends the opening command and the opening execution time.

[0004] The prior art controls the accuracy of the short-circuit short-delay protection time of the circuit breaker. It is necessary to count the opening execution time of a large number of opening execution units, summarize a typical value and solidify it in the controller. The short-delay time before the microprocessor sends the opening instruction is obtained by subtracting the typical value of the opening execution time from the actual short-circuit short-delay protection time. Since there are some differences in the opening execution time of different opening actuators, the typical value method cannot control the accuracy of the short-circuit short-delay protection time of the circuit breaker at a high level. At the same time, the opening actuator may experience aging, wear and other problems during long-term use, resulting in a longer opening execution time, thereby causing the short-circuit short-delay protection time of the circuit breaker to exceed the nominal action time accuracy. Therefore, the short-circuit short-delay protection time of the circuit breaker in the industry is set to 100-400ms, and the interval between adjacent gears is 100ms, so as to prevent the circuit breaker from tripping when the short-circuit short-delay protection time of the circuit breaker changes, and ensure the reliability of the circuit breaker cascade application. However, in cascade applications, the short-circuit short-delay protection time of the upper circuit breaker must be set at a higher level, such as 400ms. When a short-circuit fault occurs in the lower line of the circuit breaker, but the fault current does not reach the short-circuit instantaneous protection current point, the circuit breaker needs 400ms to open. The longer opening time will cause greater losses to the circuit breaker and the line. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a short-delay protection tripping control method for a circuit breaker. By tracking the actual value and change trend of the circuit breaker's tripping execution time, the short-delay time before the microprocessor sends a tripping instruction is dynamically adjusted, so that the short-circuit short-delay protection time of the circuit breaker always remains within the nominal accuracy range; on this basis, the time difference between the short-delay protection time gears can be shortened, the circuit breaker can support more layers of cascade applications, and the upper-level circuit breaker in the cascade application can set a shorter protection time, thereby improving the service life of the circuit breaker and the line.

[0006] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0007] A short-delay tripping control method for a circuit breaker, the circuit breaker includes a controller and a tripping actuator; the controller includes a microprocessor, a tripping drive unit, and a closing-opening state detection unit; when the circuit breaker trips, the microprocessor of the controller sends a tripping instruction to the tripping drive unit, and at the same time records the sending time point of the tripping instruction. The tripping drive unit outputs a drive voltage after receiving the tripping instruction to make the tripping actuator complete the tripping process. The closing-opening state detection unit detects the closing-opening state of the circuit breaker in real time and sends it to the microprocessor. The microprocessor records the time point when the circuit breaker changes from the closing state to the tripping state, and calculates the time difference between the two time points. This time difference is the tripping execution time of the circuit breaker's tripping actuator; the microprocessor calculates and records the tripping execution time of each tripping process. When the circuit breaker performs short-circuit short-delay protection, according to the historical record of the tripping execution time, the short-delay time before the microprocessor sends a tripping instruction in the current tripping process is dynamically adjusted.

[0008] Preferably, the dynamic adjustment of the short-delay time before the microprocessor sends a tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Subtract the mean / maximum value / last value of the recorded tripping execution times of the most recent several times from the required short-circuit short-delay protection time of the circuit breaker, and use the result as the short-delay time before the microprocessor sends a tripping instruction in the current tripping process.

[0009] Preferably, the dynamic adjustment of the short-delay time before the microprocessor sends a tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Predict the tripping execution time in the current tripping process according to the historical record of the tripping execution time, and subtract the predicted value of the tripping execution time in the current tripping process from the required short-circuit short-delay protection time of the circuit breaker, and use the result as the short-delay time before the microprocessor sends a tripping instruction in the current tripping process.

[0010] Preferably, before sending a trip instruction to the microprocessor during the current trip process based on the historical record of the trip execution time, the short delay time is dynamically adjusted as follows: the difference between the previous and the penultimate trip execution times is used as the delay correction value, and the short delay time of the microprocessor in the previous trip process minus the delay correction value is used to obtain the short delay time of the microprocessor in the current trip process.

[0011] Further, the method further includes: after the controller microprocessor completes the detection of the trip execution time during each trip process, it determines whether the detected trip execution time is within a preset reference range. If it exceeds the reference range, it determines that the circuit breaker is abnormal and issues an alarm.

[0012] Furthermore, the upper limit of the reference range is less than or equal to the longest allowable trip time of the circuit breaker under the rated ultimate short-circuit current condition.

[0013] Preferably, the closing and tripping state detection unit includes a microswitch whose switch state is associated with the moving contact position of the trip actuator.

[0014] Based on the same inventive concept, the following technical solutions can also be obtained:

[0015] A circuit breaker, the circuit breaker includes a controller and a trip actuator; the controller includes a microprocessor, a trip drive unit, and a closing and tripping state detection unit; when the circuit breaker trips, the microprocessor of the controller sends a trip instruction to the trip drive unit, and at the same time records the sending time point of the trip instruction. After receiving the trip instruction, the trip drive unit outputs a drive voltage to make the trip actuator complete the trip process. The closing and tripping state detection unit real-time detects the closing and tripping state of the circuit breaker and sends it to the microprocessor. The microprocessor records the time point when the circuit breaker changes from the closing state to the tripping state, and calculates the time difference between the two time points. This time difference is the trip execution time of the trip actuator of the circuit breaker; the microprocessor calculates and records the trip execution time of each trip process. When the circuit breaker performs short-circuit short-delay protection, based on the historical record of the trip execution time, the short delay time before the microprocessor sends a trip instruction during the current trip process is dynamically adjusted;

[0016] A storage unit for recording the trip execution time;

[0017] A delay adjustment unit for dynamically adjusting the short delay time during the current trip process according to the historical record of the trip execution time.

[0018] Preferably, before sending a tripping instruction to the microprocessor during the current tripping process based on the historical record of the tripping execution time, the short delay time is dynamically adjusted as follows: Subtract the mean / maximum value / last value of the recorded tripping execution times of several recent times from the required short-circuit short-delay protection time of the circuit breaker, and use the result as the short delay time before the microprocessor sends a tripping instruction during the current tripping process.

[0019] Preferably, before sending a tripping instruction to the microprocessor during the current tripping process based on the historical record of the tripping execution time, the short delay time is dynamically adjusted as follows: Predict the tripping execution time during the current tripping process based on the historical record of the tripping execution time, and subtract the predicted value of the tripping execution time during the current tripping process from the required short-circuit short-delay protection time of the circuit breaker, and use the result as the short delay time before the microprocessor sends a tripping instruction during the current tripping process.

[0020] Preferably, before sending a tripping instruction to the microprocessor during the current tripping process based on the historical record of the tripping execution time, the short delay time is dynamically adjusted as follows: Use the difference between the last and the penultimate tripping execution times as the delay correction value, and subtract the delay correction value from the short delay time of the microprocessor during the last tripping process to obtain the short delay time of the microprocessor during the current tripping process.

[0021] Furthermore, the controller further includes:

[0022] An early warning unit, which is configured to, after detecting the tripping execution time during each tripping process, determine whether the detected tripping execution time is within a preset reference range. If it exceeds the reference range, it is determined that the circuit breaker is abnormal and an alarm is issued.

[0023] Furthermore, the upper limit of the reference range is less than or equal to the longest tripping time that the circuit breaker is allowed under the rated ultimate short-circuit current condition.

[0024] Preferably, the closing and tripping state detection unit includes a microswitch whose switch state is associated with the moving contact position of the tripping actuator.

[0025] Furthermore, the controller further includes an energy storage unit, which is configured to provide a short-term power supply for the controller when the controller loses external power supply.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] The present invention dynamically adjusts the time for delaying the sending of the controller's opening command according to the historical records of the opening execution time of the actuator, so that the overall opening time of the circuit breaker can be close to the set value, so that in the cascade application of the circuit breaker, the over-tripping situation will not occur;

[0028] The present invention can further generate an alarm for abnormal conditions of the opening actuator according to the opening execution time, such as aging of the actuator resulting in too long opening time and failure to meet application requirements, to remind the user to perform maintenance or replace the circuit breaker, thereby further improving the safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a specific embodiment of the circuit breaker of the present invention;

[0030] Figure 2 A schematic diagram of a specific method for dynamically adjusting the delay time;

[0031] Figure 3 A schematic diagram showing the principle of another specific method for dynamically adjusting the delay time. DETAILED DESCRIPTION

[0032] In view of the shortcomings of the prior art, the solution of the present invention is to detect and record the opening execution time of the circuit breaker during each opening process, and dynamically adjust the delay time before the controller microprocessor sends the opening command based on historical data, so that the short delay protection time of the circuit breaker can be as close to the set value as possible.

[0033] The technical solution proposed by the present invention is as follows:

[0034] A short-delay opening control method for a circuit breaker, the circuit breaker comprises a controller and an opening actuator; the controller comprises a microprocessor, an opening drive unit, and a closing and opening state detection unit; when the circuit breaker is opening, the microprocessor of the controller sends an opening instruction to the opening drive unit, and records the sending time point of the opening instruction at the same time; the opening drive unit outputs a driving voltage after receiving the opening instruction, so that the opening actuator completes the opening process; the closing and opening state detection unit detects the closing and opening states of the circuit breaker in real time and sends them to the microprocessor; the microprocessor records the time point when the circuit breaker changes from the closing state to the opening state, and calculates the time difference between the two time points, which is the opening execution time of the circuit breaker opening actuator; the microprocessor calculates and records the opening execution time of each opening process, and when the circuit breaker performs short-circuit short-delay protection, according to the historical record of the opening execution time, the short delay time before the microprocessor sends the opening instruction in the current opening process is dynamically adjusted.

[0035] In order to detect the opening operation time as continuously as possible, for any opening operation involving the controller, the detection and recording of the opening operation time will be carried out; the opening operations involving the controller include test opening, long-delay protection opening, short-delay protection opening, short-circuit instantaneous protection opening, ground protection opening, and other protection openings related to voltage, frequency, and power are also included.

[0036] When the circuit breaker performs a test opening or a protection opening, when the microprocessor of the controller sends an opening command to the opening drive unit, it records the sending time point of the opening command. After receiving the opening command, the opening drive unit converts the low-voltage and small-current controller signal into a drive signal with a higher voltage and a larger current and outputs it, so that the opening actuator completes the opening process. The opening mechanism mainly includes a flux converter, circuit breaker contacts and associated mechanical components. The flux converter realizes the conversion from electricity to force, thereby pushing the mechanical components to change the position of the circuit breaker contacts. The circuit breaker opening and closing state detection unit is associated with the position of the contacts and converts the opening and closing state of the circuit breaker into a high and low level form and sends it to the microprocessor. The microprocessor judges the current opening and closing state of the circuit breaker in real time according to the signal provided by the opening and closing detection unit. When the closing state changes to the opening state, the microprocessor records the current time point. The time difference obtained by subtracting the sending time point of the opening command from this time point is the opening operation time of the circuit breaker opening actuator.

[0037] The microprocessor calculates and records the opening operation time of each opening process. When the circuit breaker performs short-circuit short-delay protection, according to the historical record of the opening operation time, it dynamically adjusts the short-delay time before the microprocessor sends the opening command during the current opening process.

[0038] A circuit breaker, the circuit breaker includes a controller and an opening actuator; the controller includes a microprocessor, an opening drive unit, and an opening and closing state detection unit; when the circuit breaker opens, the microprocessor of the controller sends an opening command to the opening drive unit, and at the same time records the sending time point of the opening command. After receiving the opening command, the opening drive unit outputs a drive voltage to make the opening actuator complete the opening process. The opening and closing state detection unit detects the opening and closing state of the circuit breaker in real time and sends it to the microprocessor. The microprocessor records the time point when the circuit breaker changes from the closing state to the opening state and calculates the time difference between the two time points. This time difference is the opening operation time of the circuit breaker opening actuator; the microprocessor calculates and records the opening operation time of each opening process. When the circuit breaker performs short-circuit short-delay protection, according to the historical record of the opening operation time, it dynamically adjusts the short-delay time before the microprocessor sends the opening command during the current opening process;

[0039] A storage unit for recording the opening operation time;

[0040] A delay adjustment unit for dynamically adjusting the short delay time during the current opening process according to the historical record of the opening execution time.

[0041] In order to detect the opening execution time as continuously as possible, for any opening operation participated by the controller, the detection and recording of the opening execution time will be carried out; the opening operations participated by the controller include test opening, long-delay protection opening, short-delay protection opening, short-circuit instantaneous protection opening, ground protection opening, and other protection openings related to voltage, frequency, and power are also included.

[0042] When the circuit breaker performs a test opening or a protection opening, when the microprocessor of the controller sends an opening command to the opening drive unit, the sending time point of the opening command is recorded. After receiving the opening command, the opening drive unit converts the low-voltage and small-current controller signal into a drive signal with a higher voltage and a larger current for output, so that the opening actuator completes the opening process. The opening mechanism mainly includes a flux converter, a circuit breaker contact and associated mechanical components. The flux converter realizes the conversion from electricity to force, thereby pushing the mechanical components to change the position of the circuit breaker contact. The circuit breaker closing / opening state detection unit is associated with the position of the contact, and converts the closing / opening state of the circuit breaker into a high / low level form and sends it to the microprocessor. The microprocessor judges the current closing / opening state of the circuit breaker in real time according to the signal provided by the closing / opening detection unit. When the closing state changes to the opening state, the microprocessor records the current time point. The time difference obtained by subtracting the sending time point of the opening command from this time point is the opening execution time of the circuit breaker opening actuator.

[0043] The microprocessor calculates and records the opening execution time of each opening process. When the circuit breaker performs short-circuit short-delay protection, according to the historical record of the opening execution time, the short delay time before the microprocessor sends the opening command during the current opening process is dynamically adjusted;

[0044] A storage unit for recording the opening execution time;

[0045] A delay adjustment unit for dynamically adjusting the short delay time during the current opening process according to the historical record of the opening execution time.

[0046] The dynamic adjustment of the short delay time before the microprocessor sends the opening command according to the historical record of the opening execution time can adopt different implementation methods according to the actual situation, such as the computing and storage capabilities of the controller.

[0047] For example, for a controller with poor computing and storage capabilities, the average value of the opening execution times in the recent several opening processes can be directly used as the actual opening execution time of the circuit breaker in the current opening process, that is: subtracting the average value of the opening execution times in the recorded recent several opening processes from the required short-circuit short-time delay protection time, and using the obtained difference as the short-time delay before the microprocessor sends the opening instruction in the current opening process; it is also possible to use the maximum opening execution time in the recent several opening processes as the actual opening execution time of the circuit breaker in the current opening process, that is: subtracting the maximum value of the opening execution times in the recorded recent several opening processes from the required short-circuit short-time delay protection time, and using it as the short-time delay before the microprocessor sends the opening instruction in the current opening process; it is also possible to use the opening execution time of the most recent opening process as the actual opening execution time of the circuit breaker in the current opening process, that is: subtracting the opening execution time value in the recorded most recent opening process from the required short-circuit short-time delay protection time, and using it as the short-time delay before the microprocessor sends the opening instruction in the current opening process.

[0048] For a controller with strong computing and storage capabilities, the opening execution time in the current opening process can be accurately predicted according to the time series formed by the historical records of the opening execution times over a long period, using existing time series prediction methods such as linear regression and periodic factor method, as follows: predicting the opening execution time in the current opening process based on the historical records of the opening execution times, and subtracting the predicted value of the opening execution time in the current opening process from the required short-circuit short-time delay protection time, and using it as the short-time delay before the microprocessor sends the opening instruction in the current opening process.

[0049] Considering that there is a close connection between the opening execution time and the operating state of the opening actuator, the present invention further proposes to monitor the operating state of the opening actuator according to the detection result of the opening execution time, specifically: after the controller completes the detection of the opening execution time in each opening process, it judges whether the detected opening execution time is within the preset reference range. If it exceeds the reference range, it is determined that the circuit breaker is abnormal and an alarm is issued. As one of the preferred solutions, the upper limit of the reference range is less than or equal to the longest opening time allowed for the circuit breaker under the rated ultimate short-circuit current condition.

[0050] The detection of the opening and closing states of the circuit breaker is an existing mature technology. Currently, a microswitch is used more often. By setting the switch state of the microswitch to be associated with the position of the moving contact of the opening actuator, the opening and closing states of the circuit breaker can be detected through the change of the switch state of the microswitch.

[0051] For the convenience of the public to understand, the technical solution of the present invention will be described in detail below through a specific embodiment in conjunction with the drawings:

[0052] The circuit breaker structure of this embodiment is as follows Figure 1 shown, including a controller and a tripping actuator. The circuit breaker includes a controller and a tripping actuator. The controller includes a microprocessor, a delay adjustment unit (implemented by software, Figure 1 not shown in the figure), a tripping drive unit, a closing / opening state detection unit, an energy storage unit, a storage unit, and an indication unit.

[0053] When the circuit breaker conducts a tripping test or the operating current and voltage reach the tripping protection threshold of the circuit breaker, when the microprocessor sends a tripping command to the tripping drive unit, timing starts. At this time, the moving and static contacts of the circuit breaker have not been physically separated, and the output signal of the closing / opening state detection unit is state 1; the tripping drive unit starts to work, energizing the flux coil of the flux converter, converting electrical energy into mechanical force to unlock the operating mechanism, and the operating mechanism can perform a tripping operation to separate the moving and static contacts of the circuit breaker; when the moving contact moves to the set position, the output signal of the closing / opening state detection unit changes to state 2, and the controller stops timing; the recorded start and end time difference Δt is the tripping execution time of this tripping process, and this time difference Δt is sent to the storage unit for storage. The delay adjustment unit can dynamically adjust the short delay time before the microprocessor sends a tripping command in the current tripping process according to the historical data of the time difference Δt stored in the storage unit.

[0054] In practical applications, the circuit breaker may not be connected to an external auxiliary power supply and is only powered by its own energy transformer. When the circuit breaker trips, the energy transformer will instantaneously stop power supply, and the controller relies only on the electricity stored in the capacitor to maintain the operation of the microprocessor until the tripping execution time Δt is stored. A high-performance microprocessor consumes more power and may not be able to effectively collect the tripping execution time. Therefore, the controller of this embodiment also includes an energy storage unit, which provides short-term power supply for the microprocessor, the memory unit, and the closing / opening state detection unit when the controller loses external power supply until the acquisition work is completed. The energy storage unit starts storing electrical energy only after the microprocessor is started. Compared with the method of directly increasing the capacitor, it can avoid the problem of degradation of performance indicators caused by the prolonged power-on time of the microprocessor.

[0055] The microprocessor in this embodiment is a general-purpose microprocessor; the storage unit is a general-purpose non-volatile memory, which can be saved in the power-off state and can be EEPROM, FLASH MEMORY, etc.; the indication unit is a general light-emitting diode, digital tube, liquid crystal display, etc.

[0056] As Figure 1As shown in the figure, the opening drive unit in this embodiment includes a resistor R1, a resistor R2, a MOS transistor V1, and a diode D1. R1 is a current-limiting resistor, one end of which is connected to the I / O port of the microprocessor, and the other end is connected to the G pole of the MOS transistor V1. The MOS transistor is a voltage-driven component, and R1 can reduce the drive power consumption. R2 is a bias resistor, one end of which is connected to the G pole of the MOS transistor, and the other end is grounded to ensure that the G pole of the MOS transistor always maintains a low level in the non-controlled state and prevent the MOS transistor from being mis-conducted. The MOS transistor has a fast response speed. D1 is a freewheeling diode. Since an external flux converter is generally used to achieve the conversion from electricity to force, there will be a reverse voltage when the coil is working, and D1 can ensure the safety of the system. When the microprocessor sends out a high-level signal of MCU-TRIP (i.e., the opening command), the MOS transistor V1 is turned on, and the power supply VDD flows back to the ground after passing through the external flux coil, and the flux coil is charged. At the same time when the microprocessor sends out the MCU-TRIP signal, a timer is started to count, and this moment is recorded as T1.

[0057] As Figure 1 shown, the opening / closing state detection unit in this embodiment includes a resistor R3, a resistor R4, and a microswitch SM1. The opening / closing actuator includes a flux converter and an operating mechanism. After the electromagnetic coil of the flux converter is energized, the flux converter unlocks the operating mechanism, and the operating mechanism separates the moving and static contacts of the circuit breaker. By using the microswitch SM1 (certain mechanical components in the circuit breaker will surely move, and here the microswitch SM1 can be associated with the moving contact. When the moving contact moves to the specified position, the state of the microswitch S1 changes), the state change of the mechanical components can be quickly detected. The resistor R3 is an upper bias resistor, one end of which is connected to the VCC power supply, and the other end is connected to one terminal of the microswitch SM1. The other terminal of the microswitch SM1 is connected to the I / O port of the microprocessor and is also connected to the ground through the lower bias resistor R4 to ensure that the level collected by the microprocessor is always low in the non-controlled state. The default state of the microswitch SM1 is open. When the circuit breaker opens and the moving contact moves to the set position, the microswitch SM1 becomes short-circuited. In the case where the resistance value of the resistor R3 is much lower than that of R4, OFF-STATUS switches from low level to high level. After the microprocessor recognizes this change, the timing is stopped, and this moment is recorded as T2. Then, the time difference Δt between these two time points T1 and T2 is calculated and sent to the storage unit for storage.

[0058] The energy storage unit in this embodiment includes a resistor R5, a triode V2, a capacitor C1, and a diode D2. The resistor R5 is a lower bias resistor, one end of which is connected to the base of the triode, and the other end is grounded, which is used to ensure that the base of the triode V2 is always at a low level in the non-controlled state, and the triode is cut off; the base of the triode V2 is also connected to the I / O port of the microprocessor; when the microprocessor starts and sends a high level MCR-CHARGE, the triode V2 conducts, and the system power supply VCC charges the energy storage capacitor C1. When the system loses power supply, C1 supplies energy to VCC through the diode D2, so as to ensure that the microprocessor has enough time to complete the acquisition and storage of the time difference Δt as described above.

[0059] When the circuit breaker needs to perform a short-circuit short-time delay protection opening operation, the microprocessor reads the historical data of the time difference Δt from the storage unit, calculates the delay sending time of the opening command. After the corresponding delay of the microprocessor, it sends the MCU-TRIP signal to the opening drive unit, and at the same time starts a new calculation of the time difference Δt.

[0060] The dynamic adjustment of the delay time can adopt different implementation methods according to actual situations, such as the computing and storage capabilities of the controller.

[0061] For example, for a controller with poor computing and storage capabilities, the opening execution time in the most recent opening process can be directly used as the estimated value of the opening execution time in the current opening process. As Figure 2 shown, assuming that the time difference Δt between T2 and T1 recorded in the most recent opening process is 10 ms, and the required short-circuit short-time delay protection time is 100 ms, then 100 ms - 10 ms = 90 ms can be used as the delay time between the moment T0 when the operating current reaches the opening threshold of the circuit breaker and the moment T1 when the opening command is issued.

[0062] Alternatively, the difference between the opening execution times of the previous opening process and the penultimate opening process is used as the delay correction value, and the delay time of the previous opening process is subtracted by the delay correction value to obtain the delay time in the current opening process. As Figure 3As shown, assuming that the time difference Δt between T1 and T2 recorded in the previous opening process is 10ms, and the time difference Δt between T1 and T2 recorded in the previous opening process is 12ms, it indicates that the opening execution time is prolonged due to aging and wear of the actuator. In order to make the required short-circuit short-delay protection time of 100ms remain stable, the Δt (12ms) of the previous opening process can be subtracted from the Δt (10ms) of the previous opening process to obtain a delay correction value of 2ms, and then the delay time 90ms of the previous opening process can be subtracted from the delay correction value 2ms to obtain the delay time of 88ms between the moment T0 when the operating current reaches the circuit breaker opening threshold and the moment T1 when the opening command is issued in the current opening process.

[0063] For controllers with strong computing and storage capabilities, the opening execution time in the current opening process can be accurately predicted based on the time series formed by the historical records of the opening execution time over a longer period of time, using existing time series prediction methods such as linear regression and periodic factor method, and the delay time can be adjusted based on the prediction results.

[0064] In the storage unit of the present embodiment, a time difference Δt reference value is also solidified, and the time difference Δt reference value is less than or equal to the longest opening time that can be allowed for the circuit breaker under the rated limit short-circuit current. When the time difference Δt detected by the microprocessor is greater than the reference value, it indicates that the circuit breaker has already experienced performance degradation, and the microprocessor can issue an alarm prompt through some peripheral connected devices, such as a display, a light-emitting diode, a buzzer, etc. For example, if the circuit breaker is required to complete the circuit breaker opening operation within 80ms under the rated limit short-circuit current, and the latest detected time difference Δt is 90ms, it can be considered that the performance of the circuit breaker has been degraded, and when the short-circuit current exceeds a certain value, there is a safety hazard in completing the opening task, and the microprocessor can issue an alarm prompt through some peripheral connected devices to remind the user to perform maintenance, repair or replacement of the circuit breaker.

[0065] After adopting the present invention, the accuracy of the short-circuit short-delay protection time of the circuit breaker can always be maintained within the initial accuracy range, and the setting time can be expanded on the basis of the original four levels, for example, the four levels of 100ms, 200ms, 300ms, and 400ms are changed to seven levels of 100ms, 150ms, 200ms, 250ms, 300ms, 350ms, and 400ms. When the circuit breaker is cascaded, assuming that the lowest level circuit breaker (first level) is set to instantaneous action, the second level circuit breaker is set from 100ms. Before adopting the technical solution of the present invention, the protection time of the fifth level circuit breaker can only be set to 400ms. After adopting the technical solution of the present invention, the protection time of the fifth level circuit breaker can be shortened to 250ms, which can effectively reduce the loss of the circuit breaker and the power line under the short-circuit current.

Claims

1. A short-time delayed opening control method for a circuit breaker, the circuit breaker comprising a controller and a tripping actuator; characterized in that: The controller includes a microprocessor, a tripping drive unit, and a closing / open status detection unit; when the circuit breaker trips, the microprocessor of the controller sends a tripping instruction to the tripping drive unit, and at the same time records the time point when the tripping instruction is sent. After receiving the tripping instruction, the tripping drive unit outputs a drive voltage to cause the tripping actuator to complete the tripping process. The closing / open status detection unit detects the closing / open status of the circuit breaker in real time and sends it to the microprocessor. The microprocessor records the time point when the circuit breaker changes from the closed state to the open state, and calculates the time difference between the two time points. This time difference is the tripping execution time of the tripping actuator of the circuit breaker; the microprocessor calculates and records the tripping execution time of each tripping process. When the circuit breaker performs short-circuit short-time delay protection, according to the historical record of the tripping execution time, the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process is dynamically adjusted.

2. The circuit breaker short-time delayed opening control method according to claim 1, wherein, The dynamic adjustment of the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Subtract the mean value or the maximum value or the most recent value of the recorded tripping execution times of several recent times from the required short-circuit short-time delay protection time of the circuit breaker, and use the result as the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process.

3. The circuit breaker short-time delayed opening control method according to claim 1, characterized in that, The dynamic adjustment of the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Predict the tripping execution time in the current tripping process according to the historical record of the tripping execution time, and subtract the predicted value of the tripping execution time in the current tripping process from the required short-circuit short-time delay protection time of the circuit breaker, and use the result as the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process.

4. The circuit breaker short-time delayed opening control method according to claim 1, characterized in that, The dynamic adjustment of the short-time delay time before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Use the difference between the previous and the penultimate tripping execution times as the delay correction value, and subtract the delay correction value from the short-time delay time of the microprocessor in the previous tripping process to obtain the short-time delay time of the microprocessor in the current tripping process.

5. The circuit breaker short-time delayed opening control method according to claim 1, wherein, This method further includes: After the microprocessor of the controller completes the detection of the tripping execution time in each tripping process, it determines whether the detected tripping execution time is within a preset reference range. If it exceeds the reference range, it determines that the circuit breaker is abnormal and issues an alarm.

6. The circuit breaker short-time delayed opening control method according to claim 5, wherein, The upper limit of the reference range is less than or equal to the longest tripping time that the circuit breaker is allowed under the rated ultimate short-circuit current condition.

7. The circuit breaker short-time delayed opening control method according to claim 1, characterized in that, The closing / open status detection unit includes a microswitch whose switch status is associated with the moving contact position of the tripping actuator.

8. A circuit breaker, the circuit breaker comprising a controller and a tripping actuator; characterized in that: The controller includes a microprocessor, a tripping drive unit, and a closing and tripping state detection unit. When the circuit breaker trips, the microprocessor of the controller sends a tripping instruction to the tripping drive unit, and simultaneously records the time point when the tripping instruction is sent. After receiving the tripping instruction, the tripping drive unit outputs a driving voltage to cause the tripping actuator to complete the tripping process. The closing and tripping state detection unit detects the closing and tripping state of the circuit breaker in real time and sends it to the microprocessor. The microprocessor records the time point when the circuit breaker changes from the closed state to the tripped state, and calculates the time difference between the two time points. This time difference is the tripping execution time of the tripping actuator of the circuit breaker. The microprocessor calculates and records the tripping execution time of each tripping process. When the circuit breaker performs short-circuit short-time delay protection, according to the historical record of the tripping execution time, the short-time delay before the microprocessor sends the tripping instruction in the current tripping process is dynamically adjusted. A storage unit for recording the tripping execution time. A delay adjustment unit for dynamically adjusting the short-time delay in the current tripping process according to the historical record of the tripping execution time.

9. The circuit breaker according to claim 8, characterized in that, The dynamic adjustment of the short-time delay before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Subtract the mean value or maximum value or the value of the most recent several recorded tripping execution times from the required short-circuit short-time delay protection time of the circuit breaker, and use the result as the short-time delay before the microprocessor sends the tripping instruction in the current tripping process.

10. The circuit breaker according to claim 8, characterized in that, The dynamic adjustment of the short-time delay before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Predict the tripping execution time in the current tripping process according to the historical record of the tripping execution time, and subtract the predicted value of the tripping execution time in the current tripping process from the required short-circuit short-time delay protection time of the circuit breaker, and use the result as the short-time delay before the microprocessor sends the tripping instruction in the current tripping process.

11. The circuit breaker according to claim 8, wherein, The dynamic adjustment of the short-time delay before the microprocessor sends the tripping instruction in the current tripping process according to the historical record of the tripping execution time is as follows: Use the difference between the previous and the penultimate tripping execution times as the delay correction value, and subtract the delay correction value from the short-time delay of the microprocessor in the previous tripping process to obtain the short-time delay of the microprocessor in the current tripping process.

12. The circuit breaker according to claim 8, wherein, The controller further includes: An early warning unit for, after detecting the tripping execution time in each tripping process, determining whether the detected tripping execution time is within a preset reference range. If it exceeds the reference range, it is determined that the circuit breaker is abnormal and an alarm is issued.

13. The circuit breaker according to claim 12, wherein, The upper limit of the reference range is less than or equal to the longest tripping time that the circuit breaker is allowed under the rated ultimate short-circuit current condition.

14. The circuit breaker according to claim 8, wherein, The closing and tripping state detection unit includes a microswitch whose switch state is associated with the moving contact position of the tripping actuator.

15. The circuit breaker according to claim 8, characterized in that, The controller further includes an energy storage unit for providing a short-term power supply to the controller when the controller loses external power supply.

Images