Electric leakage self-checking method based on residual current protection circuit breaker

Abstract

The invention discloses an electric leakage self-checking method based on a residual current protection circuit breaker, and the method comprises the following steps: S1, obtaining a self-checking instruction through an MCU controller in the circuit breaker, and driving a simulation electric leakage circuit to generate a simulation electric leakage signal according to the self-checking instruction; s2, collecting a plurality of analog electric leakage signals in real time through a zero sequence mutual inductor in the circuit breaker, and processing the electric leakage signals to obtain a plurality of sampling voltages; and S3, preprocessing the plurality of sampling voltages to obtain an average sampling voltage, comparing the average sampling voltage with a preset voltage threshold to obtain a comparison result, controlling the running state of the release by the MCU controller according to the comparison result, recording a self-checking result, and outputting the self-checking result. The residual current protection circuit breaker is used for solving the problems that an existing residual current protection circuit breaker lacks a necessary electric leakage self-checking method, faults are prone to occurring in the using process, and the risks of electric leakage, short circuit and even human electric shock exist.

Description

Technical Field

[0001] This application relates to the technical field of leakage self-checking, and particularly to a leakage self-checking method based on a residual current protection circuit breaker. Background Art

[0002] In the scenario of temporary power use, due to reasons such as lax management, inadequate maintenance, and lack of professional management personnel, electrical equipment lacks regular maintenance and inspection, resulting in continued use after equipment aging and damage, increasing potential safety hazards, and there are risks of leakage, short circuit, and even electric shock to people. Residual current refers to the current that appears when the vector sum of the current input and output in a circuit is not zero. When insulation is damaged, or when a person or an object touches the circuit, the residual current will flow back from the ground. When the residual current is too large, it may cause an arc to generate, posing a fire hazard and causing electric shock injury to people. Therefore, from the perspective of protecting personal and property safety and achieving safe power use, a circuit breaker with residual current protection function is usually used in this kind of occasion to achieve the protection function.

[0003] However, the existing residual current protection circuit breakers lack necessary leakage self-checking methods, so they are prone to failures during use, and there are risks of leakage, short circuit, and even electric shock to people.

[0004] Therefore, in view of the problems existing in the above-mentioned prior art, a leakage self-checking method based on a residual current protection circuit breaker is proposed to solve them. Summary of the Invention

[0005] The embodiment of this application provides a leakage self-checking method based on a residual current protection circuit breaker to solve the technical problem that the existing residual current protection circuit breakers lack necessary leakage self-checking methods, so they are prone to failures during use, and there are risks of leakage, short circuit, and even electric shock to people.

[0006] In view of this, this application provides a leakage self-checking method based on a residual current protection circuit breaker, including the following steps:

[0007] S1. Obtain a self-checking instruction through the MCU controller in the circuit breaker, and drive an analog leakage circuit to generate an analog leakage signal according to the self-checking instruction;

[0008] S2. Real-time collect multiple analog leakage signals through the zero-sequence current transformer in the circuit breaker, and process the leakage signals to obtain multiple sampled voltages;

[0009] S3. Preprocess the multiple sampled voltages to obtain an average sampled voltage, compare the average sampled voltage with multiple preset voltage thresholds to obtain multiple comparison results, and the MCU controller controls the operating state of the trip unit according to the multiple comparison results and records the self-checking result.

[0010] Optionally, in step S3, the preprocessing of the multiple sampling voltages includes calculating the multiple sampling voltages through the FFT mean square error, and the calculation formula of the FFT mean square error is:

[0011] RMS = sqrt(∑xi ∧ 2 / n)

[0012] where xi represents each frequency component in the frequency domain, and n is the number of signal sampling points.

[0013] Optionally, determine whether the mutual inductor is damaged according to the comparison result in step S3;

[0014] If it is determined to be damaged, an alarm signal is sent and timing is started at the same time;

[0015] Control the operating state of the trip unit according to the timing result.

[0016] Optionally, 4. The leakage self-checking method based on a residual current protection circuit breaker according to claim 1, wherein in step S3, the average sampling voltage is compared with a preset voltage threshold to obtain a comparison result, and the method steps for the MCU controller to control the operating state of the trip unit are as follows:

[0017] The preset voltage threshold includes a first voltage threshold, a second voltage threshold, and a third voltage threshold, the first voltage threshold is greater than the second voltage threshold, and the second voltage threshold is greater than the third voltage threshold;

[0018] Update the comparison cumulative count value according to the comparison result;

[0019] If the comparison cumulative count value is not less than a preset value, control the trip circuit to perform a trip operation;

[0020] If the average sampling voltage is greater than the first voltage threshold, a first comparison result is obtained;

[0021] If the average sampling voltage is less than or equal to the first voltage threshold, and the average sampling voltage is greater than the second voltage threshold, a second comparison result is obtained;

[0022] If the average sampling voltage is less than the third voltage threshold, a third comparison result is obtained.

[0023] Optionally, before preprocessing the multiple sampling voltages to obtain the average sampling voltage, the method further includes: outputting the preprocessed sampling voltage through the conditioning circuit, collecting it to obtain the current sampling voltage, and correcting the parameter value of the current sampling voltage to the actual voltage parameter value;

[0024] Determine whether the number of acquisitions reaches the acquisition number threshold, where the number of acquisitions is the number of times of sampling the sampling voltage within one cycle;

[0025] Obtaining the average sampling voltage according to the preprocessed sampling voltage includes: if the number of acquisitions reaches the acquisition number threshold, calculating each sampling voltage within the current cycle to obtain the average sampling voltage.

[0026] Optionally, after correcting the parameter value of the current sampling voltage to the actual voltage parameter value, the method further includes: adding the parameter value of the current sampling voltage to the pre-stored voltage sum value to obtain the current voltage sum value, where the voltage sum value is the sum value of each sampling voltage collected before collecting the current sampling voltage within the current cycle;

[0027] Calculating each sampling voltage within the current cycle to obtain the average sampling voltage includes: calculating according to the number of acquisitions and the current voltage sum value to obtain the average sampling voltage.

[0028] Optionally, after correcting the parameter value of the current sampling voltage to the actual voltage parameter value, the method further includes: adding the parameter value of the current sampling voltage to the pre-stored voltage sum value to obtain the current voltage sum value, where the voltage sum value is the sum value of each sampling voltage collected before collecting the current sampling voltage within the current cycle;

[0029] Calculating each sampling voltage within the current cycle to obtain the average sampling voltage includes: calculating according to the number of acquisitions and the current voltage sum value to obtain the average sampling voltage. Before determining whether the number of acquisitions reaches the acquisition number threshold, the method further includes: determining whether the current sampling voltage is greater than the limit voltage threshold;

[0030] If the current sampling voltage is greater than the limit voltage threshold, accumulate the number of voltage overlimit times;

[0031] If the number of voltage overlimit times is greater than the pre-set voltage overlimit threshold, control the trip circuit to perform a trip operation.

[0032] Optionally, calculating each sampling voltage within the current cycle to obtain the average sampling voltage includes: obtaining the historical voltage sum value of the previous cycle;

[0033] Calculating according to the historical voltage sum value, the current voltage sum value and the number of acquisitions to obtain the average sampling voltage.

[0034] As can be seen from the above technical solutions, the embodiments of the present application have the following advantages:

[0035] The present application provides a leakage self-checking method based on a residual current protection circuit breaker. This method obtains a self-checking instruction through the MCU controller in the circuit breaker, and drives an analog leakage circuit to generate an analog leakage signal according to the self-checking instruction; then, multiple analog leakage signals are collected in real time through the zero-sequence current transformer in the circuit breaker, and the leakage signals are processed to obtain multiple sampling voltages, and the average sampling voltage is obtained by calculating the mean square error of the multiple sampling voltages through FFT; then, the average sampling voltage is compared with a preset voltage threshold to obtain a comparison result, and the MCU controller controls the operating state of the trip unit according to the comparison result and records it, realizing the leakage self-checking of the current protection circuit breaker, avoiding faults that are likely to occur during use, reducing the risks of leakage, short circuit, and even personal electric shock, and improving the degree of intelligence. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0037] Figure 1 It is a step diagram of the leakage self-checking method based on a residual current protection circuit breaker provided in the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0039] For ease of understanding, please refer to Figure 1 , the present invention provides a leakage self-checking method based on a residual current protection circuit breaker, including the following steps:

[0040] Including the following steps:

[0041] S1. Obtain a self-checking instruction through the MCU controller in the circuit breaker, and drive an analog leakage circuit to generate an analog leakage signal according to the self-checking instruction;

[0042] Specifically, there are two leakage self-checking operations. The first is to issue instructions through the gateway. The 485 module is used to communicate externally to collect the self-checking instructions of the gateway and transmit the instructions to the MCU controller. The second is to issue a self-checking instruction to the MCU controller through the button signal on the circuit breaker body.

[0043] S2. Real - time collect multiple analog leakage signals through the zero - sequence current transformer in the circuit breaker, and process the leakage signals, that is, convert the leakage current in the leakage signals into voltage output to obtain multiple sampled voltages.

[0044] S3. Pre - process the multiple sampled voltages to obtain the average sampled voltage, compare the average sampled voltage with multiple preset voltage thresholds to obtain multiple comparison results, and the MCU controller controls the operating state of the release according to the multiple comparison results and records the self - inspection results;

[0045] Specifically, pre - processing the multiple sampled voltages includes calculating the multiple sampled voltages through the FFT mean square error. The calculation formula of the FFT mean square error is:

[0046] RMS=sqrt(Σxi ∧ 2 / n)

[0047] Where xi represents each frequency component in the frequency domain, and n is the number of signal sampling points.

[0048] Furthermore, determine whether the current transformer is damaged according to the comparison result. That is, when the comparison result shows that the value of the average sampled voltage is greater than the preset voltage threshold, it is determined that the current transformer is damaged; if it is determined to be damaged, an alarm signal is sent to notify the on - site staff to carry out maintenance. At the same time, the time when the alarm signal is sent is timed. When no one has repaired and replaced the current transformer 12 hours after the alarm signal is sent, the release in the circuit breaker triggers tripping and locking, and manual or automatic reclosing is not allowed.

[0049] Furthermore, the method steps for comparing the average sampled voltage with the preset voltage threshold to obtain the comparison result and the MCU controller controlling the operating state of the release according to the comparison result are as follows:

[0050] The preset voltage thresholds include a first voltage threshold, a second voltage threshold, and a third voltage threshold. The first voltage threshold is greater than the second voltage threshold, and the second voltage threshold is greater than the third voltage threshold;

[0051] Update the comparison cumulative count value according to the comparison result;

[0052] If the comparison cumulative count value is not less than the preset value, control the tripping circuit to perform a tripping operation;

[0053] If the average sampled voltage is greater than the first voltage threshold, obtain the first comparison result;

[0054] If the average sampled voltage is less than or equal to the first voltage threshold and greater than the second voltage threshold, obtain the second comparison result;

[0055] If the average sampled voltage is less than the third voltage threshold, a third comparison result is obtained.

[0056] Further, after the MCU controller acquires the preprocessed sampled voltage, it can further process the preprocessed sampled voltage according to a preset algorithm, so as to determine whether to control the tripping circuit to perform a tripping operation according to the processing result.

[0057] Optionally, the MCU controller can determine whether the sampled voltage collected this time is the sampled voltage corresponding to the last collection point in the current sampling period. If it is the sampled voltage corresponding to the last collection point, it means that the current sampling period has been sampled. The average sampled voltage can be calculated based on the collected sampled voltages, and it is determined whether the average sampled voltage is greater than a preset voltage threshold, and the tripping circuit is controlled to perform a tripping operation according to the determination result.

[0058] It should be noted that it can be determined whether to control the tripping circuit to perform a tripping operation according to the number of times the average sampled voltage is greater than the preset voltage threshold and the amplitude of the average sampled voltage greater than the voltage threshold.

[0059] If the amplitude of the average sampled voltage greater than the voltage threshold is large and the number of times the average sampled voltage is greater than the preset voltage threshold is large, it means that the probability of the load circuit causing a safety accident is large, and it is necessary to quickly control the tripping circuit to perform a tripping operation.

[0060] Similarly, if the amplitude of the average sampled voltage greater than the voltage threshold is small and the number of times the average sampled voltage is greater than the preset voltage threshold is small, it means that the probability of the load circuit causing a safety accident is small, and detection can be continued. When the number of times the average sampled voltage is greater than the preset voltage threshold is large, the tripping circuit is then controlled to perform a tripping operation.

[0061] In summary, in the embodiment of the present application, the preprocessed sampled voltage sent by the conditioning circuit is received. The preprocessed sampled voltage is obtained by sampling the voltage signal converted from the residual current, and the tripping circuit is controlled to perform a tripping operation according to the preprocessed sampled voltage. The sampled voltage converted from the sampled residual current detected by the current transformer can be used to determine the magnitude of the residual current according to the sampled voltage. Therefore, it can be determined whether there is a residual current in the load circuit according to the sampled voltage, so as to control the tripping circuit to perform a tripping operation, avoiding the problem of detecting the residual current by using a complex circuit and improving the detection efficiency of the circuit breaker for leakage.

[0062] Further, before preprocessing a plurality of sampled voltages to obtain an average sampled voltage, the method further includes: outputting the preprocessed sampled voltage by the conditioning circuit, collecting it to obtain the current sampled voltage, and correcting the parameter value of the current sampled voltage to the actual voltage parameter value;

[0063] Specifically, since the MCU controller is connected to the output end of the conditioning circuit, the conditioning circuit can send the preprocessed sampled voltage to the MCU controller in real time. However, in actual applications, the MCU controller only needs to periodically collect the preprocessed sampled voltage. Moreover, within the sampling period, the MCU controller can collect multiple preprocessed sampled voltages according to multiple preset sampling points within the sampling period.

[0064] Optionally, during the process of collecting the sampled voltage corresponding to a certain sampling point, the MCU controller can collect the preprocessed sampled voltage output by the conditioning circuit to obtain the current sampled voltage, and correct the parameter value of the current sampled voltage to the actual voltage parameter value.

[0065] It should be noted that, for the convenience of calculating the average sampled voltage, after correcting the parameter value of the current sampled voltage to the actual voltage parameter value, the parameter value of the current sampled voltage can be added to the previously stored voltage sum value to obtain the current voltage sum value, where the voltage sum value is the sum value of the sampled voltages collected before collecting the current sampled voltage within the current period.

[0066] For example, if it is necessary to collect the preprocessed sampled voltages corresponding to 128 sampling points within the sampling period, and the current sampled voltage corresponds to the 120th sampling point, then the current sampled voltage can be added to the voltage sum value of the sampled voltages of the previous 119 sampling points to obtain the current voltage sum value including 120 sampled voltages.

[0067] In addition, since the voltage parameter value of the corrected current sampled voltage has positive and negative values, for the convenience of calculation, the corrected current sampled voltage can be squared and then added to the previously stored voltage sum value, so as to obtain the sum of squares of multiple sampled voltages.

[0068] Moreover, in order to determine the number of times of collecting the sampled voltage within the current period, the number of collections can be counted, and the number of collections is the number of times of collecting the sampled voltage within one period. Therefore, before correcting the current sampled voltage, the number of collections can be updated.

[0069] Further, after correcting the parameter value of the current sampled voltage to the actual voltage parameter value, the method further includes: adding the parameter value of the current sampled voltage to the previously stored voltage sum value to obtain the current voltage sum value, where the voltage sum value is the sum value of the sampled voltages collected before collecting the current sampled voltage within the current period;

[0070] Calculating the average sampling voltage for each sampling voltage in the current period includes: calculating the average sampling voltage based on the number of acquisitions and the sum of the current voltages. Before determining whether the number of acquisitions reaches the acquisition threshold, the method further includes: determining whether the current sampling voltage is greater than the limit voltage threshold;

[0071] If the current sampling voltage is greater than the limit voltage threshold, accumulate the number of voltage overrun times;

[0072] If the number of voltage overrun times is greater than the preset voltage overrun threshold, control the tripping circuit to perform a tripping operation.

[0073] Specifically, the step of determining whether the number of acquisitions reaches the acquisition threshold includes that after acquiring and correcting the current sampling voltage and updating the number of acquisitions, it can be determined whether the number of acquisitions corresponding to the current sampling voltage reaches the acquisition threshold. If the number of acquisitions does not reach the acquisition threshold, it indicates that the sampling voltage in the current sampling period has not been sampled completely.

[0074] However, if the acquisition threshold is reached, it means that the sampling voltages at all sampling points in the current sampling period have been acquired. Additionally, if the number of acquisitions has reached the acquisition threshold, the number of acquisitions can be initialized so that the parameter value corresponding to the number of acquisitions is replaced with the initial parameter value, so that in the next acquisition period, the number of times of sampling the sampling voltage can be statistically counted again.

[0075] For example, if the sampling period is 20 ms and there are 128 sampling points, and if the number of acquisitions is 127, comparing this number of acquisitions with the acquisition threshold of 128, it is determined that the number of acquisitions does not reach the acquisition threshold. Then the MCU controller can acquire the sampling voltage again after 20 / 128 = 0.156 ms, update the number of acquisitions to 128, and then compare the updated number of acquisitions with the acquisition threshold of 128. If it is determined that the number of acquisitions has reached the acquisition threshold, the number of acquisitions can be further initialized so that the number of acquisitions is reset to 0.

[0076] It should be noted that in order to avoid a sudden large change in the residual current in the load circuit, resulting in a safety accident, before determining whether the number of acquisitions reaches the acquisition threshold, it can be first determined whether the current sampling voltage is greater than the limit voltage threshold. If the current sampling voltage is greater than the limit voltage threshold, accumulate the number of voltage overrun times. If the number of voltage overrun times is greater than the preset voltage overrun threshold, control the tripping circuit to perform a tripping operation.

[0077] Among them, the voltage overlimit threshold is related to the limit voltage threshold. If the limit voltage threshold is higher, it indicates that the residual current is larger, and it is necessary to achieve open-circuit tripping in a short time to avoid safety accidents, so the voltage overlimit threshold is smaller. Correspondingly, if the limit voltage threshold is lower, it indicates that the residual current is smaller, and it is possible to detect the load circuit for a period of time before deciding whether to control the tripping circuit to perform a tripping operation, so the voltage overlimit threshold is larger.

[0078] The terms "first", "second", "third", "fourth", etc. (if any) in the description of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0079] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A leakage self-detection method based on a residual current protection circuit breaker, characterized in that: The following steps are involved: S1, obtaining a self-test instruction through the MCU controller in the circuit breaker, and driving the simulated leakage circuit to generate a simulated leakage signal according to the self-test instruction; S2. Collect multiple simulated leakage signals in real time through the zero-sequence mutual inductor in the circuit breaker, and process the leakage signals to obtain multiple sampled voltages; S3, preprocessing the multiple sampled voltages to obtain an average sampled voltage, comparing the average sampled voltage with multiple preset voltage thresholds to obtain multiple comparison results, the MCU controller controls the operating state of the release according to the multiple comparison results, and records the self-test results.

2. The leakage self-detection method based on residual current protection circuit breaker according to claim 1 is characterized in that: In the step S3, the preprocessing of the plurality of sampled voltages includes calculating the plurality of sampled voltages by means of FFT mean square error, and the calculation formula of the FFT mean square error is: RMS=sqrt(Σxi ∧ 2 / n) Among them, xi represents the frequency components in the frequency domain, and n is the number of sampling points of the signal.

3. The leakage self-detection method based on residual current protection circuit breaker according to claim 1 is characterized in that: Determine whether the mutual inductor is damaged according to the comparison result in step S3; If it is judged to be damaged, an alarm signal will be issued and timing will be started at the same time; The operating state of the release is controlled according to the timing result.

4. The leakage self-detection method based on residual current protection circuit breaker according to claim 1, characterized in that: In step S3, the average sampled voltage is compared with a preset voltage threshold to obtain a comparison result, and the method steps for the MCU controller to control the operating state of the release according to the comparison result are as follows: The preset voltage threshold includes a first voltage threshold, a second voltage threshold and a third voltage threshold, the first voltage threshold is greater than the second voltage threshold, and the second voltage threshold is greater than the third voltage threshold; According to the comparison result, updating the comparison cumulative count value; If the compared cumulative count value is not less than a pre-set value, controlling the tripping circuit to perform a tripping operation; If the average sampled voltage is greater than the first voltage threshold, a first comparison result is obtained; If the average sampled voltage is less than or equal to the first voltage threshold, and the average sampled voltage is greater than the second voltage threshold, a second comparison result is obtained; If the average sampled voltage is less than the third voltage threshold, a third comparison result is obtained.

5. The leakage self-detection method based on residual current protection circuit breaker according to claim 4, characterized in that: Before the preprocessing of the plurality of sampled voltages to obtain the average sampled voltage, the method further comprises: collecting the preprocessed sampled voltage output by the conditioning circuit to obtain the current sampled voltage, and correcting the parameter value of the current sampled voltage to the actual voltage parameter value; Determine whether the acquisition times reaches the acquisition times threshold, where the acquisition times is the number of times the sampled voltage is acquired in one cycle; The obtaining of the average sampled voltage according to the preprocessed sampled voltage includes: if the number of acquisitions reaches the acquisition number threshold, calculating each sampled voltage in the current cycle to obtain the average sampled voltage.

6. The leakage self-detection method based on residual current protection circuit breaker according to claim 5, characterized in that: After the parameter value of the current sampled voltage is corrected to the actual voltage parameter value, the method further includes: adding the parameter value of the current sampled voltage to a pre-stored voltage sum value to obtain a current voltage sum value, wherein the voltage sum value is a sum of the sampled voltages acquired in the current cycle before the current sampled voltage is acquired; The calculating each sampled voltage in the current cycle to obtain the average sampled voltage includes: calculating according to the number of acquisitions and the current voltage and value to obtain the average sampled voltage.

7. The method according to claim 5, characterized in that Before determining whether the acquisition times have reached the acquisition times threshold, the method further includes: determining whether the current sampling voltage is greater than the limit voltage threshold; If the current sampled voltage is greater than the limit voltage threshold, the number of voltage exceeding the limit is accumulated; If the voltage over-limit times is greater than a preset voltage over-limit threshold, the tripping circuit is controlled to perform a tripping operation.

8. The method according to claim 6, characterized in that The step of calculating each sampled voltage in the current cycle to obtain the average sampled voltage includes: obtaining a historical voltage and value of the previous cycle; The average sampled voltage is obtained by performing calculation according to the historical voltage and value, the current voltage and value and the number of acquisitions.

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